Scientific American Supplement, No. 286, June 25, 1881(txt+pdf+epub+mobi电子书下载)


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Scientific American Supplement, No. 286, June 25, 1881

Scientific American Supplement, No. 286, June 25, 1881试读:

PETROLEUM AND COAL IN VENEZUELA.

MR. E. H. PLUMACHER, U. S. Consul at Maracaibo, sends to the State Department the following information touching the wealth of coal and petroleum probable in Venezuela:

The asphalt mines and petroleum fountains are most abundant in that part of the country lying between the River Zulia and the River Catatumbo, and the Cordilleras. The wonderful sand-bank is about seven kilometers from the confluence of the Rivers Tara and Sardinarte. It is ten meters high and thirty meters long. On its surface can be seen several round holes, out of which rises the petroleum and water with a noise like that made by steam vessels when blowing off steam, and above there ascends a column of vapor. There is a dense forest around this sand-bank, and the place has been called "El Inferno." Dr. Edward McGregor visited the sand-bank, and reported to the Government that by experiment he had ascertained that one of the fountains spurted petroleum and water at the rate of 240 gallons per hour. Mr. Plumacher says that the petroleum is of very good quality, its density being that which the British market requires in petroleum imported from the United States. The river, up to the junction of the Tara and Sardinarte, is navigable during the entire year for flat-bottomed craft of forty or fifty tons.

Mr. Plumacher has been unable to discover that there are any deposits of asphalt or petroleum in the upper part of the Department of Colon, beyond the Zulia, but he has been told that the valleys of Cucuta and the territories of the State of Tachira abound in coal mines. There are coal mines near San Antonia, in a ravine called "La Carbonera," and these supply coal for the smiths' forges in that place. Coal and asphalt are also found in large quantities in the Department of Sucre. Mr. Plumacher has seen, while residing in the State of Zulia, but one true specimen of "lignite," which was given to him by a rich land-owner, who is a Spanish subject. In the section where it was found there are several fountains of a peculiar substance. It is a black liquid, of little density, strongly impregnated with carbonic acid which it transmits to the water which invariably accompanies it. Deposits of this substance are found at the foot of the spurs of the Cordilleras, and are believed to indicate the presence of great deposits of anthracite.

There are many petroleum wells of inferior quality between Escuque and Bettijoque, in the town of Columbia. Laborers gather the petroleum in handkerchiefs. After these become saturated, the oil is pressed out by wringing. It is burned in the houses of the poor. The people thought, in 1824, that it was a substance unknown elsewhere, and they called it the "oil of Columbia." At that time they hoped to establish a valuable industry by working it, and they sent to England, France, and this country samples which attracted much attention. But in those days no method of refining the crude oil had been discovered, and therefore these efforts to introduce petroleum to the world soon failed.

The plains of Ceniza abound in asphalt and petroleum. There is a large lake of these substances about twelve kilometers east of St. Timoteo, and from it some asphalt is taken to Maracaibo. Many deposits of asphalt are found between these plains and the River Mene. The largest is that of Cienega de Mene, which is shallow. At the bottom lies a compact bed of asphalt, which is not used at present, except for painting the bottoms of vessels to keep off the barnacles. There are wells of petroleum in the State of Falcon.

Mr. Plumacher says that all the samples of coal submitted to him in Venezuela for examination, with the exception of the "lignite" before mentioned, were, in his opinion, asphalt in various degrees of condensation. The sample which came from Tule he ranks with the coals of the best quality. He believes that the innumerable fountains and deposits of petroleum, bitumen, and asphalt that are apparent on the surface of the region around Lake Maracaibo are proof of the existence below of immense deposits of coal. These deposits have not been uncovered because the territory remains for the most part as wild as it was at the conquest.

ONE THOUSAND HORSE-POWER CORLISS ENGINE.

FIG. 1.DIA. OF CYLINDER = 40''STROKE = 10 ft.REVS = 41SCALE OF DIAGRAMS 40 LBS = 1 INCHFIG. 2.

