ernor in order to accelerate the clock one second per hour. This form of governor possesses the advantage that it checks any acceleration of the clock more promptly than when friction rubbers are carried by the governor balls; and it is also easy to adjust.-12 4, X., 460.

INHALATION OF OXYGEN MIXED WITH AIR, BY DIVERS, ETC.

It is stated by Gaudin that, in repeating the experiments of Touzet, by the inhalation of a mixture of equal parts of air and oxygen, he experienced an unusually comfortable sensation, which so far removed the disposition to continue respiration that he could hold his nose and close his mouth without any discomfort for five minutes-a fact which, he sug gests, may be of service to divers.-14 C, CCXIII., 1874, 531.

NEW SPEAKING AND HEARING TRUMPET FOR DIVERS.

An apparatus, patented by Bremen & Co., of Kiel, and introduced for trial into the German Imperial navy, not only enables the diver to communicate with those at the airpump, but also to hear distinctly, to a depth of sixteen fathoms, every word spoken at the surface. The absolute safety of the diver being thus secured, it is expected they will be able to work for smaller wages, thus rendering their services available in many cases in which they would otherwise be too costly. It is said that the invention is very simple, and can be attached, without much expense, to any diving ap paratus. The main principle involved is the application of vibrating metallic plates for the propagation of the sound, without, however, allowing them to come in contact with the water.-8 C, Nov. 19, 1874, 415.

APPARATUS FOR RECORDING SIGNALS AUTOMATICALLY.

Mr. W. Smith gave an account before the British Association of an apparatus devised by him for recording signals automatically, on a paper, in connection with the movement of railway trains, so as to show exactly the circumstances under which the movements of the train had been directed and executed. The apparatus itself records: 1. The direction given and received for regulating the movements of trains. 2. The movement of every signal of every kind or description. 3. The movements of the points and other por

tions of the road and way affecting the movements of trains or engines. 4. The passing of trains in every direction; and, 5. The time and relation to such movements, etc., all in a succinct form, upon the same roll or strip of paper. These results are obtained by connecting with the reciprocating parts of the points and signal-working, or with the interlocking gear, a peculiar arrangement of electric contact making and breaking apparatus, acting through a simple electromagnetic contrivance, which, in turn, operates on and deflects a pen or style, which records upon the strip of paper the movements in question.-15 A, Sept. 5, 1874, 323.

HISTORY OF DUPLEX TELEGRAPHY.

In an investigation into the mathematical theory of the workings of duplex telegraphy, the author, Mr. Schwendler, electrical engineer of the Indian government, gives a short sketch of the history of duplex telegraphy, in which he states that as early as 1849 Messrs. Siemens & Halske, of Berlin, took out a patent in England for the simultaneous transmission of a plurality of messages. In 1854 Dr. Gintl, of Vienna, effected the practical solution of the same problem by employing an electro-chemical method, and in the following summer a differential method was independently arrived at by Siemens & Halske, of Berlin, and by Frischen in 1855. In Sweden Edlund employed a differential method, which he had invented in 1848. The theory of Zantedeschi-namely, that of distinguishing electric currents passing simultaneously from opposite directions through the same conductor, without in any way interfering with each other, and on which that physicist has claimed the honor of having first suggested the idea of duplex telegraphy-is characterized by Schwendler as being in direct opposition to the electrical laws which were already known in 1829. None of the above methods had any extended application; they appear to have been attempted doubtingly, and were generally rejected as impracticable. Only recently, after a torpid existence of almost twenty years, has duplex telegraphy secured the amount of public interest it rightly deserves; and to Mr. Stearns, of New York City, is due the credit of having appreciated its value, and by means of his own inventions proved its thorough practicability. The invention of the

duplex method ranks second in importance only to Steinheil's discovery in 1837 of the feasibility of employing the earth to complete the electric circuit, instead of a return wire. Of the causes that have thus delayed the introduction of so important a system, perhaps the most striking was the fact that the invention was twenty years ago in advance of the age; and again that the telegraphic profession, young as it is, is far more conservative than is good for the advance of telegraphy.-7 A, XLVIII, 122.

BALLOON VOYAGE FROM BUFFALO TO NEW JERSEY.

A very interesting and in some respects remarkable balloon ascension was made on the night of the 4th and morning of the 5th of July, 1874, by the well-known aeronaut S. A. King, of Boston. The ascent was made at Buffalo about six o'clock Saturday evening. The course of the balloon was at first slightly east of south, and gradually changed more to the eastward, until a landing was effected at Salem, New Jersey, about seven o'clock Sunday morning, the entire distance traveled in thirteen hours being, in a direct line, nearly 350 miles. The latter part of the journey lay in the path of the terrible tornado which swept over Eastern Pennsylvania and New Jersey on the afternoon of the 4th of July, and which caused great destruction of crops, etc. The balloon employed in this trip is, with two exceptions, the larg est ever built in this country, having a capacity of 91,000 cubic feet. The greatest height attained above the earth's surface was 9750 feet, at which elevation the temperature was 68°, it being then a quarter before seven in the morn ing. Coggia's comet was watched with much interest, and was seen with great distinctness through the early half of the night.-Boston Journal, July 10, 1874.

