strengths of current employed. Since, however, the increase of magnetism from the second last to the last observation, in cobalt, was much greater than in nickel, it is not impossible that, with very strong electric currents, the magnetism of cobalt may be greater than that of nickel. Unlike the nickel, the cobalt piece was not without coercive force.

New Electro-Motor. In a new electromotor recently exhibited in London by its inventor, Chutaux, the primary force is supplied by a battery of eight or more cells, being a modification of the Bunsen battery. The elements used are graphite and unamalgamated zinc, and the exciting fluids are sulphuric acid and bichromate of potash in the inner (or graphite) cell, and a solution of acid sulphate or bisulphate of potash in the outer (zinc) cell. No material action is exerted on the zinc while the battery is at rest, hence the reason for dispensing with the process of amalgamation. Two or more horseshoe electroinagnets, with their poles upward, are worked by the current, a wheel rotating on an horizontal axis immediately above and almost touching them. This wheel is practically formed of two parallel wheels joined at their circumference by a series of soft-iron bars. As soon as the current is set up the wheel begins to revolve, owing to the attraction between the electro-magnets and the iron, the motion being kept up, and rapidly increased, by means of a simple automatic "current-reverser." The principal feature to which the inventor draws attention is the construction of the transverse soft-iron bars, each of which is composed of seven thin plates, much being thus gained in intensity of magnetization, and consequently in mechanical power. By a series of ingenious devices the machine is applied to the working of pumps, sewing-machines, lathes, etc., as a substitute for manual or foot labor. It is not of course in any way intended to supersede steam, its object being the simple and easy performance of labor of a light description. The battery is free from smell, and, being very “constant,” will last for a long time without renewal, the trouble involved in starting and stopping the machine being practically nil.

Influence of the Electric Current on the Dimensions of Iron.-The change in length of a conductor, through which an electric current is passing, has been measured by Exner, whose method is free from the error caused by the expansion due to the heat produced by the current. In making this measurement, two pieces of the same wire of nearly equal lengths were hung one over the other, and so connected with a battery that the current might be passed through either. The lower wire was passed through a glass which might be filled with water if desired. The elongation was measured by resting the end of the wire on a lever carrying a mirror whose deflection was read by a microscope and scale. The current being passed successively through the two

wires, a different deflection was obtained in each case, but these were rendered equal by inserting an additional resistance in circuit with that wire whose elongation was greater. The tube was now filled with water so as to carry off the heat generated in the lower wire as rapidly as possible. It was found that the galvanic expansion was only 1.2 to 2.2 per cent. of the heat-expansion; and no connection was recognizable with the nature of the metal employed. If it be considered that these values, of course, can only be an upper limit, it will follow, from the smallness of the effect obtained, that there is no sufficient ground for the hypothesis of a special expansion power of the galvanic current. There can hardly be any doubt that the slight expansion which the water-inclosed wire still shows is simply and alone due to the heat remaining in it.

Magnetic Equivalent of Heat.-In Lamin and Roger's decisive experiment establishing the production of heat through disappearance of magnetism, the soft iron of an electro-magnet was placed in the reservoir of a large thermometer of oil of turpentine; on sending an interrupted current through the spiral, it was observed that the liquid expanded. The conclusion hence drawn was, that during each magnetization a part of the electricity goes into the iron, producing magnetism, and that at the moment of demagnetization this magnetism is transformed into heat. In further investigating this subject, Cazin employed three different methods of experimentation. In the first, the iron core was inclosed in an hermetically-closed vessel filled with petroleum, and surrounded by the magnetizing spiral. From the vessel proceeded a capillary tube, also containing petroleum, and the changes of level in it were observed when the core was magnetized by an interrupted current. But inasmuch as change of level might arise, not from heat-action, but from the expansion of the iron by magnetism, the following experiment was arranged:

Into the vessel containing the liquid and the iron core were introduced some closed glass tubes, which displaced a third of the liquid; the vessel was then closed, and the experiment repeated. If the expansion of the iron were the cause of the change of level, this must now be the same as in the experiment without the glass tubes; if, on the other hand, the change of the level were due to the heat produced, it must now be different, for, instead of three volumes glass were heated by the same quantity of heat. of liquid, two volumes of liquid and one volume of The experiment then revealed a difference, which corresponded to the difference of the specific heats and confinements of expansion of petroleum-oil and glass.

It was thus proved that the discontinuous magnetization of an iron core produces heat. In another method for demonstrating and measuring this heat-effect, the core was an iron tube, closed at both ends with corks, and inclosing the bulb of a common thermometer. Here, again, there was heat-action when the spiral was traversed by an interrupted cur

rent. In the third method a differential thermometer was used, consisting of two hollow iron cores, communicating by a capillary tube in which was a liquid index: every heat-action in the one core was followed by an expansion of the contained air, and displacement of the index.