We illustrate one of the largest Corliss engines ever constructed. It is of the single cylinder, horizontal, condensing type, with one cylinder 40 inches diameter, and 10 feet stroke, and makes forty-five revolutions per minute, corresponding to a piston speed of 900 feet per minute. At mid stroke the velocity of the piston is 1,402 feet per minute nearly, and its energy in foot pounds amounts to about 8.6 times its weight. The cylinder is steam jacketed on the body and ends, and is fitted with Corliss valves and Inglis & Spencer's automatic Corliss valve expansion gear. Referring to the general drawing of the engine, it will be seen that the cylinder is bolted directly to the end of the massive cast iron frame, and the piston coupled direct to the crank by the steel piston rod and crosshead and the connecting rod. The connecting rod is 28 feet long center to center, and 12 inches diameter at the middle. The crankshaft is made of forged Bolton steel, and is 21 inches diameter at the part where the fly-wheel is carried. The fly driving wheel is 35 feet in diameter, and grooved for twenty-seven ropes, which transmit the power direct to the various line shafts in the mill. The rope grooves are made on Hick, Hargreaves & Co.'s standard pattern of deep groove, and the wheel, which is built up, is constructed on their improved plan with separate arms and boss, and twelve segments in the rim with joints planed to the true angle by a special machine designed and made by themselves. The weight of the fly-wheel is about 60 tons. The condensing apparatus is arranged below, so that there is complete drainage from the cylinder to the condenser. The air pump, which is 36 inches diameter and 2 feet 6 inches stroke, is a vertical pump worked by wrought iron plate levers and two side links, shown by dotted lines, from the main crosshead. The engine is fenced off by neat railing, and a platform with access from one side is fitted round the top of the cylinder for getting conveniently to the valve spindles and lubricators. The above engraving, which is a side elevation of the cylinder, shows the valve gear complete. There are two central disk plates worked by separate eccentrics, which give separate motion to the steam and exhaust valves. The eccentrics are mounted on a small cross shaft, which is driven by a line shaft and gear wheels. The piston rod passes out at the back end of the cylinder and is carried by a shoe slide and guide bar, as shown more fully in the detailed sectional elevation through the cylinder, showing also the covers and jackets in section. The cylinder, made in four pieces, is built up on Mr. W. Inglis's patent arrangement, with separate liner and steam jacket casing and separate end valve chambers. This arrangement simplifies the castings and secures good and sound ones. The liner has face joints, which are carefully scraped up to bed truly to the end valve chambers. The crosshead slides are each 3 feet 3 inches long and I foot 3 inches wide. The engine was started last year, and has worked beautifully from the first, without heating of bearings or trouble of any kind, and it gives most uniform and steady turning. It is worked now at forty-one revolutions per minute, or only 820 feet piston speed, but will be worked regularly at the intended 900 feet piston speed per minute when the spinning machinery is adapted for the increase which the four extra revolutions per minute of the engine will give; the load driven is over 1,000 horsepower, the steam pressure being 50 lb. to 55 lb., which, however, will be increased when the existing boilers, which are old, come to be replaced by new. Indicator diagrams from the engines are given on page 309. The engine is very economical in steam consumption, but no special trials or tests have been made with it. An exactly similar engine, but of smaller size, with a cylinder 30 inches diameter and 8 feet stroke, working at forty-five revolutions per minute, made by Messrs. Hick, Hargreaves & Co. for Sir Titus Salt, Sons & Co.'s mill at Saltaire, was tested about two years ago by Mr. Fletcher, chief engineer of the Manchester Steam Users' Association, and the results which are given below pretty fairly represent the results obtained from this class of engine. Messrs. Hick, Hargreaves & Co. are now constructing a single engine of the same type for 1,800 indicated horse-power for a cotton mill at Bolton; and they have an order for a pair of horizontal compound Corliss engines intended to indicate 3,000 horse-power. These engines will be the largest cotton mill engines in the world.--The Engineer.

1000 HORSE POWER CORLISS ENGINE.--BY HICK. HARGREAVES & CO.

Result of Trials with Saltaire Horizontal Engine on February 14th and 15th, 1878. Trials made by Mr. L.E. Fletcher, Chief Engineer Steam Users' Association, Manchester.

Engine single-cylinder, with Corliss valves. Inglis and Spencer's valve gear. Diameter of cylinder. 30in.; stroke, 8ft.; 45 revolutions per minute.

No. of trialsTotal 1.H.P.[MB] Mean boiler pressure.[MP] Mean pressure on piston at beginning of stroke.[ML] Mean loss between boiler pressure and cylinder.[MA] Mean average pressure on piston.[W]  Water Per I.H.P. per hour.[C]  Coal per I.H.P. per hour.No. of trials  Total  MB     MP     ML     MA     W      C               I.H.P. lb     lb     lb     lb     lb     lbTrial No. 1.  301.89  46.6   44.11   2.53  21.23  18.373  2.699Trial No. 2.  309.66  47.63  44.45   3.18  21.67  17.599  2.561Means.        305.775 47.115 44.28   2.855 21.45  17.986  2.630

1000 HORSE POWER CORLISS ENGINE.--BY HICK, HARGREAVES & CO.

1000 HORSE POWER CORLISS ENGINE.--BY HICK, HARGREAVES & CO.

OPENING OF THE NEW WORKSHOP OF THE STEVENS INSTITUTE OF TECHNOLOGY.

In our SUPPLEMENT No. 283 we gave reports of some of the addresses of the distinguished speakers, and we now present the remarks of Prof. Raymond and Horatio Allen, Esq.:

SPEECH OF PROF. R. W. RAYMOND.

