chinery, 800 to 900 yards long, and seven feet in diameter. The machines were susceptible of improvement; yet they were already capable of boring sixty-seven yards in a week, at which rate two galleries, seven feet in diameter, could be made to meet in the middle in five years. From the bottom of the Shakespeare Cliff shaft, 155 feet below the surface, another well was sunk 106 feet deeper, passing through the old gray chalk and into the Galt clay, without finding any trace of water. On the French side also two shafts were sunk, and the same favorable results were obtained. The machine with which the tunnel can be bored through the chalk at a much swifter rate than by the ordinary appliances, and which permits the startling project to be entertained as a mercantile venture, is the joint property and invention of Captain English, Colonel Beaumont, and Mr. Pigon. The Southeastern Railway Company, which has contributed the funds for the trialdrift on the English side, has agreed with the French projectors that the trial-work should be extended one mile under the channel from each shore, the headings to be of the same section, seven feet.

The two main headings of the Severn Tunnel, which is being constructed under the bed of the Severn by the Great Western Railway Company, were successfully united, September 26th, after serious difficulties. Both headings filled with water in 1879. The one on the Monmouthshire side was closed up by masses of the loose sandstone through which it passes. The fragments of rock were driven in by water from the adjacent hills which flooded the works. This heading has been bored 11,000 feet from the bottom of a shaft 180 feet deep, and meets the other with only three inches of deviation, although the vibration of the pumps, which had to be kept constantly going, interfered with the fixing of plumb-lines. The headings are seven feet high and seven feet wide. The tunnel will be enlarged to the width of thirty feet, and to a proportional height.

The ancient aqueduct built in the time of the Emperor Augustus, to supply Bologna with water, has been restored through the efforts of Count Gozzadini, and was reopened June 5th. The Roman engineers tapped the Setta near its junction with the Reno, about eleven miles from Bologna, and brought the water to the city in a tunnel running along the banks of the Reno, underneath the hills, and under the beds of the torrential mountain-streams which flow into the river. The tunnel was injured only in the places where the streams had worn down their channels, carrying away the masonry under their old beds, and where the Reno had washed away its clay banks as far back as the tunnel, taking away portions of the aqueduct. The greater part of the aqueduct, when examined before 1864, was found as good as when first constructed. The masonry was as solid as rock. It was of stone and brick, cemented with lime and volcanic sand. The work

of restoration has occupied many years, and has been executed with a skill and thoroughness calculated to make the new work as firm and durable as the old.

A method of destroying garbage by fire has been practiced in Leeds, Blackburn, Warrington, Derby, and other English towns, proving eminently satisfactory, especially in Leeds, which has led the way in these improvements. At Burmantofts, two miles from the center of the city, a six-celled destructor and a carbonizer were erected. The chambers of the destructor, as it is called, were built in brick, lined with fire-brick, and braced together with iron rods. The destructor occupies a space of twenty-two by twenty-four feet, and is twelve feet in height. An inclined road leads down to the top, and another incline from the level of the firing floor to the public road. Each cell is capable of destroying or carbonizing seven tons of refuse in twenty-four hours. The cells consist of a sloping furnace, with hearth and firegate covered by a reverberatory arch of firebrick, with one opening for the admission of refuse, another for the escape of the gases, and a furnace-door for the removal of clinkers. The refuse is emptied on the platform, and shoveled into the cell, falling first on the incline, thence reaching the sloping hearth, whence, when sufficiently dry, it is pushed on to the fire, where, owing to the radiant heat of the firebrick arch, it burns fiercely, the products of combustion being gases, a fine ash, and clinkers. Every cell is provided with an opening large enough to take in infected bedding, diseased meat, etc. The gaseous products of combustion pass through a flue to a boiler, which supplies steam to a horizontal engine driving two mortarmills. In these mills the clinkers are mixed with lime, and ground into an excellent mortar, which sells readily at five shillings a load; while the tin cans and iron are sold for old metal. No fuel of any kind is required, the cinders and other combustibles found in the refuse supplying all that is needed. The carbonizer is used to convert street refuse and vegetable matter into a charcoal, which sells at the rate of thirty shillings a ton. It consists of a group of brick cells, each having a separate furnace. It is twenty-six feet long, twelve feet wide, and fifteen feet six inches high. The chute is fitted with sloping plates, which project from its sides, and form a kind of spiral ledge, which, near the bottom of the cell, takes the form of a fire-block, resting on a wall which divides the contents of the cell from the gases of the fire. The vegetable and other refuse to be converted into charcoal is filled into this chute in a solid mass, the eaves or ledges forming on their under-side a flue, so that the matter is gradually heated as it slips down the well, until, at the bottom, it is surrounded by nearly red-hot fire-brick. The charcoal is withdrawn at the bottom, and is placed in a cooler worked by the steam-engine, and each cell is capable of treating two tons and a half