In order to determine the cause of the development of heat, M. Cazin proceeded as follows:

Round the iron core in the petroleum thermometer two coils of 480 turns were passed, one of them being in the interrupted magnetizing circuit, while the other formed a special circuit, which at each turn of the interrupting apparatus was closed. The first coil could now induce a current in the second, if the closures of the two circuits took place at the proper times, as might be arranged at will. These experiments gave the greatest development of heat when the circuit of the second spiral remained continually open. The heat was not altered when the circuit was closed at closing of the magnetizing current. There is thus no thermal action during the variable period of closure. Lastly, the heat was smaller when the circuit of the second spiral, during the opening of the inducing circuit, was closed; it went down as much as the half. "It thus proved that the production of the magnetic heat takes place during the opening of the voltaic circuit; consequently, that it accompanies the disappearance of magnetism in the core."

The decrease of heat in this last case is explained on the principle of thermo-dynamics. The disappearance of the magnetism is the cause of the appearance of a certain quantity of heat. When no circuit is near, in which an induced current can arise, then the whole of this heat appears in the core; but, when induction occurs, a part of the heat appears in the induced circuit, and the rest remains in the core. The cessation of the magnetization is an operation in which the magnetic energy decreases and is transformed into heat-energy, either in the core or in the neighboring masses which are in a position to be the seat of induction phenomena.

Improved Electric Railway-Signal.-A simple and effective application of electricity to railroad signaling is in use on the Boston, Lowell & Nashua Railroad. The apparatus is described and illustrated with a woodcut in the Scientific American. Its principle will be readily understood from what follows: A single-cell Callaud battery is connected to the two rails at one end of a given section of the line (say two miles in length), each section being insulated from adjoining sections. At the other end of the section the signal has an electromagnet similarly connected to the two rails. When the circuit is closed, as is normally the case, the magnet is excited and the signal controlled thereby, so as to show that the line is clear. But when a train enters on the section, then a shorter circuit is made by the wheels and axles, and the current returns to the battery by this course instead of passing through the signals. The magnet ceases now to attract, and the signal, by mechanical means, is at once turned to indicate danger. It is ob

vious that this must occur as long as a single car remains on the track, or when the circuit is broken by a displaced or broken rail, or any other cause. Hence the device may be applied over an entire line, and will indicate the condition of every section to a train about to enter on the same. It is not affected by changes of weather.

ELIO, JOAQUIN, a Spanish general, died in January, 1876, very much advanced in years. He was educated for service in the royalist army in Spain, in which he obtained his first commission. During the progress of a stormy public career, he served under many governments. In 1860 he commanded a part of the Carlist insurgents, and during the last Carlist War he also acted with Don Carlos, by whom he had been threatened with the loss of his command, and with court-martial, on several occasions. In 1860 he was captured by Queen Isabella's forces, and was only saved from death by the clemency of the Queen. On that occasion, he wrote a letter to the Queen, in which he promised never again to take part in any movements against her; but, nevertheless, he fought in the Carlist War against her son, Don Alfonso. Don Carlos appointed him in 1873 captain-general of the Carlist forces, and Minister of War. He conducted the operations of the Carlist forces against Bilbao, and the defense of the line of Sommorastra, in 1874, and, when the Carlists were repulsed there, he resigned his position, but remained with the army.

ENGINEERING. The art of engineering has made great strides in late times, and, with the growth of commerce, has been put more and more into requisition to devise and construct shorter and easier avenues of communication. In all progressive countries gigantic works are constantly in progress, requiring millions of outlay and years of labor, while still greater undertakings are being seriously proposed, such as would formerly have been considered fond and idle dreams. Among them may be mentioned the connection of the Black Sea with the Caspian by a ship-canal; the construction of an artificial channel between the great rivers of Central Africa, so as to make a navigable water-way across the continent; the cutting of a passage between the sea and the low bed of the great African Desert, by which a great portion of the sandy waste would be submerged, and wide districts rendered fertile; the building of a great shipcanal through Southern France from the bay of Biscay to the Mediterranean; the widening and deepening of the Seine, so as to make Paris a seaport.