A few years ago, at one of the meetings of our Society of Civil Engineers we spent a day or so in discussing the proper mode of educating young men so as to fit them for that profession. It is a question that is reopened for us as soon as we arrive at the age when we begin to consider what career to lay out for our sons. When we were young, the only question with parents in the better walks of life was, whether their sons should be lawyers, physicians, or ministers. Anything less than a professional career was looked upon as a loss of caste, a lowering in the social scale. These things have changed, now that we engineers are beginning to hold up our heads, as we have every reason to do; for the prosperity and well-being of the great nations of the world are attributable, perhaps, more to our efforts than to those of any other class. When, in the past, the man of letters, the poet, the orator, succeeded, by some fit expression, by some winged word, to engage the attention of the world concerning some subject he had at heart, the highest praise his fellow man could bestow was to cry out to him, "Well said, well said!" But now, when, by our achievements, commerce and industry are increased to gigantic proportions, when the remotest peoples are brought in ever closer communication with us, when the progress of the human race has become a mighty torrent, rushing onward with ever accelerating speed, we glory in the yet higher praise, "Well done, well done!" Under these circumstances, the question how a young man is best fitted for our profession has become one of increasing importance, and three methods have been proposed for its solution. Formerly the only point in debate was whether the candidate should go first to the schools and then to the workshop, or first to the shop and then to the schools. It was difficult to arrive at any decision; for of the many who had risen to eminence as engineers, some had adopted one order and some the other. There remained a third course, that of combining the school and the shop and of pursuing simultaneously the study of theory and the exercise of practical manipulation. Unforeseen difficulties arose, however, in the attempt to carry out this, the most promising method. The maintenance of the shop proved a heavy expense, which it was found could not be lessened by the manufacture of salable articles, because the work of students could not compete with that of expert mechanics. It would require more time than could be allotted, moreover, to convert students into skilled workmen. Various modifications of this combination of theory and practice, including more or less of the Russian system of instruction in shop-work, have been tried in different schools of engineering, but never under so favorable conditions as the present. With characteristic caution and good judgment, President Morton has studied the operation of the scheme of instruction adopted in the Stevens Institute, and, noting its deficiencies, has now supplied them with munificent liberality, giving to it a completeness that leaves seemingly nothing that could be improved upon, even in a prayer or a dream. Still, no one will be more ready to admit than he who has done all this, that it is not enough to fit up a machine shop, be it never so complete, and light it with an electric lamp. The decision as to its efficiency must come from the students that are so fortunate as to be admitted to it. If such young men, earnest, enthusiastic, with every incentive to exertion and every advantage for improvement, here, where they can feel the throbbing of the great heart of enterprise, within sight of bridges upon which their services will be needed, within hearing of the whistles of a score of railroads, and the bells of countless manufactories which will want them; if such as these, trained under such instructors and amid such surroundings, prove to be not fitted for the positions waiting for them to fill, it will have been definitely demonstrated that the perfect scheme is yet unknown.

SPEECH OF MR. HORATIO ALLEN.

Impressed with the very great step in advance which has been inaugurated here this evening, I feel crowding upon me so many thoughts that I cannot make sure that, in selecting from them, I may not leave unsaid much that I should say, and say some things that I had better omit. Some years ago, when asked by a wealthy gentleman to what machine-shop he had best send his son, who was to become a mechanical engineer, I advised him not to send him to any, but to fit up a shop for him where he could go and work at what he pleased without the drudgery of apprenticeship, to put him in the way of receiving such information as he needed, and especially to let him go where he could see things break. Great, indeed, are the advantages of those who have the opportunity of seeing things break, of witnessing failures and profiting by them. When men have enumerated the achievements of those most eminent in our profession the thought has often struck me, "Ah! if we could only see that man's scrap heap."

There are many who are able to construct a machine for a given purpose so that it will work, but to do this so that it will not cost too much is an entirely different problem. To know what to omit is a rare talent. I once found a young man who could tell students what to store up in their minds for immediate use, and what to skim over or omit; but I could not keep him long, for more lucrative positions are always waiting for such men.

The advice I gave my wealthy friend was given before the Stevens Institute had developed in the direction it has now. The foundation of this advice, namely, to combine a certain amount of judicious practice with theory, is now in a fair way to be carried out, and although things will probably not be permitted to break here, the students will doubtless have opportunities for looking around them and supplementing their systematic instruction here by observation abroad.

LIGHT STEAM ENGINE FOR BALLOONS.

We here illustrate one of a couple of compound engines designed and constructed by Messrs. Ahrbecker, Son & Hamkens, of Stamford Street, S.E., for Captain Mojaisky, of the Russian Imperial Navy, who intends to use them for aeronautical purposes. The larger of these engines has cylinders 3¾ in. and 7½ in. in diameter and 5 in. stroke, and when making 300 revolutions per minute it develops 20 actual horse power, while its weight is but 105 lbs. The smaller engine--the one illustrated--has cylinders 2½ in. and 5 in. in diameter, and 3½ in. stroke, and weighs 63 lbs., while when making 450 revolutions it develops 10 actual horse power.

The two engines are identical in design, and are constructed of forged steel with the exception of the bearings, connecting-rods, crossheads, slide valves and pumps, which are of phosphor-bronze. The cylinders, with the steam passages, etc., are shaped out of the solid. The standards, as will be seen, are of very light T steel, the crankshafts and pins are hollow, as are also the crosshead bolts and piston rods. The small engine drives a single-acting air pump of the ordinary type by a crank, not shown in the drawing. The condenser is formed of a series of hollow gratings.

LIGHT STEAM ENGINE FOR AERONAUTICAL PURPOSES

Steam is supplied to the two engines by one boiler of the Herreshoff steam generator type, with certain modifications, introduced by the designers, to insure the utmost certainty in working. It is of steel, the outside dimensions being 22 in. in diameter, 25 in. high, and weighs 142 lb. The fuel used is petroleum, and the working pressure 190 lb. per square inch.

