We can point with pride to some substantial engineering work of the past year: notably, the building, launching, and placing the great caisson at the Brooklyn terminus of the East River bridge. An extract from the report of Col. Roebling will be found in the present volume.

It is stated that the great central shaft of the Hoosac Tunnel has reached the grade of the tunnel 1,030 feet below the natural surface.

The Broadway Underground Railway is well underway; the construction progressing while the thoroughfare above is crowded with its endless procession of vehicles.

The St. Louis bridge, under the able engineering skill of Captain Eads, progresses finely.

The removal of the obstruction at Hellgate is continued day and night. These and the work of the coast survey testify to the presence of engineering skill among us.

The European war has not called forth to a large extent the inventive capabilities of our population, while it has had distinctly this effect abroad. Activity, however, among the American manufacturers of arms and ammunition has necessarily followed.

As a proof of the esteem in which American weapons are held abroad it is stated that the Remington Co., N. Y., have exported to Denmark 25,000 breech-loaders, and as many to the Swedish government. Colt's Co., 30,000 Berdan rifles to Russia. Turkey has also been a large purchaser. Nearly the half of the work of Smith & Wesson's manufactory is bought by European parties. And the Union Metallic Cartridge Co. send their products to all parts of the world.

We learn, from the "London Broad Arrow," that "12 of the Gatling guns of 45-bore have been ordered from America for the government absolutely, and 50 additional on the understanding that they will be taken. Meanwhile, 50 more of these guns are being manufactured by Sir William Armstrong, at the Elswick ordnance works, in expectation that they also will be taken by the government. As it is understood to be the intention of the government to arm each of the ships of war with a mitrailleuse, in addition to supplying a certain number to the army, it is clear that several hundreds of this arm will be required."

The new explosives, nitro-glycerine, dualin, lithofracteur, and dynamite have received considerable attention during the past year. Full accounts of dualin will be found in the present volume; it seems to promise well for certain kinds of work, although the

authorities at the Hoosac tunnel do not speak very favorably of it. It consists, as do most of these new explosives, of nitro-glycerine, with some comparatively inert base: in the case of dualin the base is sawdust.

The manufacturers of iron are quickly adopting the latest inventions, but have given us no very new modifications or improvements during the year.

Mechanical stoking is attracting considerable attention, and an able paper on this subject was delivered at the meeting of the British association, which can be found on page 23.

The European war has not added materially to the list of inventions of arms of warfare. The merits of the chassepot and the needle-gun have been actively canvassed, but on account of the physical superiority and training of the German over the French soldier, the trial between the weapons has not perhaps been a conclusive one. The mitrailleuse has also come in for its share of praise and abuse. It is thought to be a good weapon for mowing down a close assaulting column, but not for general field work.

It is stated that the projectiles of the chassepot and the mitrailleuse reached an enormous distance in the recent contests. According to the "Lancet," the number of thigh wounds made by bullets was relatively very great in the late battles; and the wounds made by the French sword-bayonet more difficult to heal than those of the Prussian triangular weapon.

The loss of the "Captain " will necessarily call attention to the safer construction of iron-clads.

At the meeting of the British Association, Captain Rowell presented his claims of the superiority of hemp cables over iron and hemp cables, and asserted that the hemp cable would be 50 per cent. cheaper than the present system.

The recent interruption of telegraphic communication with Europe will result, undoubtedly, in the laying of more cables.

A cable between England and France, from Beechy Head to Cape Antiper, near Havre, is in process of construction. It is to be an independent line, and is much needed on account of the pressure of business upon the other cables.

Considerable attention has been paid lately to the use of wirerope tramways. The late Mr. Roebling, by perfecting the manufacture of iron cables, undoubtedly led the way to this result. In mining districts, on steep inclines, and even on ordinary transportation lines, the telo-dynamic system seems destined to play an

important part. In England, 13 lines, varying from short distances to 4 miles in length, have been constructed, and upwards of 100 miles are in course of preparation or under contract. The Suez Canal is a successful fact.

At the meeting of the British Association, General Heine read a paper on "Lines for Ship Canals across the Isthmus of Panama." He concluded that only two lines were deserving of consideration, because of the expense for constructing and working them. The two lines were, first, from Aspinwall along the line of the railway to Panama, with an extreme elevation of 269 feet, a length of 35 miles through rocks of porphyry and basalt, and with but middling ports of entry; second, from the Gulf of Darien through the rivers Atrato, Caiarica, Paya, and Tuyra, to the Gulf of San Miguel, with an extreme elevation of 186 feet, length 52 miles, through soil composed of alluvial deposit, with some thin ranges of grayish sandstone and schist, and with very good ports of entry. The speaker urged upon Englishmen a greater interest in this canal, which would so materially shorten the marine passage to Australia, the west coast of America, and the islands of the Pacific Ocean.