It is worthy of note that the chief engineering projects of the most recent times look toward the extension and improvement of water-communication. The construction of a ship-canal through the American Isthmus, which has long been a cherished project of the American people, may be said to be on the

way to be realized. The commission appointed by the United States Government to consider its feasibility, and select the best route, have presented a final report; and treaties are in progress with other countries concerning it. The Dutch have achieved a great engineering success in the completion of the North Sea Canal, which makes a seaport of the city of Amsterdam, floating the largest vessels, and allowing direct steamboat communication with foreign ports. The St. Gothard Tunnel is approaching completion; but its undertakers have been greatly dismayed by the discovery of an enormous miscalculation in the estimates of cost. Extensive and costly experiments upon the proposed railway-tunnel through the chalk-beds underlying the straits of Dover are undertaken, and will amount to a commencement of the work, if it shall be found feasible. In Italy we see the completion of an enterprise which has been pursued for many years, by which a large tract of land, submerged for ages, has been recovered to agriculture. Other similar works are proposed for the reclamation of the wide ranges of land which lie waste in that country, covered with disease-generating marshes; while in Holland a plan is seriously entertained by the Government for the draining and fertilization of the bed of the Zuyder Zee, which would increase the territory of that country about one-sixth, and afford a permanent revenue of millions of francs to the Government. The long-expected Russian railway across Central Asia has not yet been practically commenced, though the project is gaining favor. In our own country, the great works of river and harbor improvement, which have been carried on by the Government, are still under vigorous prosecution; the chief results of this year's labors have been the clearing away of Hallett's Reef, one of the most serious obstructions in the East River channel (see article HELL-GATE), and the deepening of the chief outlet of the Mississippi (see below).

The survey which has been conducted by the commission of the American Government for five years past upon the isthmuses of Panama and Nicaragua, with reference to a ship-canal, has been completed within the year, and final reports have been presented to the President. The route which was found most promising and practicable was one across the Nicaraguan Isthmus, by way of Lake Nicaragua. Four other proposed routes have been carefully examined. The one across the isthmus of Panama, formerly much thought of, was found to present the greatest difficulties. J. C. Trautwine, chiefengineer of the Panama Railroad, lately expressed an opinion that a canal over that route would cost not less than $300,000,000! The survey across the isthmus of Tehuantepec, under Commodore Shufeldt and Engineer Fuertes, showed that the line proposed by those engineers by way of the river Coatzacoalcos would require the construction of as many as 140 locks, which, in connection with

the deficient water-supply, was enough to condemn the plan. The route between the gulf of San Blas and the river Chepo or Bayanos has been supposed to be a specially desirable one, because the tides from both oceans are nearer together at this point than elsewhere; but the survey revealed insurmountable difficulties, even after an eight-mile tunnel should have been cut. A survey from Caledonia Bay out discovered no pass at a less elevation than 1,000 feet. Several other routes which were surveyed showed difficulties still more formidable. The Government has expended about $60,000 in this investigation.

The treaties with foreign powers are to be made on the basis of the Clayton-Bulwer Treaty of 1850, guaranteeing the neutrality of the canal. The estimate of the cost returned by the commission is $65,722,157; but several practical engineers, who have examined the route, conjecture that obstacles will be encountered which will increase the cost to nearly $100,000,000. The work cannot be completed in less than five years of hard labor; but if it is sustained by the leading governments, it is supposed that it will not be delayed or abandoned for want of funds. The distance to be excavated is 614 miles, and the total length of the canal, including 53 miles of slackwater navigation, by way of the San Juan River, and 56 miles across Lake Nicaragua, will be 180 miles from ocean to ocean. a number of years there has been a considerable and increasing transportation traffic by the way of Lake Nicaragua and the San Juan River. Whether a ship-canal across the Nicaraguan Isthmus would draw any of Europe's trade with the East from the Suez Canal is doubtful; but the benefits it would afford to the American trade with the East and the Pacific coast, and the improved communication it would render between the western side of the North and South American Continents, and the whole commercial world, would be much more than commensurate with its cost.

For

An American engineer, Henry C. Spalding, has broached a scheme for letting the waters of the Black Sea into the Caspian through an artificial channel-way, thus greatly enlarging the area of the latter sea by the submersion of comparatively sterile tracks, but immensely improving the fertility of the surrounding regions, and giving Russia maritime communication with the commercial world, and a broad sea-coast. His project is to cut a canal, 150 metres wide, from a point in the basin of the Caspian Sea, which is 15 metres below the level of the Black Sea, in a westerly direction to such a point that it will have a depth of 10 metres; from there a narrower cutting is to be carried on to the Black Sea. This narrower channel, he calculates, should have a depth of three metres where it strikes the Black Sea, and a width of 50 metres; through this the water would flow with a velocity of 12 kilometres an hour, and, where it gives into the larger