The constructors consider the power developed by these engines very moderate, on account of the low piston speed specified in this particular case. In some small and light engines by the same makers the piston speed is as high as 1000 ft. per minute. The engines now illustrated form an interesting example of special designing, and Messrs. Ahrbecker, Son, and Hamkens deserve much credit for the manner in which the work has been turned out, the construction of such light engines involving many practical difficulties,--Engineering.

Mount Baker, Washington Territory, has shown slight symptoms of volcanic activity for several years. An unmistakable eruption is now in progress.

COMPLETE PREVENTION OF INCRUSTATION IN BOILERS.

The chemical factory, Eisenbuettel, near Braunschweig, distributes the following circular: "The principal generators of incrustation in boilers are gypsum and the so-called bicarbonates of calcium and magnesium. If these can be taken put of the water, before it enters the boiler, the formation of incrustation is made impossible; all disturbances and troubles, derived from these incrustations, are done away with, and besides this, a considerable saving of fuel is possible, as clear iron will conduct heat quicker than that which is covered with incrustation."

J. Kolb, according to Dingler's Polyt. Journal, says: "A boiler with clear sides yielded with 1 kil. coal 7.5 kil. steam, after two months only 6.4 kil. steam, or a decrease of 17 per cent. At the same time the boiler had suffered by continual working."

Suppose a boiler free from inside crust would yield a saving of only 5 per cent. in fuel (and this figure is taken very low compared with practical experiments) it would be at the same time a saving of 3c. per cubic meter water. If the cleaning of one cubic meter water therefore costs less than 3c., this alone would be an advantage.

Already, for a long time, efforts have been made to find some means for this purpose, and we have reached good results with lime and chloride of barium, as well as with magnesia preparations. But these preparations have many disadvantages. Corrosion of the boiler-iron and muriatic acid gas have been detected. (Accounts of the Magdeburg Association for boiler management.)

Chloride of calcium, which is formed by using chloride of barium, increases the boiling point considerably, and diminishes the elasticity of steam; while the sulphate of soda, resulting from the use of carbonate of soda, is completely ineffectual against the boiler iron. It increases the boiling point of water less than all other salts, and diminishes likewise the elasticity of steam (Wullner).

In using magnesia preparation, the precipitation is only very slowly and incompletely effected--one part of the magnesia will be covered by the mire and the formed carbonate of magnesia in such a way, that it can no more dissolve in water and have any effect (Dingler's Polyt. Journal, 1877-78).

The use of carbonate of soda is also cheaper than all other above mentioned substances.

One milligramme equivalent sulphate of lime, in 1 liter, = 68 grammes sulphate of lime in 1 cubic meter, requiring for decomposition:

120 gr. (86-88 per cent.) chloride of barium of commerce--at $5.00 = 0.6c.

Or, 50 gr. magnesia preparation--at $10.00 = 0.5c.

Or, 55 gr. (96-98 per cent.) carbonate of soda--at $7.50 = 0.41c.

The proportions of cost by using chloride of barium, magnesia preparation, carbonate of soda, will be 6 : 5 : 4.

ARRANGEMENT FOR PURIFYING BOILER-WATER WITH LIME AND CARBONATE OF SODA.

We need for carrying out these manipulations, according to the size of the establishment, one or more reservoirs for precipitating the impurities of the water, and one pure water reservoir, to take up the purified water; from the latter reservoir the boilers are fed. The most practical idea would be to arrange the precipitating reservoir in such manner that the purified water can flow directly into the feeding reservoir.

The water in the precipitating reservoir is heated either by adding boiling water or letting in steam up to 60° C. at least. The precipitating reservoirs (square iron vessels or horizontal cylinders--old boilers) of no more than 4 or 4½ feet, having a faucet 6 inches above the bottom, through which the purified water is drawn off, and another one at the bottom of the vessel, to let the precipitate off and allow of a perfect cleaning. In a factory with six or seven boilers of the usual size, making together 400 square meters heating surface, two precipitating reservoirs, of ten cubic meters each, and one pure water reservoir of ten or fifteen cubic meter capacity, are used.

In twenty-four hours about 240 cubic meters of water are evaporated; we have, therefore, to purify twenty-four precipitating reservoirs at ten cubic meters each day, or ten cubic meters each hour.

It is profitable to surround the reservoirs with inferior conductors of heat, to avoid losses.

The contents of the precipitating reservoirs have to be stirred up very well, and for this purpose we can either arrange a mechanical stirrer or do it by hand, or the best would be a "Korting steam stirring and blowing apparatus." In using the latter we only have to open the valve, whereby in a very short time the air driven through the water stirs this up and mixes it thoroughly with the precipitating ingredients. In a factory where boilers of only 15 to 100 square meters heating surface are, one precipitating reservoir of two to ten cubic meters and one pure water reservoir of three to ten cubic meters capacity are required. For locomobiles, two wooden tubs or barrels are sufficient.

THE PURIFICATION OF THE WATER.

After the required quantity of lime and carbonate of soda which is necessary for a total precipitation has been figured out from the analysis of the water, respectively verified by practical experiments in the laboratory, the heated water in the reservoir is mixed with the lime, in form of thin milk of lime, and stirred up; we have to add so much lime, that slightly reddened litmus paper gives, after ¼ minute's contact with this mixture, an alkaline reaction, i.e., turns blue; now the solution of carbonate of soda is added and again stirred well.