This year marks the completion of the Mount Cenis Tunnel.

The use of artificial stone is on the increase. In many regions of our country, where stone and timber are scarce, the use of concrete in building would seem to find favor. Among the later inventions may be instanced that of the Rev. H. Highton, of England, which utilizes the refuse of granite quarries.

A paper on International Communication in the present volume will prove of interest to all who are afflicted with sea-sickness. Mr. Bessemer proposes to construct a chamber or state-room which shall accommodate itself to the motions of the ship,-somewhat as a lamp hung upon gimbals. This chamber is to be luxuriously fitted up, and to be carefully shut off from the air of the boilers and engines. The expense of such an arrangement seems to be the only feature that will militate against so desirable an improvement.

The watering of streets with chemicals has attracted favorable attention abroad. At the meeting of the British Association, Mr. J. W. Cooper, who has given much attention to this subject, stated that three streets in the city of Liverpool were watered with salt during the month of July, 1869, with very favorable results,

so much so, that the experiments were continued this year. Mr. Cooper proposes to add a certain portion of the deliques

cent chloride of aluminum to the salts used, and, by its antiseptic qualities, afford a means of more thoroughly purifying thoroughfares.

Photography applied to military purposes is not new, but the English government are making greater use of it than ever before.

Photographs are taken of soldiers exercised in the manual of arms, both in the infantry and the artillery service; of the lading of sumpter mules, and, in short, of everything which can convey information to new recruits in the colonies.

The preservation of meat has long attracted much attention in this country and in Europe. The exportation of preserved meats from Australia is becoming a business of great importance. Since the opening of the Pacific Railroad fruit and meat have been transported to the Atlantic sea-board in closed refrigerator cars, In this connection it is well to notice the increased use of artificial ice. The French company Messageries Impériales, wishing to ascertain what kind of ice would be preferable for the vessels navigating the Suez Canal, caused experiments to be made under identical circumstances, and apparently proved that artificial ice would have the preference over natural ice for transportation, and for refrigerating mixtures. More experiments, however, are needed to establish this fact.

A paper on the continuity of the gaseous and liquid state of matter, by Dr. Andrews, will be found on page 128; the transition from the gaseous to the liquid state is shown not to be abrupt, but that the two states are connected by a continuous change. The writer infers, also, that liquids change to solids by a similar law. The recent experiments made by M. Andre, on the velocity of sound in water, give the velocity as 1206.5 metres per second. Wertheim, it will be remembered, found it 1173 metres per second, and MM.Colladon and Sturm, 1435 metres per second. Koenig's investigation of the vowel sounds, supplementary to Helmholtz' researches on the same subject, are interesting in a philological point of view. He infers from the simplicity of the ratio of the vibrations of the five vowel sounds found in all languages, the reason of their universal adoption.

M. Jamin has extended the use of electric currents to the determination of latent heats and specific heats. In this connection it is well to mention Siemens' resistance pyrometer. This instrument will measure intense heat; it is based upon the principle that metals offer a resistance to the passage of an electrical

current when they are heated, this resistance increasing in a determinate ratio. Efforts have long been made to invent an accurate pyrometer. Experts state that this pyrometer promises to be very useful.

The new galvanic battery, invented by Bunsen, evolves no fumes in working, and is quite constant. Consisting merely of one liquid, a mixture of sulphuric and chromic acids, no porous cells are needed.

The experiments on the Atlantic Cable, conducted by Dr. Gould, can be found on page 155.

The general reader will be interested in the fact that messages were effectually and distinctly transmitted in each direction by the use of an electrometer formed by a small percussion cap containing moistened sand, upon which rested a particle of zinc.

Colonel Woodward, of the Army Medical Museum, Washington, has made a series of experiments in microscopic photography, using the magnesium and electric lights. His results are very successful. The lime light and the magnesium light had been used before in this connection, in England, but not with great

success.

Measurements of Newton's rings made some years since by Fizeau, together with the wave length of the light of the two principal components of the D line of the solar spectrum, show a remarkable coincidence in results obtained by different methods, and further confirm the truth of the undulatory hypothesis. (See page 151.)

66

We incorporate herewith the notes of Professor Nichols, on the progress, during the past year, in Chemistry and Geology. During the year considerable progress has been made in organic chemistry so-called. As a rule, however, much of the work done, and most of the results obtained, appeal to the minds of a very few even among scientific men. Still these researches ought not to be decried by practical men, in the face of such a brilliant result as the artificial production of alizarine. (See page 182.) The artificial product seems to be identical in physical and chemical properties with the natural coloring matter, and is already manufactured on a considerable scale. Worthy of mention, also, is the synthetical construction of indigo-blue, by Emmerling and Engler (see page 211), although the method employed offers no prospect of its production in quantities sufficient for manufacturing purposes. Moreover, our knowledge of the constitution of chemical substances, and the laws which