THE "SCHLAMM," or mud, thrown down from the water of coal washing has hitherto been regarded as worthless, says The Engineering and Mining Journal, except that sometimes a portion of the coal particles it contained have been separated and made of value by a washing process; but Bergassessor Haarmann, of Friedrichsthal, has invented a new method for treating it dry and dividing it into two products, one of which, with low ash content, is distinguished by its granular nature, while the other contains a large proportion of ash and is of the fineness of flour. The former of these two products is, on account of its low ash content, useful for various purposes, and the latter constitutes a fuel quite ready for use in coal dust firing. The method is founded on the circumstances, hitherto lost sight of, that the incombustible constituents of the "schlamm" chiefly consist of clay which was formerly more or less dissolved in the wash water; and on the mud being dried and subjected to a suitable mechanical process, the clay falls into fine dust, while the coal particles, on the contrary, retain their granular nature. The method is carried out by drying the mud and a subsequent fine sifting, which effects a breaking up of the lumps that occur in the dried "schlamm," and a separation into the two products above named. The dust that falls through the sieve has a high ash content, being in the nature of flour, while what remains behind is granular and has a low ash content. It seems to us that this game is hardly worth the candle.

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ELECTRICAL NOTES.

ELECTRICITY AT the Paris Exposition.—Electricity will play a large part at the Paris Exposition of 1900, says the Revue Technique. No less than 15,000 h.p. will be used for lighting and 5,000 h.p. for furnishing electric power to the various parts of the grounds. As far as possible all the machinery exhibited will be shown at work and for this purpose electric conductors will be laid down to all points on the grounds. The boiler plant will be located at the end of the Champ de Mars, and will occupy two spaces of 130 X 390 feet each, one being devoted to French boilers and the other to those of foreign makers. This plant will be in itself a very interesting exhibit. It is proposed to provide a capacity for evaporating not less than 440,000 pounds of water per hour.

AN INTERESTING little plant in which the rise and fall of the tides is used as motive power for the generation of electricity is described in L'Electricien. Near Ploumanach, on the northern coast of France, where the tides have a daily range of 39 feet, a small fish pond separated from the sea by a dike is arranged with gates so that at high tide the water flows in and fills it, the gates closing automatically when the tide recedes. The machinery of an old grist mill is used to operate a small dynamo, which charges a storage battery and furnishes light for the fish industry there. Another wheel in the same mill works an ice making machine, the whole being under the charge of one man. It is stated that the total daily expense for generating about 2,000 horse power hours is only $2.

PEAT BOGS as generators of electrical power are suggested by Dr. Frank in Stahl und Eisen. He says that the great peat bogs of North Germany may be thus utilized, and figures that one acre of bog, averaging 10 feet in thickness, contains about 1,000 tons of dried peat, or 313,000 tons per square mile; and 430 square miles would be equivalent in heating power to the 80,000,000 to 85,000,000 tons of coal annually mined in Germany. The bogs of the Ems Valley alone cover 13,000 square miles; and Dr. Frank proposes the erection in that district of a 10,000 horse power electric station, which would yearly consume 200,000 tons of peat, or the product of 200 acres. He would use the electrical energy on the Dortmund and Emshaven Canal, and for the manufacture of calcium carbide.

THE SUCCESS attending an application of electric towing on the Burgundy Canal was such that two new applications of electricity to canal haulage and also for barge propulsion were made last year in the neighborhood of Dijon, on the same canal, under the superintendence of M. Gaillot, Ingenieur des Ponts et Chaussees. In the method of haulage, says The London Engineer, the receptor dynamo is mounted on a tricycle, to which the name of "electric horse" has been given, and which, running on the towing path, takes its current from an air line consisting of two wires, mounted five meters (nearly 17 feet) above the surface. This "horse," which weighs two tons, and is guided by a driver mounted upon it through the front wheel, proceeds on the towing path like a traction engine; and the boats are connected with it by a rope, with automatic disengaging gear, in case the force of the stream or a gust of wind should drive a boat backward. Speeds of from 1,990 to 4,240 meters (mean 3,319 yards) were obtained with the electric horse, towing from three to four boats, so that it is more suitable than the electric propeller for towage in rivers or very long reaches; but it requires a driver, while the propeller, with which speeds of from 2,150 to 4,240 meters (mean 3,406 yards) per hour were obtained, is worked by the bargee on board his boat. The towing path is not worn, and there is no occasion for a tow rope, which always causes difficulty when two boats cross one another. M. Maillet and M. Dufourny, Belgian Ingenieurs des Ponts et Chaussees, who watched the trials, conclude that a practical solution of the question depends upon the cost of producing the motive power; but they also consider that horse haulage on canals will soon be superseded by mechanical traction, based on the use of an automotive tricycle, working with petroleum or some other hydrocarbon, and capable of running on the tow path without requiring any fixed plant.

IT HAS long been known that feathers and hair are electrical bodies, but until recently we have had little information about their electrical properties or the conditions in which these properties are manifested. Most of these phenomena were first observed by Exner, and in the work of Dr. Schwarze are found collected a mass of facts that cannot fail to interest the physician and the biologist; besides, we find there a description of Exner's apparatus which was used by Schwarze in most of his experiments on electrical phenomena of this kind. By the side of gold leaf electroscopes we see a feather electroscope, which is fastened to its support by means of a silken thread. A feather waved through the air is positively electrified, while the air itself seems to be charged with negative electricity.... Two feathers rubbed together in the natural position are so electrified that their lower surface is negative and the upper positive.... These experiments and others still have been utilized to study the vital relations of animals and the biological signification of these phenomena. Most feathers stick together and remain so even after being dried; if they then are waved through the air, the barbs of the feather separate, owing to differences of electrification. No bird needs to attend to its plumage at the end of a long flight, for while the large feathers are positively electrified by friction against the air, the white down has become negative, and so there is attraction between it and the feathers. Another consequence of this production of electricity during flight is that during winds, even the most violent, the plumage does not become ruffled, but rests tightly against the bird's body, for in this case the wing feathers, which overlap, rub against each other and become electrified in contrary senses. If the bird flies toward the ground, flapping its wings, it compresses the air below them, and, supposing that the wing feathers can bend aside, the experiments of Exner show that by the friction the upper side of one feather and the lower side of that which is just above are electrified oppositely, the more powerfully as the rubbing is greater, which always causes them to resume the normal position.—L'Electricien.

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SELECTED FORMULAE.

REMOVAL OF INK FROM HECTOGRAPH.—It is recommended in Suedd. Ap. Ztg. to pour crude hydrochloric acid upon the hectograph, rub with a wad of cotton, then wash off by holding under cold running water and drying with a cloth. The hectograph may be used again immediately.

TO CLEAN WALL PAPER.—Four ounces of pumice stone in fine powder are thoroughly mixed with 1 quart of flour and the mass is kneaded with water enough to form a thick dough. This dough is formed into rolls about 2 inches in diameter and 6 or 8 inches long; each one is sewed up in a piece of cotton cloth and then boiled in water for from 40 to 50 minutes—long enough to render the dough firm. After cooling and allowing the rolls to stand for several hours, the outer portion is peeled off and they are then ready for use, the paper being rubbed with them as in the bread process.—Druggist's Circular.

INSULATING COMPOUND.—Prof. Fessenden recommends for armature work a compound made by boiling pure linseed oil at about 200 degrees with 1/2 per cent. of borate of manganese, the boiling being continued for several hours, or until the oil begins to thicken. An advantage of this borated oil is that it always retains a slight stickiness, and so gives a good joint when wrapped around wires, etc. Many substances so used are not sticky and let moisture in through the joints. Where a smooth surface is required, it is readily obtained by dusting on a little talc. It can also be given a coat of japan on the outside.—American Electrician.

HOW TO CLEAN DIATOMS.—As a general rule, we may say that every specimen of diatomaceous earth or rock needs a special treatment. The following, however, may serve as a basic treatment, from which such departure may be taken in each case as the nature of the specimen would indicate: Boil the material in hydrochloric acid, in a test tube, from two to five minutes. Let settle, pour off the hydrochloric acid, substitute nitric acid in its place, and boil again for two or three minutes. Pour into a beaker of water, stir a moment with a glass rod and let settle. After the material has fallen to the bottom, decant the liquid, and fill with fresh water. Repeat the operation until the water no longer shows an acid reaction. A portion of the deposit may now be examined, and if not clean, boil the deposit with tincture of soap and water in equal parts, decant, wash, first with water, then with stronger ammonia water, and finally, with distilled water. This usually leaves the frustules bright and sharp.—National Druggist.

RED INDELIBLE INK.—It is said that by proceeding according to the following formula, an intense purple red color may be produced on fabrics, which is indelible in the customary sense of the word.