After twenty or thirty minutes (the hotter the water, the quicker the precipitation) the precipitate has settled in large flocks at the bottom, and the clear water is drawn off into the pure water reservoir. The precipitating and settling of the impurities can also take place in cold water; it will require, however, a pretty long time.

In order to avoid the weighing and slaking of the lime, which is necessary for each precipitation, we use an open barrel, in which a known quantity of slaked lime is mixed with three and a half or four times its weight of water, and then diluted to a thin paste, so that one kilogramme slaked lime is diluted to twenty-five liters milk of lime.

Example.--If we use for ten cubic meters water, one kilogramme lime, or in one day (in twenty-four hours), 240 cubic meters 24 kg. lime, a vessel four or five feet high and about 700 liters capacity, in which daily 24 kg. lime with about 100 liters water are slaked and then diluted to the mark 600, constantly stirring, 25 liters of this mixture contain exactly 1 kg. slaked lime.

Before using, this milk of lime has to be stirred up and allowed to settle for a few seconds; and then we draw off the required quantity of milk of lime (in our case 25 liters) through a faucet about 8 inches above the bottom, or we can dip it off with a pail. For the first precipitate we always need the exact amount of milk of lime, which we have figured out, or rather some more, but for the next precipitates we do not want the whole quantity, but always less, as that part of the lime, which does not settle with the precipitate, will be good for use in further precipitations. It is therefore important to control the addition of milk of lime by the use of litmus paper. If we do not add enough lime, it prevents the formation of the flocky precipitate, and, besides, more carbonate of soda is used. By adding too much lime, we also use more carbonate of soda in order to precipitate the excess of lime. We can therefore add so much lime, that there is only a very small excess of hydrous lime in the water, and that after well stirring, a red litmus paper being placed in the water for twenty seconds, appears only slightly blue. After a short time of practice, an attentive person can always get the exact amount of lime which ought to be added. On adding the milk of lime, we have to dissolve the required amount of pure carbonate of soda in an iron kettle, in about six or eight parts hot water with the assistance of steam; add this to the other liquid in the precipitating reservoirs and stir up well. The water will get clear after twenty-five or thirty minutes, and is then drawn off into the pure water reservoir.

EXAMINATION OF WATER WHICH HAS BEEN PURIFIED BY MEANS OF MILK OF LIME AND CARBONATE OF SODA.

In order to be convinced that the purification of the water has been properly conducted, we try the water in the following manner. Take a sample of the purified water into a small tumbler, and add a few drops of a solution of oxalate of ammonia; this addition must neither immediately nor after some minutes cause a milky appearance of the water, but remain bright and clear. A white precipitate would indicate that not enough carbonate of soda had been added. A new sample is taken of the purified water and a solution of chloride of calcium added; a milky appearance, especially after heating, would show that too much carbonate of soda had been added.

RESULTS OF THIS WATER PURIFICATION.

1. The boilers do not need to be cleaned during a whole season, as they remain entirely free from incrustation; it is only required to avoid a collection of soluble salts in the boiler, and therefore it is partly drawn off twice a week.

2. The iron is not touched by this purified water. The water does not froth and does not stop up valves. The fillings in the joints of pipes, etc., do not suffer so much, and therefore keep longer.

3. The steam is entirely free from sour gases.

4. The production of steam is easier and better.

5. A considerable saving of fuel can soon be perceived.

6. The cost of cleaning boilers from incrustation, and loss of time caused by cleaning, is entirely done with. Old incrustations, which could not be cleaned out before, get decomposed and break off in soft pieces.

7. The cost of this purification is covered sufficiently by the above advantages, and besides this, the method is cheaper and surer than any other.

The chemical factory, Eisenbuettel, furnishes pure carbonate of soda in single packages, which exactly correspond with the quantity, stated by the analysis, of ten cubic meters of a certain water. The determination of the quantities of lime and carbonate of soda necessary for a certain kind of water, after sending in a sample, will be done without extra charge.--Neue Zeitung fur Ruebenzucker Industrie.

EDDYSTONE LIGHTHOUSE.

The exterior work on the new Eddystone Lighthouse is about two thirds done. In the latter part of April fifty-three courses of granite masonry, rising to the height of seventy feet above high water, had been laid, and thirty-six courses remained to be set. The old lighthouse had been already overtopped. As the work advances toward completion the question arises: What shall be done with John Smeaton's famous tower, which has done such admirable service for 120 years? One proposition is to take it down to the level of the top of the solid portion, and leave the rest as a perpetual memorial of the great work which Smeaton accomplished in the face of obstacles vastly greater than those which confront the modern architect. The London News says: "Were Smeaton's beautiful tower to be literally consigned to the waves, we should regard the act as a national calamity, not to say scandal; and, if public funds are not available for its conservation, we trust that private zeal and munificence may be relied on to save from destruction so interesting a relic. It certainly could not cost much to convey the building in sections to the mainland, and there, on some suitable spot, to re-erect it as a national tribute to the genius of its great architect." When the present lighthouse was built one of the chief difficulties was in getting the building materials to the spot. They were conveyed from Millbay in small sailing vessels, which often beat about for days before they could effect a landing at the Eddystone rocks, so that each arrival called out the special gratitude of Smeaton.

ROLLING-MILL FOR MAKING CORRUGATED IRON.