DISASTROUS TRIP OF THE BALLOON "ZENITH."

The disastrous termination to a balloon ascent lately undertaken in France, in the interest of science, has attracted much attention in Europe; this occurring in the case of the balloon Zenith, on the 15th of April, 1875. On that date M. Gaston Tissandier and M. Crocé-Spinelli took passage in the Zenith, which was in charge of M. Sivel, the special object of the ascent being the determination of the quantity of

carbonic acid gas contained in the atmosphere at an altitude. of 24,000 feet. The experiment of the inhalation of oxygen, after attaining a considerable altitude, was tried, to ascer tain its effects; but at a height above 22,000 feet M. Tissandier fainted. He was shortly afterward awakened by M. Crocé-Spinelli, who warned him to throw over some ballast, which was done. He then fell asleep for about an hour, and on awakening found the balloon descending at a terrific rate. No more ballast was to be thrown away, and his two friends were suffocated. Their faces had turned black, and the blood was flowing from their mouths and noses. M. Tissandier's only resource was to cut the grapnel rope a little before the instant when the car should strike the ground, and the balloon was torn open to stop it. It was finally caught on a hedge about 190 miles southwest of Paris.

The temperature of minus 10° Centigrade was observed. at the height of 22,960 feet, but it was supposed the altitude. to which the balloon had ascended was considerably greater, the indication of the self-registering barometer being 14,000 meters, or eight miles.-12 A, April 24, 1875, 495.

CASING FOR STEAM-PIPES, ETC.

The following composition for casing steam-pipes, etc., is recommended by a German association of engineers as equal in effect to that of Leroy, while it is cheaper: Mix well 120 parts, by weight, of finely ground limestone, 350 of finely ground stone-coal, 250 of finely ground clay, 300 of flue-dust (from the boiler flues), 600 of water, 10 of sulphuric acid of 50° Baumé, and 15 of hair. The place to be covered, warmed if possible, is coated with this mass in layers, from half an inch to 1 or 2 inches thick, and when finished may be painted.-14 C, CCXIII., 1874, 169.

CONSUMPTION OF WOOD BY RAILWAYS.

The National Car Builder reports that at the close of 1873 there were 71,564.9 miles of main lines, and 13,512 miles of sidings and double tracks, making 85,076.9 miles of railway within the United States. Upon these roads the larger proportion of the locomotives consumed wood for their fuel. The number of ties used varies from 2200 to 2800 per mile. Taking 2500 as the mean, it appears that 212,692,500 pieces

of timber, eight feet long and from six to eight inches between the upper and lower surfaces, are required to supply this single item. The durability of ties varies, with climate, kind of timber, soil, and usage, from four to ten years. Assuming six years as the average life of a tie, the amount required for annual supply must be 35,488,750 pieces, or 94,530,000 cubic feet. In considering this item it must be remembered that a large amount of waste occurs from hewing and other causes. It must also be borne in mind that the demand for timber by railroads, besides that used for ties and fuel, is enormous, including fencing, bridges, buildings, and other structures in great variety and number; that the risk from fires is exceptionally great, and that our require ments in this direction are increasing even more rapidly than our supplies are wasting away.

GOLD-MINING IN THE PHILIPPINE ISLANDS.

According to a letter from Minard to Daubrée, the working of the auriferous quartz in the Philippines has been abandoned, the alluvial deposits having proved much richer in grains and scales of gold. It is associated with fragments of dioritic rocks, as itaberite, with magnetite and titanic iron, the gold occurring in tolerably large grains, while quartz is seldom present. Native platinum is also found with it, and, in the samples sent, small zircons with quadrangular pyramids on each end were recognized, as they usually occur in auriferous alluvium.-3 C, July 27, 1874, 600.

NEW CARBONIC ENGINE.

De Beins, of Amsterdam, has communicated the results of his latest experiments with carbonic acid motive-engines. He has for many years studied the question of the transformation of heat into mechanical power, and in seeking to ascertain the degree of pressure evolved by carbonic acid disengaged from bicarbonate of soda heated in a confined space he found that when the bicarbonate of soda, or of potash, either in the condition of dry powder or of an aqueous solution, was heated in a confined space, a part of the carbonic acid became disengaged, and condensed in a cool part of space, in such a manner that at the temperature of 250°

that