No. 1. Sodium carbonate 3 drs. Gum arabic 3 " Water 12 "

No. 2. Platinic chloride 1 dr. Distilled water 2 oz.

No. 3. Stannous chloride 1 dr. Distilled water 4 "

Moisten the place to be written upon with No. 1 and rub a warm iron over it until dry; then write with No. 2, and, when dry, moisten with No. 3. An intense and beautiful purple-red color is produced in this way. The following simpler and less expensive method of obtaining an indelible red mark on linen has been proposed by Wegler: Dilute egg albumen with an equal weight of water, rapidly stir with a glass rod until it foams, and then filter through linen. Mix the filtrate with a sufficient quantity of finely levigated vermilion until a rather thick liquid is obtained. Write with a quill, or gold pen, and then touch the reverse side of the fabric with a hot iron, coagulating the albumen. It is claimed that marks so made are affected by neither soaps, acids nor alkalies. This ink, or rather paint, is said to keep moderately well in securely stoppered bottles, but we should not rely on it as a "stock" article. A white paint for marking dark colored articles might be made by substituting zinc white for the red pigment in the foregoing formula.—Druggist's Circular.

BROWN OR BLACK DISCOLORATION OF SILVERED MIRRORS.—Generally these spots are due to faulty manipulation, too great dilution of the silver solution, or touching the plates with the fingers after they have been cleaned. Sometimes, however, they are due to chemical defects in the glass itself. In these cases, as a general thing, the discolorations occur only after several days—a faultless mirror having been made at first, and the browning subsequently developing slowly. The writer was a student in the laboratory of Baron Liebig during the time that distinguished chemist was carrying out the series of experiments which resulted in devising a method of making silver mirrors commercially. One of the greatest troubles with which he had to contend was this browning—the cause for which was never fully cleared up by him. Some years ago, the writer, having in his possession two mirrors made by Liebig, and which had gradually become brown throughout, undertook an examination of the deposit (which had been thoroughly protected from extraneous influences by a strong film of varnish), and was surprised to find that it consisted of a layer of silver sulphide. Without going into detail, the source of the change was later found to lie within the glass itself. In making glass to be used for mirrors, a considerable portion of sodium sulphate is used, and in annealing, this is partly reduced to sodium sulphide, which effloresces on the surface of the glass. This efflorescence is, of course, removed on cleaning the glass before silvering; but it is found that, in many instances, on exposure of the mirror to the light for some time, a further efflorescence occurs, and it is this which produces the discoloration in cases such as we have cited. It has been suggested that the tendency to subsequent efflorescence may be corrected by boiling the plates, intended for silvering, for a couple of minutes, in a 10 per cent. solution of sodium carbonate or bicarbonate. We have no experience with the process, however.—National Druggist.

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WILD AND DOMESTIC SHEEP IN THE BERLIN ZOOLOGICAL GARDEN.

As a rule, domestic animals are accorded very little space in zoological gardens, but, although it is doubtless the first duty of these popular institutions to show visitors animals which live in a wild state in foreign lands, it is well, where there is sufficient space and adequate means, to extend the limits of the collection so as to include natives of our own woods and fields, thus enabling people of a great city who are unfamiliar with nature to form an idea of the changes wrought in animal life by the influence of man, for domestic animals are a great aid in the study of natural history. The accompanying engravings are reproductions of instantaneous photographs of occupants of the new sheep and goat house—mostly foreign breeds; but there are a few that belong to that South European-Asiatic group which are looked upon as the progenitors of the domestic sheep: the mouflon, of Sardinia and Corsica (Ovis Musimon L.), which has a coat of brownish red, flecked with darker color; and the slender, long-legged, reddish-gray sheep of Belochistan (Ovis Blanfordi Hume). The first glance at these creatures convinces one that they are wild, not domestic sheep, an impression which is caused chiefly by the monotonous coloring and the dry, short coat, which bears no resemblance to the thick fleece of the tame sheep, although the eye is soon attracted by other differences, such as the shape of the tail, which is short and thick, and of the horns, which extend over the back and then turn inward, so that when the old ram is kept in captivity, it is necessary to cut off the points of the horns to prevent their boring into the flesh of its neck. Horns of this shape form a strong contrast to those with snail-like windings and points standing away from the body. When looking at one of these sheep from the front, it will be noticed that the left horn turns to the right and the right horn to the left.



Former authorities have been unwilling to admit that the domestic sheep have come from any species of wild sheep of the present time. They hold that they are the descendants of one or more species of wild sheep that are now extinct. Recently, however, men have thought more deeply and freely on such subjects, and Nehring and others have traced the modern tame sheep back to the mouflon, but not to him alone. It is thought that in this case, as with other domestic animals, there has been a mixture of species, and in this connection attention was directed to the Transcaspian arkal, the argalis of the interior of Asia and the North African species. Dr. Heck, director of the Berlin Zoological Garden, thinks that the horns of the tame ram, which are turned outward, the points being directed away from the body, constitute one of the strongest proofs that the blood of the argalis and its extinct European ancestors—which are known only by the fossil remains—flows in the veins of all domestic sheep.

The other characteristic marks of the domestic sheep—the wool and the length of the tail—vary greatly. The heath sheep—the little, contented, weather-hardened grazing sheep of the Lueneburg and other heaths—belong to one of the oldest species, and their tails are as short and their horns as dark as those of the moufflon. A cross between these two breeds is not distinguishable, even in the second generation, as has been shown by the interesting experiments in the Duesseldorf Zoological Garden.



The little, black and red-spotted Cameroons sheep, from the western coast of Africa, have not a trace of wool. But why should they have? The negroes need no clothing, and, consequently, they have not bred sheep with wool; and, besides, such an animal could not live in the tropics, even if the black man were a much better stock raiser and breeder than he is. The mane on the neck, and breast of the Cameroons ram reminds one of the North American sheep; but it must be remembered that the mouflon and arkal rams have this ornament quite clearly, although not so strongly defined.



The large, short-bodied and long-legged sheep found in the interior of western and northern Africa are a complete contrast to the short-legged, long-bodied little Cameroons sheep. There is a very valuable pair of the former in the Berlin Zoological Garden—the Haussa sheep—which are very regularly marked, the front parts of their bodies being red and the hind parts white. They were brought from the neighborhood of Say, on the middle Niger, by the Togo Hinterland expedition. The ram has beautiful horns, and the ewe is distinguished by two strange, tassel-like pendants of skin that hang from her neck. This zoological garden also possesses a fine ram from the interior of Tunis, which is similar in shape to the Haussa ram, but has shorter horns and a heavier mane. Its color is grayish black.



Dr. Heck considers the long tail of the domestic sheep the chief impediment to the adoption of the theory of its descent from the short-tailed wild sheep. And yet, in sheep, this member is of secondary importance, for it varies greatly in form. The short-tailed heath sheep are just the opposite of the fat-tailed Persian sheep, which are represented in a fabulous account as being obliged to draw their broad tails, that weighed 40 pounds, behind them on wheels. These are the sheep that supply the Astrakan and Persian lamb which is so much worn now. The fur is caused to lie in peculiar waves or tight rings by sewing the newly born lamb in a tightly fitting covering which keeps the fur from being mussed. In the Berlin Zoological Garden there is a very fine four-horned, fat-tailed ram, from the steppes on the lower Volga. From this region come also the large-boned, fat-rumped sheep, which have a large mass of fat on each side of the stunted tail. In the illustration this peculiarity does not show well, on account of the thick winter wool. Their color is red, with dirty white. When Wissman and Bumiller returned from their last expedition, they brought a fine ram of a different breed of fat-rumped sheep, which are raised by the Kirghise, on the Altai Mountains. They are smaller than those from the steppes of the Volga, but have finer wool, and evidently belong to a finer breed. As mutton tallow is very useful, and has been used even from the most ancient times by sheep raisers in the preparation of food, they prize sheep with these masses of fat on the tail and rump, which were purposely developed to the greatest possible degree.



The steinbock and the chamois, which live in the highest mountains, are still found, but other breeds, such as the argalis, which inhabited the foot hills and the high table lands, have disappeared, as Europe has become more thickly populated. We know that they formerly lived there, by the fossil remains of the oldest Pliocene in England (Ovis Savinii Newton), of the caves of bones near Stramberg in Moravia (Ovis argaloides Nehring), and of the diluvial strata near Puy-de-Dome Mountain in the south of France (Ovis antiqua Pommerol).

For the above and the accompanying illustrations we are indebted to Daheim.

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[Continued from SUPPLEMENT, No. 1172, page 18756.]



PATENTS.[1]

[Footnote 1: To be presented at the Niagara Falls meeting (June, 1898) of the American Society of Mechanical Engineers, and forming part of Vol. six of the Transactions.]