MESSRS. SCHULZ, KNAUDT & Co., of Essen, who are making an application of corrugated iron in the construction of the interior flues of steam boilers, have devised a new mill for the manufacture of this form of iron plates, and which is represented in the accompanying cut, taken from the Deutsche Industrie Zeitung. The supports of the two accessory cylinders, F F, rest on two slides, G G, which move along the oblique guides, H H. As a consequence of this arrangement, when the cylinders, F F, are caused to approach the cylinder, D, both are raised at the same instant.

When the cylinders, F, occupy the position represented in the engraving by unbroken lines, the flat plate, O, is simply submitted to pressure between the cylinders, D and P, the cylinders, F F, then merely acting as guides. But when, while the plate is being thus flattened between the principal cylinders, the accessory cylinders are caused to rise, the plate is curved as shown by the dotted lines, O' O'. To obtain a uniformity in the position of the two cylinders, F F, the following mechanism is employed: Each cylinder has an axle, to which is affixed a crank, Q, connected by means of a rod, R, with the slide, G. These axles are also provided with toothed sectors, L L, which gear with two screws, L L, whose threads run in opposite directions. These screws are mounted on a shaft, N, which may be revolved by any suitable arrangement.

ROLLING MILL FOR MAKING CORRUGATED IRON

RAILWAY TURN-TABLE IN THE TIME OF LOUIS XIV.

The small engraving which we reproduce herewith from La Nature is deposited at the Archives at Paris. It is catalogued in the documents relating to Old Marly, 1714, under number 11,339, Vol. 1. The design represents a diversion called the Jeu de la Roulette which was indulged in by the royal family at the sumptuous and magnificent chateau of Mary-le-Roi.

PLEASURE CAR; RAILWAY AND TURN-TABLE OF THE TIME OF LOUIS XIV.

According to Alex. Guillaumot the apparatus consisted of a sort of railway on which the car was moved by manual labor. In the car, which was decorated with the royal colors, are seen seated the ladies and children of the king's household, while the king himself stands in the rear and seems to be directing operations. The remarkable peculiarity to which we would direct the attention of the reader is that this document shows that the car ran on rails very nearly like those used on the railways of the present time, and that a turn-table served for changing the direction to a right angle in order to place the car under the shelter of a small building. The picture which we reproduce, and the authenticity of which is certain, proves then that in the time of Louis XIV. our present railway turn-tables had been thought of and constructed--which is a historic fact worthy of being noted. It is well known that the use of railways in mines is of very ancient date, but we do not believe that there are on record any documents as precise as that of the Jeu de la Roulette as to the existence of turn-tables in former ages.

NEW SIGNAL WIRE COMPENSATOR.

To the Editor of the Scientific American:

I send you a plate of my new railway signal wire compensator. Here in India signal wires give more trouble, perhaps, than in America or elsewhere, by expansion and contraction. What makes the difficulty more here is the ignorance and indolence of the point and signalmen, who are all natives. There have been numerous collisions, owing to signals falling off by contraction. Many devices and systems have been tried, but none have given the desired result. You will observe the signal wire marked D is entirely separated and independent of the wire, E, leading to lever. On the Great Indian and Peninsula Railway I work one of these compensators, 1,160 yards from signal, which stands on a summit the grade of which is 1 in 150; and on the Nizam State Railway I have one working on a signal 800 yards. This signal had previously given so much trouble that it was decided to do away with it altogether. It stands on top of a high cutting and on a 1,600 foot curve.

Railway Signal Wire Comensator

I have noted on the compensator fixed at 1,160 yards, 13¼ inches contraction and expansion. The compensator is very simple and not at all likely to get out of order. On new wire, when I fix my compensator, I usually have an adjusting screw on the lead to lever. This I remove when the wire has been stretched to its full tension. I have everything removed from lever, so there can be no meddling or altering. When once the wire is stretched so that no slack remains between lever and trigger, no further adjustment is necessary.

A. LYLE,

Chief Maintenance Inspector, Permanent Way,

H.H. Nizam State Railway, E. India.

Secunderabad, India, 1881.

TANGYE'S HYDRAULIC HOIST.

TANGYE'S HYDRAULIC HOIST.

The great merits of hydraulic hoists generally as regards safety and readiness of control are too well known to need pointing out here. We may, therefore, at once proceed to introduce to our readers the apparatus of this class illustrated in the above engravings. This is a hoist (Cherry's patent) manufactured by Messrs. Tangye Brothers, of London and Birmingham, and which experience has proved to be a most useful adjunct in warehouses, railway stations, hotels, and the like. Fig. 1 of our engraving shows a perspective view of the hoist, Fig. 2 being a longitudinal section. It will be seen that this apparatus is of very simple construction, the motion of the piston being transmitted directly to the winding-drum shaft by means of a flexible steel rack. Referring to Fig. 2, F is a piston working in the cylinder, G; E is the flexible steel rack connected to the piston, F, and gearing with a toothed wheel, B, which is inclosed in a watertight casing having cover, D, for convenient access. The wheel, B, is keyed on a steel shaft, C, which passes through stuffing-boxes in the casing, and has the winding barrel, A, keyed on it outside the casing. H is a rectangular tube, which guides the free end of the flexible steel rack, E. The hoist is fitted with a stopping and starting valve, by means of which water under pressure from any convenient source of supply may be admitted or exhausted from the cylinder. The action in lifting is as follows: The water pressure forces the piston toward the end of the cylinder. The piston, by means of the flexible steel rack, causes the toothed wheel to revolve. The winding barrel, being keyed on the same shaft as the toothed wheel, also revolves, and winds up the weight by means of the lifting chain. Two special advantages are obtained by this simple method of construction. In the first place, twice the length of stroke can be obtained in the same space as compared with the older types of hydraulic hoist; and, from the directness of the action, the friction is reduced to a minimum. This simple method of construction renders the hoist very compact and easily fixed; and, from the directness with which the power is conveyed from the piston to the winding drum, and the frictionless nature of the mechanism, a smaller piston suffices than in the ordinary hydraulic hoists, and a smaller quantity of water is required to work them.--Iron.