timated at 34 metres. If 9,400-horse power is applied it is calculated that the lake will be drained in about two years, at the rate of 4,500 cubic metres per minute. The only efficient power here applicable is supposed to be the steam-engine. After the steam-pumps have done their business, dredges will have to be employed to dig out the bottoms of the canals, and clear away the mud, where large structures have to be built. For the foundation of many of the heavy structures it will be necessary to sink piles and bundles of fascines, as has been done in the making of the great Amsterdam Canal. The entire work, it is estimated, can be completed in from twelve to sixteen years. The surface drained will be 196,670 hectares, or about 795 square miles, of which area about one-tenth will be taken up by roads and canals. It is supposed that, with all allowances, there will be about 150,000 hectares of fine, tillable land. The expense of the undertaking is estimated at 240,000,000 francs, a large estimate, exclusive of interest. If the Government should carry out the undertaking, as seems most likely, it is calculated that it would bring in, after completion, an annual revenue of 1,880,000 francs.

Two enterprises for the reclamation of large submerged tracts are successfully in progress in Italy. The Ferrara Marshes, in Northern Italy, are being drained by means of steampumps, constructed by John and Henry Gwynne, of Hammersmith, England. The area to be reclaimed is 200 square miles. The engines lift 2,000 tons of water per minute through an average distance of seven feet three inches. The maximum lift is twelve feet. The water is discharged into the river Volano, at Cordigoro. Another large enterprise is the drainage of Lake Fucino, which lies about 55 miles east of Rome, and has an area of sixty-one square miles, by means of a siphon 1,500 yards long, from canals which have been dredged out at the bottom. The works have been going on many years, at the expense of the late Prince Torlonia, and the enterprise will soon become remunerative. This area was drained by the Emperor Claudius, and the ancient works were suffered to go to decay in the middle ages. The project was at first designed to restore the Roman works, and a company was formed in 1855 for that purpose, and the work was intrusted to M. de Montricher, a well-known French engineer. This was found impracticable, and, the Prince Torlonia assuming the entire responsibility, the present works were constructed. About 50,000,000 francs have been expended upon them thus far.

There are suggestions of extensive improvements in the harbor of Genoa, and various plans have been proposed for the work. It has long been the dream of the Genoese to make their harbor the best in the Mediterranean, and regain their ancient commerce and prestige on the seas. A nobleman of Genoese birth, it is said, has presented the city with the sum of

20,000,000 francs, to be devoted to harbor improvements.

The tunnel under the English Channel, for the commencement of which companies have been formed in London and Paris, it is proposed to construct on the route proposed by Sir John Hawkshaw, from St. Margaret's Bay to a point near Sangatte on the French coast. In this course it is expected that it will pass through chalk-beds the entire way, while in the route proposed by M. Thomé de Gamond it is known that several different strata would be encountered. The distance across the Channel in the proposed course is 22 miles, which, with the long approaches necessary, would make 31 miles altogether. Shafts are to be sunk on either shore to the depth of 450 feet below high-water mark. At that depth driftways are to be driven, which will serve for the drainage of the works when in progress, and of the tunnel permanently. The tunnel will commence 200 feet above the driftway, with an inclination of one foot in eighty down to the junction with the driftway, and then of one foot in 2,640 to the centre of the Channel, where it will meet that driven from the other side. The dimensions of the tunnel will be those of an ordinary railroad-tunnel for two tracks. A driftway, nine feet in diameter, it is proposed first to carry entirely through, which can afterward be enlarged to the size of the tunnel. A machine for tunneling in chalk has been invented by Dickenson Brunton, an English engineer, which has been successfully tried upon the bed of gray chalk through which the tunnel is to be made. It works similarly to an ordinary board-auger, cutting off the chalk in slices, which fall upon an endless band, and are loaded upon wagons. The machine, it is found, can cut a driftway of seven feet diameter at the rate of something over a yard an hour. At that rate it would take two years to complete a driftway under the Channel with a machine starting from each side. The expense of completing such a driftway is estimated at £800,000, including interest upon the outlay. Engineers and contractors of experience have calculated that, after the driftway should be completed, it would take four years' time and £4,000,000 only to enlarge it to the dimensions of a raiload-tunnel, and to construct the junctions with the railways on either side. It seems certain now that the commencement of this work will soon be made and its practicability tested. The companies which have been formed for this purpose are to unite with the French and English railways interested, and with the Rothschilds of London and Paris, in making up the sum of £160,000, to be expended upon sinking a shaft on either side to the depth of 450 feet, and driving a headway a short distance under the sea.

The project of a tunnel under the North River from New York to Jersey City, for railway transportation, for which a company was formed some time ago, gave rise to a long