By JAMES W. SEE, Hamilton, Ohio, Member of the Society.

EMPLOYERS' RIGHTS.

An invention, to be patented, must be applied for by the actual inventor, and in the absence of acts constituting a transfer, the patent, and all legal ownership in it, and all rights under it, go exclusively to the inventor. In the absence of express or implied contract, a mere employer of the inventor has no rights under the patent. Only contracts or assignments give to the employer, or to anyone else, a license or a partial or entire ownership in the patent. The equity of this may be appreciated by examples. A journeyman carpenter invents an improvement in chronometer escapements and patents it. The man who owns the carpenter shop has no shadow of claim on or under this patent. Again, the carpenter invents and patents an improvement in jack planes. The shop owner has no rights in or under the patent. Again, the carpenter invents an improvement in window frames, and the shop owner has no rights. He has no right even to make the patented window frame without license. The shop owner, in merely employing the carpenter, acquires no rights to the carpenter's patented inventions. But there are cases in which an implied license would go to the shop owner. For instance, if the carpenter was employed on the mutual understanding that he was particularly ingenious in devising carpenter work, and capable of improving upon the products of the shop; and if in the course of his work he devised a new and patentable window frame, and developed it in connection with his employment and at the expense of his employer; and if the new frames were made by the employer without protest from the carpenter, the carpenter could, of course, patent the new frame, but he could not oust the employer in his right to continue making the invention, for it would be held that the employer had acquired an implied license.

If he could not use it, then he would not be getting the very advantage for which he employed this particular carpenter, and if he did get that right, he would be getting all that he employed the carpenter for, and that right would not be at all lessened by the fact that the carpenter had a patent under which he could license other people. The patent does not constitute the right to make or use or sell, for such right is enjoyed without a patent. The patent constitutes the "exclusive" right to make, sell or use, and this the shop owner does not get unless he specially bargains for it. Implied licenses stand on delicate ground, and where men employ people of ingenious talent, with the understanding that the results of such talent developed during the employment shall inure to the benefit of the employer, there is only one safeguard, and that is to found the employment on a contract unmistakably setting forth the understanding.

NEW PURPOSE.

If an invention is old, it is old regardless of any new purpose to which it is put. It is no invention to put a machine to a new use. If an inventor contrives a meritorious machine for the production of coins or medals, his invention is lacking in novelty if it should appear that such a machine had before been designed as a soap press, and this fact is not altered by any merely structural or formal difference, such as difference in power or strength, due to the difference in duty. The invention resides in the machine and not in the use of it. If the soap press is covered by an existing patent, that patent is infringed by a machine embodying that invention, regardless of whether the infringing machine be used for pressing soap or silver. And it is no invention to discover some new capacity in an old invention. An inventor is entitled to all the capacities of his invention.

COMBINATION CLAIMS.

Many people have an erroneous notion regarding patent claims, and consider the expression "combination" as an element of weakness. The fact is, that all mechanical claims that are good for anything are combination claims. No claim for an individual mechanical element has come under my notice for many years and I doubt if a new mechanical element has been lately invented. All claims resolve themselves into combinations, whether so expressed or not. Combination does not necessarily imply separateness of elements. The improved carpet tack is after all but a peculiar combination of body and head and barbs. The erroneous public contempt for combination claims is based upon the legal maxim, that if you break the combination you avoid the claim and escape infringement, and this legal maxim should be well understood in formulating the claims. If the claim calls for five elements and the competitor can omit one of the elements, he escapes infringement. Therefore, the claim is good only when it recites no elements which are not essential.

Many inventors labor under the delusion that a claim is strong in proportion to the extent of its array of elements. The exact opposite is the truth, and that claim is the strongest which recites the fewest number of elements. It is the duty of the inventor to analyze his invention and know what is and what is not essential to its realization. It is the duty of the patent solicitor to sift out the essential from the non-essential, and to draft claims covering broad combinations involving only essential elements. Sometimes the inventor will help him in this matter, but quite as often he will, through ignorance, hinder him and combat him. The invention having been carefully analyzed and reduced to its prime factors, and the claim having been provided to comprise a combination involving no element which is not essential to a realization of the invention, a new and more important question arises. The elements have been recited in terms fitted to the example of the invention thus far developed. The combination is broadly stated, but the terms of the elements are limiting. Cannot some ingenious infringer realize the invention by a similar combination escaping the literalism of the terms of the elements? It is at this stage that the claim must be carefully studied. The inventor, or some one for him, must assume the position of a pirate, and set his wits to work to contrive an organization realizing the invention but escaping the terms of the proposed claim. When such an escaping device is schemed out, then the defect in the claim is developed and the claim must be redrawn. In this way every possible escape must be studied so as to secure to the inventor adequate protection for his invention. Solicitors find it difficult to get inventors to do or consider this matter properly, inventors being too often inclined to disparage alternative constructions, the matter being largely one of sentiment founded on the love of offspring.

The wise inventor will recognize the fact that the patent which he proposes to get is the deed to valuable property; that the object of the deed is not to permit him to enter upon the property, for he can do that without the deed, but that it is to keep strangers from entering upon the property; that he desires to enjoy his invention without unauthorized competition; that when the property begins to yield profit it will invite competition; that competitors may make machines worse than or as good as or better than his; and that he can get adequate protection only in a claim which would bar poorer as well as better machines embodying his invention. Briefly, then, all good claims for mechanism are combination claims; the fewer the elements recited, the stronger will the claim be; non-essential elements weaken or destroy the claim; the claim should not be considered satisfactory so long as a way is seen for the escape of the ingenious pirate.

COMBINATIONS AND AGGREGATIONS.

A given association of mechanical elements may be entirely new, but it does not follow that it forms a patentable association, for not all new things are patentable. If the new association is a combination, it is patentable, but if it is a mere aggregation, it is unpatentable. An association may be new and still all of its separate elements may be old, the act of invention lying in the fact that the elements have been so associated with relation to each other as to bring about an improved result, or an improved means for an old result. All new machines are, after all, composed of old elements. The law presupposes that the elements are old, and that the invention resides in the peculiar association of them. If we take a given mechanical element, recognized as having had a certain capacity, and if we then similarly take some other mechanical element and employ it only for its previously recognized capacity, and if we then add the third element for its recognized capacity, we have in the end only an association of three elements each performing its well recognized individual office, and the entire association performing only the sum of the recognized individual elements. Such an association is a mere aggregation, a mere adding together of elements, without making the sum of the results any greater in the association than it was in the individual elements. It is simply adding two to one and getting three as a result. An aggregation is unpatentable. As an illustration, a heavy marble statue of Jupiter is found in the parlor and difficult to move. Ordinary casters are put under its pedestal and it becomes easier to move. Modern anti-friction two-wheeled casters are substituted for the commoner casters, and the statue becomes still easier to move. Casters were never before associated with a statue of Jupiter. Here is a new association, but it is a mere aggregation. The statue of Jupiter has been unmodified by the presence of the casters, and the casters perform precisely the same under the statue of Jupiter that they did under the bedstead. There is no combined result, and there is no patentable combination.

But if an inventor takes a given mechanical element for the purpose of its well recognized capacity, and then associates with it another mechanical element for its recognized capacity, but so associates the two elements that one has a modifying effect upon the capacity of the other element, then the association will be capable of a result greater than the sum of the results for the individual elements. This excessive result is not due to the individual elements, but to the combination of them. One has been added to one and a sum greater than two has been secured. The modification of result may be due merely to the bringing of the two elements together, so that they may mutually act upon each other, or it may be due to the manner or means by which they are joined. In a patentable combination the separate elements mutually act upon each other to effect a modification of their previous individual results, and secure a conjoint result greater than the sum of the individual results. The elements of a combination need not act simultaneously; they may act successively, or some may act without motion. As an illustration, assume an old watch in which there was a stem for setting the hands, and assume another old watch with a stem for winding the spring. If an inventor should make a watch, and provide it with the two stems, he would have only an aggregation. But if he employed but one stem, and so located it that it could be used at will for setting the hands or for winding the spring, then he would have produced a combination. The particular instance just given is not a case of the same number of elements, producing a result in excess of the individual results of the separate elements, but is rather a case of a lesser number of elements, producing a combination result equal to the sum of the previous results of a greater number of elements. A better example would perhaps be a new watch with its two old stems so related that either could be used for setting the hands or for winding the spring.

GENERA AND SPECIES.