POWER LOOM FOR DELICATE FABRICS.

The force with which the shuttle is thrown in an ordinary power loom moving with a certain speed is always considerable, and, as a consequence of the strain exerted on the thread, it is frequently necessary to use a woof stronger than is desirable, in order that it may have sufficient resistance. On another hand, when the woof must be very fine and delicate the fabric is often advantageously woven on a hand loom. In order to facilitate the manufacture of like tissues on the power loom the celebrated Swiss manufacturer, Hanneger, has invented an apparatus in which the shuttle is not thrown, but passed from one side to the other by means of hooks, by a process analogous to weaving silk by hand. A loom built on this principle was shown at work weaving silk at the Paris Exhibition of 1878. This apparatus, represented in the annexed figure, contains some arrangements which are new and interesting. On each side of the woof in the heddle there is a carrier, B. These carriers are provided with hooks, A A', having appendages, a a', which are fitted in the shuttle, O. The latter is of peculiar construction. The upper ends of the hooks have fingers, d d', which holds the shuttle in position as long as the action of the springs, e e', continues. The distance that the shuttle has to travel includes the breadth of the heddle, the length of the shuttle, and about four inches in addition. The motion of the two carriers, which approach each other and recede simultaneously, is effected by the levers, C, D, E, and C', D', E'. The levers, E, E', are actuated by a piece, F, which receives its motion from the main shaft, H, through the intervention of a crank and a connecting rod, G, and makes a little more than a quarter revolution. The levers, E, E', are articulated in such a way that the motion transmitted by them is slackened toward the outer end and quickened toward the middle of the loom. While the carriers, B B', are receiving their alternate backward and forward motion, the shaft, I (which revolves only half as fast as the main shaft), causes a lever, F F', to swing, through the aid of a crank, J, and rod, K. Upon the two carriers, B B', are firmly attached two hooks, M M', which move with them. When the hook, M, approaches the extremity of the lever, F, the latter raises it, pushes against the spring, E, and sets free the shuttle, which, at the same moment, meets the opposite hook, a', and, being caught by it, is carried over to the other side. The same thing happens when the carrier, B', is on its return travel, and the hook, M', mounts the lever, F', which is then raised.

POWER LOOM FOR DELICATE FABRICS.

As will be seen from this description, the woof does not undergo the least strain, and may be drawn very gently from the shuttle. Neither does this latter exert any friction on the chain, since it does not move on it as in ordinary looms. In this apparatus, therefore, there may be employed for the chain very delicate threads, which, in other looms, would be injured by the shuttle passing over them. Looms constructed on this plan have for some time been in very successful use in Switzerland.

HOW VENEERING IS MADE.

The process of manufacture is very interesting. The logs are delivered in the mill yard in any suitable lengths as for ordinary lumber. A steam drag saw cuts them into such lengths as may be required by the order in hand; those being cut at the time of our visit were four feet long. After cutting, the logs are placed in a large steam box, 15 feet wide, 22 feet long, and six feet high, built separate from the main building. This box is divided into two compartments. When one is filled entirely full, the doors are closed, and the steam, supplied by the engine in the main building, is turned on. The logs remain in this box from three to four hours, when they are ready for use. This steaming not only removes the bark, but moistens and softens the entire log. From the steam box the log goes to the veneer lathe. It is here raised, grasped at each end by the lathe centers, and firmly held in position, beginning to slowly revolve. Every turn brings it in contact with the knife, which is gauged to a required thickness. As the log revolves the inequalities of its surface of course first come in contact with the keen-edged knife, and disappear in the shape of waste veneer, which is passed to the engine room to be used as fuel. Soon, however, the unevenness of the log disappears, and the now perfect veneer comes from beneath the knife in a continuous sheet, and is received and passed on to the cutting table. This continues until the log is reduced to about a seven inch core, which is useless for the purpose. The veneer as it comes rolling off the log presents all the diversity of colors and the beautiful grain and rich marking that have perhaps for centuries been growing to perfection in the silent depths of our great forests.