An inventor, being the first to produce a given organization, and desiring to patent it, may see at once a patentable variation on the device. In other words, he makes two machines patentably different, but both embodying his main invention. He drafts his broad patent claim to cover both machines. In his patent he must illustrate his invention, and he accordingly shows in the drawings the preferred machine. The two machines represent two species of his generic invention, and for illustration he selects the preferable species. He drafts his generic claim to cover both species, and he follows this with a specific claim relating to the selected species. The question might be asked, If the broad generic claim covers the selected and all other species, why bother with the specific claim, why not rest on the generic claim? The answer is that it might in the future develop that the genus was old, and that the generic claim was invalid, while the specific claim would still be good. The infringer of the specific claim may thus be held notwithstanding the generic claim becomes void. But the inventor cannot claim his second species in his patent. He can claim the genus, and he can claim one species under that genus, but all other species must be covered in separate patents. It is even unwise to illustrate alternative species in a patent for, in case, of litigation, some one of the alternative species might prove to be old. This would have the effect, of course, to destroy the generic claim, but it might possibly have the effect of damaging the specific claim if it should appear that the specific claim was after all merely for a modification as distinguished from a distinct species. Were it not for the danger of broad generic claims being rendered void by discovered anticipations, there would be no need for claiming species, but in view of such possibility it is important to claim one species in the generic patent, and to protect alternative species by other patents.

COMBINATION AND SUB-COMBINATION.

A given machine capable of a given ultimate result having been invented, a claim may be drawn to cover the combination of elements comprised in the machine. Such claim will cover the machine as a whole. But, the fact being recognized that many machines are, after all, composed of a series of sub-machines, and that these sub-machines, in turn, are composed of certain combinations of elements, and that within these sub-machines there are still minor combinations of elements capable of producing useful mechanical results, and that the sub-machines, or some of the subordinate combinations of elements within the sub-machines, might be capable of utilization in other situations than that comprehended by the main machine, it becomes important that the inventor be protected regarding the sub-machines and the minor useful combinations. Claims may be drawn for the combination constituting the main machine, other claims may be drawn for the combinations constituting the operative sub-machines, and claims may be drawn covering the minor useful combinations of elements found within the sub-machines. Each claimed combination must be operative. But secondary claims cannot be made for sub-machines or sub-combinations which are for divisional matter or matter which should be made the subject of separate patents.

MECHANICAL EQUIVALENTS.

Where an inventor produces a new mechanical device for the production of a certain result, he can often see in advance that various modifications of it can be made to bring about the same result, and even if he does not see it he may in the future find competitors getting at the result by a different construction. He analyzes the competing structure, and determines that "it is the same thing only different," and wonders what the legal doctrine of mechanical equivalents means, and asks if he is not entitled to the benefits of that doctrine, so that his patent may dominate the competing machine.

An inventor may or may not be entitled to invoke the doctrine of mechanical equivalents, and the doctrine may or may not cause his patent to cover a given fancied infringement. If an inventor is a pioneer in a certain field, and is the first to produce an organization of mechanism by means of which a given result is produced, he is entitled to a claim whose breadth of language is commensurate with the improvement he has wrought in the art. He cannot claim functions or performance, but must limit his claim to mechanism, in other words, to the combination of elements which produces the new result. His claim recites those elements by name. If the new result cannot be produced by any other combination of elements, then, of course, no question will arise regarding infringement. But it may be that a competitor contrives a device having some of the elements of the combination as called for by the claim, the remaining elements being omitted and substitutes provided. The competing device will thus not respond to the language of the claim. But the courts will deal liberally with the claim of the meritorious pioneer inventor, and will apply to it the doctrine of mechanical equivalents, and will hold the claim to be infringed by a combination containing all of the elements recited in the claim, or containing some of them, and mechanical equivalents for the rest of them. Were it not for this liberal doctrine, the pioneer inventor could gather little fruit from his patent, for the patent could be avoided, perhaps, by the mere substitution of a wedge for the screw or lever called for by the claim. The court, having ascertained from the prior art that the inventor is entitled to invoke the doctrine of equivalents, will proceed to ascertain if the substituted elements are real equivalents. A given omitted element will be considered in connection with its substitute element, and if the substitute element is found to be an element acting in substantially the same manner for the production of substantially the same individual result, and if it be found that the prior art has recognized the equivalency of the two individual elements, then the court will say that the substituted element is a mechanical equivalent of the omitted element, and that the two combinations are substantially the same. This reasoning must be applied to each of the omitted elements for which substitutes have been furnished. In this way justice can be done to the pioneer inventor. But the courts, in exercising liberality, cannot do violence to the language of the claim. The infringer will not escape by merely substituting equivalents for recited elements, but he will escape if he omits a recited element and supplies no substitute, for the courts will not read out of a claim an element which the patentee has deliberately put into the claim, and a combination of a less number of elements than that recited in the claim is not the combination called for by the claim.

It is seldom that the exemplifying device of the pioneer inventor is a perfect one. Later developments and improvements by the original patentee, or by others, must be depended on to bring about perfection of structure. Those who improve the structure are as much entitled to patents upon their specific improvements in the device as was the original inventor entitled to his patent for the fundamental device. These improvers are secondary inventors, and are not entitled to invoke the doctrine of mechanical equivalents. The secondary inventor did not bring about a new result, but his patent was for new means for producing the old result. His patent is for this improvement in means, and his claim will be closely scrutinized in court, and he will be held to it, subject only to formal variations in structure. The justice of thus restricting the claim of the secondary inventor must be obvious, in view of the fact that if the doctrine of mechanical equivalents were applied to his claim, then the fundamental device on which he improved would probably infringe upon it, which would be an absurdity. It is thus seen that the pioneer inventor may have a claim so broad in its terms that its terms cannot be escaped; that he may invoke the doctrine of equivalents and have his claim dominate structures not directly responding to the terms of the claim; that the secondary inventor, who improves only the means, is limited to the recited means and cannot invoke the doctrine of equivalents. But within this general view, sight is not to be lost of the fact that secondary inventors may be pioneers within certain limits. They are not the first to produce the broad ultimate result, but they may be pioneers in radically improving interior or sub-results, and they may thus reasonably ask for the application of the doctrine of equivalents to their claims within proper limits. The matter often becomes quite complicated, for it is sometimes difficult to determine as to what is the result in a given machine, for many machines consist, after all, of a combination of subordinate machines. Thus the modern grain-harvesting machine embodies a machine for moving to the place of attack, a machine for cutting the grain, a machine for supporting the grain at the instant of cutting, a machine for receiving the cut grain, a machine for conveying the cut grain to a bindery, a machine for measuring the cut grain into gavels, a machine for compressing the gavel, a machine for applying the band, a machine for tying the band, a machine for discharging the bundle, a machine to receive the bundles and carry them to a place of deposit, and a machine to deposit the accumulated bundles. The machine would be useful with one or more of these sub-machines omitted, and each machine may be capable of performing its own individual results alone or in other associations. Pioneership of invention might apply to the main machine, or to the sub-machines, or even to the sub-organization within the sub-machines.

(To be continued.)

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[Continued from SUPPLEMENT, No. 1172, page 18764.]



THE DEVELOPMENT OF THE CENTRAL STATION.

By SAMUEL INSULL.[1]

[Footnote 1: Before the Electrical Engineering Department of Purdue University, Lafayette, Ind., May 17, 1898.]

The success of the low-tension system was followed by the introduction of the alternating system, using high potential primaries with the converters at each house, reducing, as a rule, from 1,000 down to either 50 or 100 volts. I am not familiar with the early alternating work, and had not at my disposal sufficient time in preparing my notes to go at any length into an investigation of this branch of the subject; nor do I think that any particular advantage could have been served by my doing so, as it has become generally recognized that the early alternating work with a house-to-house converter system, while it undoubtedly helped central station development at the time, proved very uneconomical in operation and expensive in investment, when the cost of converters is added to the cost of distribution. The large alternating stations in this country have so clearly demonstrated this that their responsible managers have, within the last few years, done everything possible, by the adoption of block converters and three-wire secondary circuits, to bring their system as close as they could in practice to the low-tension direct-current distribution system. I do not want to be understood as undervaluing the position of the alternating current in central station work. It has its place, but to my mind its position is a false one when it is used for house-to-house distribution with converters for each customer. The success of the oldest stations in this country, and the demonstration of the possibilities of covering areas of several miles in extent by the use of the three wire system, resulted in much capital going into the business. One of the earliest stations of a really modern type installed on either side of the Atlantic was built by the Berlin Electricity Works. The engineers of that station, while recognizing the high value of the distributing system, went back to Edison's original scheme of a compact direct-connected steam and electric generator, but with dynamos of the multipolar type designed and built by Siemens & Halske, of Berlin, the engines being of vertical marine type.

This was followed by the projecting in New York of the present Duane Street station, employing boilers of 200 pounds pressure, triple and quadruple expansion engines of the marine type, and direct-connected multipolar dynamos. Almost immediately thereafter, the station in Atlantic Avenue, Boston, somewhat on the same general design so far as contents is concerned, was erected. In 1891 a small station, but on the same lines, was projected for San Francisco, and in 1892 the present Harrison Street station of the Chicago Edison company was designed, and, benefiting by the experience of Berlin, New York and Boston, this station produces electric current for lighting purposes probably cheaper than any station of a similar size anywhere in this country.

It is not necessary for me to go into detail in explanation of the modern central station. You are all doubtless quite familiar with the general design, but if you will examine the detail drawings of the Harrison Street station, which I have brought with me, you will find that every effort has been made to provide for the economical production of steam, low cost of operating, good facilities for repairs and consequently low cost, and for permanency of service. You have but to go into any of the modern central stations in midwinter, to see them turning out anywhere from 10,000 to 80,000 amperes with a minimum of labor, to appreciate the fact that central station business is of a permanent and lucrative character.

To go back to the question of alternating currents, the work done in connection with the two-phase and three-phase currents and the perfection of the rotary transformer has resulted in introducing into central station practice a further means of economizing the cost of production—by concentration of power. According to present experience, it is (except in some extraordinary cases) uneconomical to distribute direct low-tension current over more than a radius of a mile and a half from the generating point. The possibility of transmitting it at a very high voltage, and consequently low investment in conductors, has resulted in the adoption of a scheme, in many of the large cities, of alternating transmission combined with low tension distribution. The limit to which this alternating transmission can be economically carried has not yet been definitely settled, but it is quite possible even now to transmit economically from the center of any of our large cities to the distant suburbs, by means of high potential alternating currents, distributing the current from the subcenter distribution by means either of the alternating current itself and large transformers for a block or district or else, if the territory is thickly settled, by means of a system of low-tension mains and feeders, the direct current for this purpose being obtained through the agency of rotary transformers.

There are various methods of producing the alternating current for transmission purposes. In some cases the generators are themselves wound for high potential; in others they are wound for 80 volts, and step-up transformers are used, carrying the current up to whatever pressure is desired, from 1,000 to 10,000 volts. In other cases dynamos are used having collector rings for alternating current on one side and a commutator for direct current on the other side of the armature, thus enabling you, when the peak in two districts of a city comes at two different times, to take care of this peak by means of the same original generating unit, furnishing direct low-tension current to the points near the central station and alternating current to the distant points. In other cases, where a small amount of alternating current is required on the transmission line, it has even been found economical to take direct current from a large unit, change it by means of a rotary transformer into alternating current, step up from 80 to, say, 2,000 volts, go to the distant point, and step down again to 80 volts alternating, and then convert again by means of a rotary transformer into low-potential direct current.

The introduction of alternating current for transmission purposes in large cities is probably best exemplified in the station recently erected in Brooklyn, where alternating current is produced and carried to distant points, and then used to operate series arc-light machines run by synchronous motors, the low-tension direct-current network being fed by rotary transformers, and alternating circuits arranged with block converters, and even in some cases separate converters for each individual customer in the scattered districts.

It would be very interesting to go at length into the details of cost in this, the latest development of central station transmission, but time will not permit; nor have I the time at my disposal to go at length into the central station business as developed by the electric street railways now so universally in use, or another phase of the business as exemplified by the large transmission plants, the two greatest examples of which, in this country, are probably those at Niagara Falls, N.Y., and Lachine Rapids, near Montreal. So far as street railways and power transmission are concerned, I would draw your attention to the fact that the same underlying principle of multiple-arc mains and feeders originally conceived by Mr. Edison is as much a necessity in their operation as it is in the electric lighting systems, whether those systems be operated on the old two-wire plan, the three-wire plan or by means of alternating currents.

Passing from a review of central station plants and distribution system naturally bring us to the operating cost and the factors governing profit and loss of the enterprise. In considering this branch of the subject, I will confine my remarks to the business as operated in Chicago by the company with which I am connected.

Our actual maximum last winter came on December 20, our load being approximately 12,000 horse power. A comparison of the figures of maximum capacity and maximum load of last winter shows that we had a margin in capacity over output of about 20 per cent. The load curves shown this evening represent the maximum output of last winter (December 20), an average summer load last year (June 4), and an average spring load of this year (May 2). For our purposes we will assume the maximum capacity of the plant and the maximum load of the system to be identical. The maximum load last winter occurred, as I have stated, on December 20, about 4:30 o'clock in the afternoon, and lasted less than half an hour. It should be borne in mind that the period of maximum load only lasts for from two to three months, and that the investment necessary to take care of that maximum load, has to be carried the whole year. It should not be assumed from this statement that the whole plant as an earning factor is in use 25 per cent. of the year. The fact is that, during the period of maximum load, the total plant is in operation only about 100 hours out of the 8,760 hours of the year; so that you are compelled, in order to get interest on your investment, to earn the interest for the whole of the year in about 11/2 per cent. of that period, on about 50 per cent. of your plant.

This statement must bring home to you a realization of the fact that by far the most serious problem of central station management, and by far the greatest item of cost of your product, is interest on the investment. It may be that the use of storage batteries in connection with large installations will modify this interest charge, but even allowing the highest efficiency and the lowest cost of maintenance ever claimed for a storage battery installation, the fact of high interest cost must continue to be the most important factor in calculating profit and loss. This brings home to us the fact that in his efforts to show the greatest possible efficiency of his plant and distribution system, it is quite possible that the station manager may spend so much capital as to eat up many times over in interest charge the saving that he makes in direct operating expenses. It is a common mistake for the so-called expert to demonstrate to you that he has designed for you a plant of the highest possible efficiency, and at the same time for him to lose sight of the fact that he has saddled you with the highest possible amount of interest on account of excessive investment. Operating cost and interest cost should never be separated. One is as much a part of the cost of your current as the other. This is particularly illustrated in connection with the use of storage batteries. Those opposed to their use will point out to you that of the energy going into the storage battery only 70 per cent. is available for use on your distribution system. That statement in itself is correct; but in figuring the cost of energy for a class of business for which the storage battery is particularly adapted, the maximum load, that portion of your operating cost affected by the 30 per cent. loss of energy in the battery, forms under 41/2 per cent. of your total cost, and it must be self-evident, in that case at least, that the 30 per cent. loss in the storage battery is hardly an appreciable factor in figuring the operating cost of your product. So far as I have been able to ascertain, it would appear to be economical to use storage batteries in connection with central station systems the peak of whose load does not exceed from two to two and one-half hours.

In order to illustrate the important bearing which interest has on cost, I have prepared graphical representations of the cost of current, including interest, under conditions of varying load factors. For the purpose of this chart I have assumed an average cost of current, so far as operating and repairs and renewals and general expense are concerned, extending over a period of a year, although of course these items are more or less attested by the character of the load factor. For the purpose of figuring interest, I have selected seven different classes of business commonly taken by electric light and power companies in any large city. Take, for instance, an office building. It has a load factor of about 3.7 per cent., that is, the average load for the whole year is 3.7 per cent. of the maximum demand on you for current at any one time during that period; or, to put it in another way, this load factor of 3.7 per cent. would show that your investment is in use the equivalent of a little over 323 hours a year on this class of business. This is by no means an extreme case. You can find in almost every large city customers whose load factors are not nearly as favorable to the operating company, their use of your investment being as low as the equivalent of 75 or 100 hours a year. Take another class of business, that of the haberdasher, or small fancy goods store. As a rule these stores are comparatively small, with facilities for getting a large amount of natural light and little use for artificial light. The load factor as shown by the chart is about 7 per cent., the use of your investment being not quite twice as long as that of the office building. Day saloons show an average of 16 per cent. load factor; cafetiers and small lunch counters about 20 per cent., while the large dry goods stores, in which there is comparatively little light, have a load factor of 25 per cent. and use your investment seven times as long per year as the office building. Power business naturally shows a still better load factor, say 35 per cent., and the all-night restaurant has a load factor of 48 per cent.

You will see from this that the great desideratum of the central station system is, from the investors' point of view, the necessity of getting customers for your product whose business is of such a character as to call for a low maximum and long average use. This question of load factor is by all means the most important one in central station economy. If your maximum is very high and your average consumption very low, heavy interest charges will necessarily follow. The nearer you can bring your average to your maximum load, the closer you approximate to the most economical conditions of production, and the lower you can afford to sell your current. Take, for instance, the summer and winter curves of the Chicago Edison company. The curve of December 20, 1897, shows a load factor of about 48 per cent.; the curve of May 2, 1898, shows a load factor of nearly 60 per cent. Now, if we were able in Chicago to get business of such a character as would give us a curve of the same characteristics in December as the curve we get in May; or, in other words, if we could improve our load factor, our interest cost would be reduced, an effect would be produced upon the other items going to make up the cost of current, and we probably could make more money out of our customers at a lower price per unit than we get from them now.