From the lathe, the veneer is passed to the cutting table, where it is cut to lengths and widths as desired. It is then conveyed to the second story, where it is placed in large dry rooms, air tight, except as the air reaches them through the proper channels. The veneer is here placed in crates, each piece separate and standing on edge. The hot air is then turned on. This comes from the sheet iron furnace attached to the boiler in the engine room below, and is conveyed through large pipes regulated by dampers for putting on or taking off the heat. There is also a blower attached which keeps the hot air in the dry rooms in constant motion, the air as it cools passing off through an escape pipe in the roof, while the freshly heated air takes its place from below. These rooms are also provided with a net-work of hot air pipes near the floor. The temperature is kept at about 165°, and so rapid is the drying process that in the short space of four hours the green log from the steam box is shaved, cut, dried, packed, and ready for shipment.

After leaving the dry rooms it is assorted, counted, and put up in packages of one hundred each, and tied with cords like lath, when it is ready for shipment. Bird's-eye maple veneer is much more valuable and requires more care than almost any other, and this is packed in cases instead of tied in bundles. The drying process is usually a slow one, and conducted in open sheds simply exposed to the air. Mr. Densmore's invention will revolutionize this process, and already gives his mill a most decided advantage.

The mill will cut about 30,000 feet of veneer in a day, and this cut can be increased to 40,000 if necessary. Mr. Densmore has already received several large orders, and the rapidly increasing demand for this material is likely to give the mill all the work it can do. The timber used is principally curled and bird's-eye maple, beech, birch, cherry, ash, and oak. These all grow in abundance in this vicinity, and the beautifully marked and grained timber of our forests will find fitting places in the ornamental uses these veneers will be put to.

THE CONSTITUENT PARTS OF LEATHER.

The constituent parts of leather seem to be but little understood. The opinions of those engaged in the manufacture of leather differ widely on this question.

Some think that tannin assimilates itself with the hide and becomes fixed there by reason of a special affinity. Others regard the hide as a chemical combination of gelatine and tannin. We know that the hide contains some matters which are not ineradicable, but only need a slight washing to detach them.

We deem it advisable, in order to examine the hide properly so-called, to dispense with those eradicable substances which may be regarded, to some extent, as not germain to it, and confine our attention to the raw stock, freed from these imperfections.

It is well known that a large number of vegetable substances are employed as tanning agents. Our researches have been directed to leather tanned by means of the most important of these agents.

Many questions present themselves in the course of such an examination. Among others, that most important one, from a practical point of view, of the weight the tanning agent gives to the hide, that is to say, the result in leather of weight given to the raw material. The degree of tannage is also to be considered; the length of time during which the tanning agent is to be left with the hide; in short, the influence upon the leather of the substances used in its production. That is why we have made the completest possible analysis of different leathers.

Besides ordinary oak bark there are used at present very different substances, such as laurel, chestnut, hemlock, quebracho and pine bark, sumac, etc.

Water is an element that exists in all hides, and it is necessary to take it into consideration in the analysis. It is present in perceptible quantity even in dry hides. This water cannot be entirely eradicated without injuring the leather, which will lose in suppleness and appearance. Water should then be considered as one of the elements of leather, but it must be understood that if it exceeds certain limits, say 12 to 14 per cent., it becomes useless and even injurious. Moreover, if there is any excess over the normal quantity, it becomes deceptive and dishonest, as in such a case one sells for hides that which is nothing but water. Supposing that a hide, instead of only 14 per cent., contained 18 per cent. of water, it is evident that in buying 100 pounds of such a hide one would pay for four pounds of water at the rate for which he purchased the hide.

There are, also, some matters soluble in air, which are formed to a large extent from fat arising as much from the hide as from tanning substances. The air dissolves at the same time a certain amount of organic acid and resinous products which the hide has absorbed. After treating with air, alcohol is used, which dissolves principally the coloring matters, tannin which has not become assimilated, bodies analogous to resin, and some extractive substances.

That which remains after these methods have been pursued ought to be regarded as the hide proper, that is to say, as the animal tissue saturated with tannic acid. In this remainder one is able to estimate with close precision that which belongs to the hide. The hide being an elementary tissue of unchangeable form, it is easy, in determining the elementary portion, to find the amount of real hide remaining in the product. With these elements one can arrive at a solution of some of the questions we are discussing.

We give below, according to this method, a table showing the composition of the different leathers exhibited at the Paris Exposition of 1878. They are the results of careful research, and we have based our work upon them:

                                                  Matter Soluble      Fixed                                                      in Air         Tannin                                                      |                 |                                                      | Matter Solu-    |                                                      | ble in Alcohol  |                                                      |     |           |                                           Moisture   |     | Gelatine  |                                             --+--  --+-- --+-- --+-- --+--Steer hide, hemlock tanned (heavy leather)   10.95   4.15 19.77 39.1  26.03Sheepskins, sumac     "    (Hungarian)       10.8   10.3  12.1  40.3  26.5Finished calf, pine bark tanned (Hungarian)  11.2    1.7   7.4  41.6  38.1Steer hide, quebracho tanned (heavy leather) 11.7    1.6  11.2  43.1  32.4  "    "    chestnut    "       "      "     13.5    0.29  1.99 45.46 38.76Finished calfskins,               oak tanned (Chateau Renault)  12.4    0.33  3.59 46.74 36.94Steer hide, laurel tanned (heavy leather)    12.4    1.05  7.95 47.47 31.13  "    "    oak tanned after three years in        the vats (heavy leather)             11.45   0.37  3.31 49.85 35.02

The following table shows the amount of leather produced by different tannages of 100 pounds of hides:

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