Many schemes are employed for improving the load factor, or, in other words, to encourage a long use of central station product. Some companies adopt a plan of allowing certain stated discounts, provided the income per month of each lamp connected exceeds a given sum. The objection to this is that it limits the number of lamps connected. Other companies have what is known as the two-rate scheme, charging one rate for electricity used during certain hours of the day and a lower rate for electricity used during the balance of the day, using a meter with two dials for this purpose. Other companies use an instrument which registers the maximum demand for the month, and the excess over the equivalent of a certain specified number of hours monthly in use of the maximum demand is sold at greatly reduced price. The last scheme would seem particularly equitable, as it results in what is practically an automatic scale of discounts based on the average load factor of the customers. It does not seem to be just that a man who only uses your investment say 100 hours a year should be able to buy your product at precisely the same price as the man who uses your investment say 3,000 hours a year, when the amount of money invested to take care of either customer is precisely the same. Surely the customer who uses the product on an average 30 times longer than the customer using it for only 100 hours is entitled to a much lower unit rate, in view of the fact that the expense for interest to the company is in one case but a fraction per unit of output of what it is in the other. This fact is illustrated by the interest columns on the graphic chart already referred to. Supposing that the central station manager desired to sell his product at cost, that is, an amount sufficient to cover his operating, repairs and renewals, general expense, and interest and depreciation, he would have to obtain from the customer having the poorest load factor, as shown on the load chart, over four times as much per unit of electricity as it would be necessary for him to collect from the customer having the largest load factor. No one would think of going to a bank to borrow money and expect to pay precisely the same total interest whether he required the money for one month or for twelve; and for the same reason it seems an absurdity to sell electricity to the customer who uses it but a comparatively few hours a year at the same price at which you would sell it to the customer using it ten hours a day and three hundred days a year, when it is remembered that interest is the largest factor in cost, and the total amount of interest is the same with the customer using it but a few hours a year as it is with the customer using it practically all the year around.

I have dwelt thus at length on the question of interest cost in operating a central station system, not alone for the purpose of pointing out to you its importance in connection with an electrical distribution system, but also to impress upon you its importance as a factor in cost; in fact, the most important factor in cost in any public service business which you may enter after leaving this institution. Most of the businesses presenting the greatest possibilities from the point of view of an engineering career are those requiring very large investment and having a comparatively small turnover or yearly income. Of necessity, in all enterprises of this character, the main factor of cost is interest, and if you intend following engineering as a profession, my advice to you would be to learn first the value of money, or, to put it another way, to learn the cost of money.

Before leaving this question of interest and its effect upon cost, I would draw your attention to the fact that while interest is by far the most important factor of cost, it is a constantly reducing amount per unit of maximum output in practically every central station system. When a system is first installed, it is the rule to make large enough investment in real estate and buildings to take care of many times the output obtained in the first year or so of operation. As a rule, the generating plant from the boilers to the switchboard is designed with only sufficient surplus to last a year or so. In the case of the distributing system the same course is followed as in the case of real estate and buildings, with a view to minimizing the ultimate investment. Mains are laid along each block facing, feeders are put in having a capacity far beyond the necessity of the moment; consequently interest cost is very high when a plant first starts, except, as I have stated, in the case of the machinery forming the generating plant itself. As the business increases from, year to year, the item of interest per unit of maximum output consequently will constantly decrease, owing to the fact that each additional unit of output following an increase of connected load increases the divisor by which the total interest is divided. The result is from year to year the interest cost of each additional unit of maximum output is a constantly reducing amount, and consequently the average interest cost of each unit of maximum output should, in a well regulated plant, grow less from year to year until the minimum interest cost per unit is reached. This minimum interest cost is reached when the capacity of the whole system and the total units of output at maximum load are identical, although of course it will always be necessary to have a certain margin of capacity over possible output, as a factor of safety.

This same rule, although to a less extent, applies to the operating and general expense cost, that is, the cost other than interest. To particularize, the manager's salary and other administrative expenses do not increase in proportion to maximum output of station; therefore, the cost of administration per unit of output, if the business is in a healthy condition, must be from year to year reduced. There are a great many other expenses that are not directly in proportion to output, and these follow the same rule. In a well-run plant the percentage of operating expenses to gross receipts will stand even year after year, while the income per unit of output will be constantly reduced. This is an excellent evidence of the fact that the cost per unit of output is constantly being reduced, as, if it were not, the percentage of expenses to gross receipts would be increased in direct proportion to the reduction in price. Moreover, it should be borne in mind that there are many difficulties in the way of universal use of electric energy from a central station system. It is the rare exception to find a house not piped for gas and water. In the case of the latter it is almost invariably the rule that owners are compelled to pipe for water, under the sanitary code of the municipality. On the other hand, in a large residential district, it is the exception to find a house wired for electric light; consequently the output of current per foot of conductor is at the present time very low as compared with the output of gas per foot of gas pipe in any of the large cities. The expense of wiring (which must of necessity be borne by the householder) is large, and it is often a barrier to the adoption of electric illumination, but as the rule to wire houses becomes more general, the output per foot of main will constantly increase, and therefore the interest per unit of output per foot of main will constantly decrease. This same rule will apply in the case of expenses of taking care of and repairing the distribution system, although to not so great an extent.

If you will take into account these various factors constantly operating toward a reduction of operating and general expense cost, and interest cost, the conclusion must necessarily be forced upon you that the price at which current can be sold at a profit to-day is in no sense a measure of the income per unit which it will be necessary for central station managers to obtain in the future. In 1881-82 it was difficult to make both ends meet with an income of 25 cents per kilowatt hour, to-day there are many stations showing a substantial return on their investment whose average income does not exceed 7 cents per kilowatt hour, showing 70 per cent. reduction in price in less than two decades. How far this constant reduction in cost, followed by a constant reduction in selling price, will go, it is difficult to determine; but if so much has been accomplished during the first 20 years of the existence of the industry, is it too much to predict that in a far less time than the succeeding 20 years electric current for all purposes will be within the reach of the smallest householder and the poorest citizen? But few industries can parallel the record already obtained. If you will trace the history of the introduction of gas as an illuminant, you will find that it took a much longer time to establish it on a commercial basis than it has taken to establish most firmly the electric lighting industry. All the great improvements in gas, the introduction of water gas, the economizing in consumption by the use of the Welsbach burner, have all been made within the time of those before me, and yet, notwithstanding that when these gas improvements started, the electric lighting business was hardly conceived, and certainly had not advanced to a point where you could claim that it had passed the experimental stage—notwithstanding this, the cost of electrical energy has decreased so rapidly that to-day there are many large central station plants making handsome returns on their investments at a far lower average income per unit of light than the income obtained by the gas company in the same community. In making my calculations which have led me to this conclusion, I have assumed that 10,000 watts are equal to 1,000 feet of gas. This comparison holds good, provided an incandescent lamp of high economy is used as against the ordinary gas burner. To make a comparison between electric illumination and incandescent gas burners, such as the Welsbach burner, you must figure on the use of an arc lamp in the electric circuit instead of an incandescent lamp, which is certainly fair when it is remembered that incandescent gas burners are, as a rule, used in places where arc lamps should be used if electric illumination is employed.

With such brilliant results obtained in the past, the prospects of the central station industry are certainly most dazzling. While the growth of the business has been phenomenal, more especially since 1890, I think it can be conservatively stated that we have scarcely entered upon the threshold of the development which may be expected in the future. In very few cities in the United States can you find that electric illumination exceeds more than 20 per cent. of the total artificial illumination for which the citizens pay. If this be the state of affairs in connection with the use of electricity for illuminating purposes, and if you will bear in mind the many other purposes to which electricity can be adapted throughout a city and supplied to customers in small quantities, you may get some faint conception of the possible consumption of electrical energy in the not far distant future. Methods of producing it may change, but these methods cannot possibly go into use unless their adoption is justified by saving in the cost of production—a saving which must be sufficient to show a profit above the interest and depreciation on the new plant employed. It is within the realms of possibility that the present form of generating station may be entirely dispensed with. It has already been demonstrated experimentally that electrical energy may be produced direct from the coal itself without the intervention of the boiler, engine and dynamo machine. Whether this can be done commercially remains to be proved. Whatever changes may take place in generating methods, I should, were I not engaged in a business which affords so many remarkable surprises, be inclined to question the possibility of any further material change in the distributing system. Improvements in the translating devices, such as lamps, may add enormously to the capacity of the distributing system per unit of light; but it does seem to me that the system itself, as originally conceived, is to a large extent a permanency. Should any great improvements take place in the medium employed for turning electrical energy into light, the possible effect on cost, and consequently selling price, would be enormous.

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THE PROPOSAL of Gov. Black, which has now become law, to depute to Cornell the care of a considerable tract of forest land, and the duty of demonstrating to Americans the theory, methods and profits of scientific forestry, has a curious appropriateness much commented on at the university, since two-thirds of the wealth of Cornell has been derived from the location and skillful management of forest lands, the net receipts from this source being to date $4,112,000. In the course of twenty years management the university has thrice sold the timber on some pieces of land which it still holds, and received a larger price at the third sale than at the first. The conduct of this land business is so systematized that the treasurer of the university knows to a dot the amount of pine, hemlock, birch, maple, basswood and oak timber, even to the number of potential railroad ties, telegraph poles and fence posts on each fourth part of a quarter section owned by Cornell. Certainly, Cornell is rich in experience for the business side of a forestry experiment such as Gov. Black proposes. The university forest lands from which its endowment has been realized are in Wisconsin.

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Books may be called heavy when the qualifying term is not applied to their writers, but to the paper makers. It is falsifications in the paper that give it weight. Sulphate of baryta, the well known adulterate of white lead, does the work. A correspondent, writing to The London Saturday Review, gives the weight of certain books as: Miss Kingsley's "Travels in Africa." 3 pounds 5 ounces; "Tragedy of the Caesars," 3 pounds; Mahan's "Nelson" (1 vol.), 2 pounds 10 ounces; "Tennyson" (1 vol.), 2 pounds 6 ounces; "Life and Letters of Jowett" (1 vol.), 2 pounds 1 ounce. To handle these dumb-bell books, The Saturday Review advises that readers take lessons in athletics.

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THE LOCK OF THE DORTMUND-EMS CANAL AT HENRICHENBURG.

The Dortmund-Ems Canal, destined to connect the heart of German industry with the sea, was formally dedicated on April 1, and partially opened to commerce. After its completion, German coal will be transported to the harbors of the Ems at the same cost as the English coal which has hitherto forced back the treasures of our soil; our black diamonds will then be sold in the markets of the world, and the Kaiser Wilhelm Canal will enable the western part of the empire to exchange its coal and iron for the grain and wood of the East.

Many difficulties were encountered in cutting the canal, owing partly to the vast network of railroads in the coal region of Westphalia, but chiefly due to the insufficiency of moisture in the highlands, the latter not containing enough water to supply the many necessary sluices, at which it could be easily foreseen considerable traffic would occur.



For the modern engineer there are, however, no insurmountable obstacles. Instead of a line of ordinary locks, a single structure was erected sufficient for the needs of the entire region. This lock is situated at Henrichenburg, near Dortmund, and our illustration pictures it with its lock-chamber half raised.

The lock, which serves to overcome a difference in level of fifty-nine feet, raises vessels of 1,000 tons capacity with a velocity of 0.3 to 0.7 foot per second, and has been constructed after a new and astonishingly simple system.

The lock chamber, designed for the reception of the various vessels, is 229.60 feet in length and 28.864 feet in breadth and normally contains 8.2 feet of water. Under the sluice in a line with the long axis are five wells filled with water in which cylindrical floats are placed, connected to the bottom of the chamber by means of iron trellis-work. The floats are placed so deeply that, in their highest position, their upper edges are always submerged; they are, moreover, of such size that by means of their upward impulsion the chamber is held in equilibrium. Irrespective of the small differences of pressure which arise from the varying immersion of the framework, the lock will in all positions be in equilibrium. Since a vessel which enters the lock displaces a volume of water whose weight is equal to the weight of the vessel, a constant equilibrium will always be maintained and only a minimum force required to raise or lower the chamber. In order to move the lock-chamber up and down and to sustain it constantly in a horizontal position, nuts have been fixed to strong crossbeams, through which powerful screw-rods work.

These rods are held in place by a massive framework of iron and are turned to the left or to the right by means of a small steam engine, placed at one side of the lock, which engine, by means of a longitudinal shaft, drives two cross shafts to which bevel wheels are attached. By this means the chamber is lowered and raised. The screw rods are so powerful that they sustain the entire weight of the lock chamber, and the pitch of the thread is such that spontaneous sliding or slipping is impossible, the chamber being, therefore, kept constantly in the desired position.

It is interesting to note that the hollow space in the screw rods is heated by steam during winter, thus preventing the formation of ice in the machinery.

During the eighties, locks for ships of 400 tons capacity were erected in England and France, at Anderton, Les Fontinettes and La Louviere. The lock at Henrichenburg, however, exceeds all its predecessors, not only in size, but also in security. At all events, the structure is a worthy memorial of the energy and genius of German engineers.—Illustrirte Zeitung.

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Paper hanging by machine is the latest achievement, according to a German contemporary, says The Engineer. The arrangement used for this purpose is provided with a rod upon which the roll of paper is placed. A paste receptacle with a brushing arrangement is attached in such a manner that the paste is applied automatically on the back of the paper. The end of the wall paper is fixed at the bottom of the wall and the implement rises on the wall and only needs to be set by one workman. While the wall paper unrolls and, provided with paste, is held against the wall, an elastic roller follows on the outside, which presses it firmly to the wall. When the wall paper has reached the top, the workman pulls a cord, whereby it is cut off from the remainder on the roll.

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THE AMERICAN "REGULAR."

BY THE ENGLISH CORRESPONDENT OF THE LONDON TIMES ON BOARD THE UNITED STATES TRANSPORT "GUSSIE."

The "regular" of the United States is in many respects the least equipped foot soldier of my acquaintance. This was my reflection as I overhauled the kit of a private this morning on board the "Gussie." There was not a single brush in his knapsack. I counted three in that of a Spanish foot soldier only a few weeks ago. The American knapsack is merely a canvas bag cut to the outward proportions of the European knapsack, but in practical features bearing affinity with the "rueckensack" of the Tyrolean chamois hunters, or pack-sack of the backwoodsmen of Canada and the Adirondack Mountains. This knapsack of the American is not intended to be carried on any extended marches, although the total weight he is ever called upon to carry, including everything, is only 50 pounds, a good 12 pounds less than what is carried by the private of Germany. The men of this regiment, in heavy marching order, carry an overcoat with a cape, a blanket, the half of a shelter tent, and one wooden tent pole in two sections. The rifle could be used as a tent pole—so say men I talk with on the subject. On this expedition overcoats are a superfluity, and it is absurd that troops should be sent to the tropics in summer wearing exactly the same uniform they would be using throughout the winter on the frontiers of Canada. This war will, no doubt, produce a change after English models. At present the situation here is prevented from being painful because no marching has yet been attempted, and the commanding officers permit the most generous construction in the definition of what is a suitable uniform.

On the trip of this ship to Cuba, no officer or man has ever worn a tunic excepting at guard mounting inspection. The 50 men who went ashore near Cabanas on May 12 and pitched into some 500 Spaniards left their coats behind and fought in their blue flannel shirts. Of the officers, some wore a sword, some did not, though all carried a revolver. No orders were issued on the subject—it was left to individual taste, I have experienced hotter days at German maneuvers than on the coast of Cuba during the days we happened to be there, yet I have never noticed any disposition in the army of William II. to relax the severity of service even temporarily. My German friends sincerely believe that the black stock and the hot tunic are what has made Prussia a strong nation, and to disturb that superstition would be a thankless task.

In the way of clothing the American private carries a complete change of under-drawers, under-shirt, socks, laced boots and uniform trousers. My particular private was carrying a double allowance of socks, handkerchiefs, and underwear. He had a toothbrush and comb. That is the heavy marching order knapsack. For light marching, which is the usual manner, the man begins by spreading on the ground his half-tent, which is about the size of a traveling rug. On this he spreads his blanket, rolls it up tightly into a long narrow sausage, having first distributed along its length a pair of socks, a change of underwear, and the two sticks of his one tent pole. Then he brings the ends of this canvas roll together, not closely, as in the German army, but more like the ends of a horse-shoe, held by a rope which at the same time stops the ends of the roll tightly. When this horse shoe is slung over the man's shoulder, it does not press uncomfortably upon his chest. The total weight is distributed in the most convenient manner for marching.

The packing of the man's things is strictly according to regulation, excepting only the single pocket in his knapsack, where he may carry what he chooses, as he chooses. His light canvas haversack is much like the English one, and his round, rather flat water flask is covered with canvas. It is made of tin, and the one I inspected was rusty inside. It would be better if of aluminum. In the haversack is a pannikin with a hinged handle that may be used as a saucepan. Over this fits a tin plate, and when the two are covering one another the handle of the pannikin fits over both by way of handle. It is an excellent arrangement, but should be of aluminum instead of a metal liable to rust. The most valuable part of this haversack is a big tin cup that can be used for a great variety of purposes, including cooking coffee. It is hung loose at the strap of the haversack. Of course each man has knife, fork and spoon, each in a leather case.

The cartridge belt contains 100 rounds, which are distributed all the way around the waist, there being a double row of them. The belt is remarkably light, being woven all in one operation. It is of cotton and partly some material which prevents shrinking or loosening. The belts have stood admirably the test put upon them for the last six days, when it has rained every day, on top of the ordinary heavy moisture usual at sea in the tropics. The test is the more interesting from their having been previously in a very dry country. Officers and men alike unite in praise of this cartridge belt. The particular private whom I was inspecting said he now carried 100 as easily as he formerly carried 50. This belt rests loosely on the hips, without any straps over the shoulders. It is eminently businesslike in appearance. The hat is the gray felt of South Africa, Australia, and every other part of the world where comfort and cost are consulted. No boots are blacked on expeditions of this kind. The men who form in line for guard duty have their tunics well brushed, but that may be due to extraneous assistance.

For fighting purposes, then, the United States private has nothing to keep clean excepting his rifle and bayonet. He carries no contrivances for polishing buttons, boots, or the dozen of bits of accouterment deemed essential to a good soldier in Europe. In Spain, for instance, the private, though he may have nothing in his haversack, will, nevertheless, carry a clumsy outfit of tools for making his uniform look imposing.

Now, as to discipline in the American army I cannot speak at present, for the war is yet too young. It may, however, be worth noting that in this particular regiment, while most complete liberty was allowed the men all the twelve days of the rail journey from San Francisco to Tampa, not a single case of drunkenness or any other breach of discipline was reported. Among the 105 men on this boat there has not in the past seven days been a single case of sickness of any kind or any occasion for punishing. The firing discipline during the three times we have been under fire has been excellent; the obedience of soldiers to their officers has been as prompt and intelligent as anything I have seen in Europe; and as to coolness under fire and accuracy of aim, what I have seen is most satisfactory. The men evidently regard their officers as soldiers of equal courage and superior technical knowledge. To the Yankee private "West Pointer" means what to the soldier of Prussia is conveyed by noble rank. In my intimate intercourse with officers and men aboard this ship I cannot recall an instance of an officer addressing a private otherwise than is usual when a gentleman issues an order. I have never heard an officer or noncommissioned officer curse a man. During the engagement of Cabanas the orders were issued as quietly as at any other time, and the men went about their work as steadily as bluejackets on a man-o'-war.

All this I note, because this is the first occasion that United States troops have been in action since the civil war, and because I have more than once heard European officers question the possibility of making an army out of elements different from those to which they were accustomed. I have heard Germans insist that unless the officer appears in uniform he cannot command the respect of his men. On this ship it would be frequently difficult to tell officers from men when the tunic is laid aside and shoulder straps are not seen. There are numberless points of resemblance between Tommy Atkins and the Yankee private; and the Sandhurst man has no difficulty in understanding the West Pointer. But to do this we must go a little beneath the surface and see things, not on the parade ground, but in actual war. For dress occasions the American uniform is far and away the ugliest and most useless of all the uniforms I know. The helmets and cocked hats are of the pattern affected by theatrical managers, the decorations tawdry, the swords absurd, the whole appearance indicative of a taste unmilitary and inartistic. The parade uniform has been designed by a lot of unsoldierly politicians and tailors about Washington. Their notion of military glory is confused with memories of St. Patrick's Day processions and Masonic installations. They have made the patient United States army a victim of their vulgar designs, and to-day at every European army maneuver one can pick out the American military attache by merely pointing to the most unsoldierly uniform on the field. On the battlefield, however, there are no political tailors, and the Washington dress regulations are ruthlessly disregarded.

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STEERING GEAR OF NORTH GERMAN LLOYD STEAMERS "COBLENTZ," "MAINZ," AND "TRIER."

The steering gear illustrated below, which has been fitted to a number of vessels in this country as well as on the three North German Lloyd steamers above named, is designed, primarily, to effect the distribution of the leverage more in proportion to the resistance of the rudder than exists in ordinary gears. The latter, as a rule, exert a uniform and decreasing, instead of an increasing, purchase on the rudder, in moving it from midgear to hard over. This important object is attained in the gear under notice chiefly through the arrangement of the quadrant and the spring buffers, which form an essential part of it, and of the tiller crosshead. The quadrant—which, as may be gathered from our illustration, has its main body formed of wrought steel, flanged and riveted, making an exceptionally strong design—works on its own center. It travels through 51 degrees in moving the tiller crosshead through 40 degrees, and in doing so increases the leverage over the rudder to an extent which is equivalent to a gain of 60 per cent. upon midgear position.



Being carried on its own center, and not, as is usual, on the rudder stock, and with its rim supported on rollers, the quadrant does not impose upon the rudder pintles any of its own weight, thus diminishing the wear on these parts. This arrangement also keeps the quadrant always in good gear with its pinion, thereby allowing the teeth of both to be strengthened by shrouding, and rendering them exempt from the effects of sinking and slogger of the rudder stock as the pintles wear. The rack and pinions are of cast steel, as is also the tiller crosshead. The spring buffers, which, as has been said, form an essential part of the quadrant, are fitted with steel rollers at the point of contact with the crosshead, thereby reducing the friction to a minimum. The springs, by their compression, absorb any shock coming on the rudder, and greatly reduce the vibration when struck by a sea. They are made adjustable, and can be either steel or rubber.

Our illustrations show the arrangement of the gear as worked by hand at the rudder head, but of course gears are made having a steam steering engine as the major portion of the arrangement—the two cylinders being placed directly over the quadrant—thus securing the well known advantages attaching to a direct rudder head steering engine as compared with the engine situated amidship, with all the friction of parts, liability to breakage, etc., thereby entailed.

Whether with engine amidship or directly over the rudderhead, ample provision is made for putting the hand power into gear by means of a friction clutch within the standard upon which the hand wheels are mounted. The clutch is of large diameter and lined with hard wood, power and ready facility being provided by the hand lever—seen at the top of standard—and the screw which it operates, for shifting to in and out of gear.

The patentees and makers of this type of gear are Messrs. Croom & Arthur, Victoria Dock, Leith, who, in addition to fitting it to the three North German Lloyd steamers named in the title—which are each of 3,200 tons, having an 8-inch rudder-stock—have applied it to the Hamburg and Australian liner Meissen of 5,200 tons and 10-inch rudder stock, and to the steamer Carisbrook of 1,724 tons, owned in Leith. On the latter vessel, which was the first fitted with it, the gear has been working for over two years, giving, we are told, entire satisfaction to the owners, who say the spring buffers undoubtedly reduce the vibration when the rudder is struck by a sea, and the arrangement of quadrant and tiller appears to give increase of power. Of the installation of this gear on board the three North German Lloyd vessels, the agents of that company say: "It has been working to our entire satisfaction. This system, on the whole, proves to have answered its purpose." Considering the advantages claimed for the gear, this is satisfactory testimony. We are indebted to The London Engineer for the cuts and description.

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COMBINED STEAM PUMPING AND MOTIVE POWER ENGINE.

We give herewith an illustration of a compact engine, designed by Messrs. Merryweather & Sons, of London, particularly for mining work, and already supplied to the Burma ruby mines, the Salamanca tin mines, and several mining companies in Brazil and other parts of South America. It is an arrangement of the Valiant steam pumping engine with a flywheel arranged to take a belt, and is so constructed that the pump can be readily thrown out of gear and the engine used to drive light machinery. The smaller size weighs only 7 cwt., including boiler, engine and pump complete, and can be run on its own wheels, or these can be detached and the machine carried by eight or ten men on shoulder poles passed through rings fitted on top of the boiler. Thus it can be easily transported up country, and has for this reason been found most useful for prospecting. For alluvial mining it will throw a powerful jet at 100 lb. to 120 lb. pressure, or by means of a belt will drive an experimental quartz crusher or stamp mill. The power developed is six horses, and the boiler will burn wood or other inferior fuel when coal is not obtainable. The pump will deliver 100 gallons per minute, on a short length of hose or piping, and will force water through three or four miles of piping on the level, or, on a short length, 35 gallons per minute against a head of 210 feet. The pump is made entirely of gun metal, with rubber valves, and has large suction and delivery branches. Air vessels are fitted, and the motion work is simple and strong. The boiler is Merryweather's water tube type, and raises steam rapidly, while the fittings include feed pump, injector, safety valve, steam blast and an arrangement for feeding the boiler from the main pump in case of necessity.