of vegetable and street refuse in twenty-four hours.

A design for a steam tug-boat for canals, which has been proved by trials on the Saar coal-canal to be free from the objections to the use of steam in narrow canals, is the invention of Paul Jacquel, of Natzweiler, in Alsace. Steamboats have proved useless on ordinary canals, because the waves which are generated by the screws or paddles injure the banks, and for the reasons that the boats are liable to injury in passing through locks, and that they can not carry sufficient cargo to pay expenses. In Jacquel's system of tug-boats the screw is placed in the body of the boat, and is surrounded by a cylindrical casing which receives almost the entire force of the wash, the water passing out astern in a stream so concentrated in direction that the banks are preserved. The water is fed in through two large channels leading from the sides of the boat. The screw itself in its sheltered position is safe from injury. The boat being a tug, and always drawing the same depth of water, can transport a large train of barges at three or four times the speed obtained from horses. The tug being steered by its own rudder, the use of steering-poles, which are very detrimental to the banks, is avoided.

The removal of Flood Rock, a large reef in the middle of the swift and narrow channel entering New York Harbor from Long Island Sound, is the most important of the Hell-Gate improvements, executed at the cost of the Government, under the plans and directions of General Newton. Flood Rock is a ledge of gneiss of similar composition to Hallet's Point Reef, which was cleared away by undermining it and leveling the remaining portions by a single explosion, which took place September 24, 1876 (see "Annual Cyclopædia" for that year). The work on Flood Rock was begun in 1876, but suspended for lack of appropriations during the year 1878, with which intermission it has been prosecuted continuously. The summit of the reef was at all times above water, although only a small portion was visible. By raising upon it retaining walls and cribs, an area of about a quarter of an acre was built up above high water, which afforded a suitable foundation for the buildings and a hoisting-tower at the opening of the shaft. This was sunk from the apex of the ledge to a depth of about 75 feet. The rock which was removed at the mouth of the shaft was utilized at first to fill a deep hole along shore, and then dumped between Little and Great Mill Rocks, a space 800 feet in length, in order to constitute with them the western jetty which will confine the new channel to be formed by the removal of Flood Rock.

The plan of the excavation is the same as that pursued in the leveling of Hallet's Point. The net-work of galleries and cross-galleries covers five acres. Piers, only sufficient in size and number to support the roof of rock which remains, will be left when the mining opera

tions are over. These piers will then be drilled and filled with a sufficient quantity of explosives, and the whole mine will be fired simultaneously. The equivalent of 100,000 pounds of nitro-glycerine will be employed in the explosion, according to the original estimate. After dredging away a portion of the débris it is expected that a channel 26 feet deep, at low water, will be obtained. The length of the galleries completed at Flood Rock at the end of the fiscal year was 13,528 feet; the quantity of rock removed, 39,608 cubic yards. The mining is expected to be completed at the end of the season of 1883. A considerable proportion of the labor of mining is performed by steam machinery, the most approved modern appliances being employed. The four large boilers on the reef can develop 400 horse-power. They furnish steam to five upright air-compressors, which supply air at a pressure of 55 pounds on a square inch to 30 drilling-machines, as well as to the winding-engine, a ventilating-engine, a shop-engine, two mining-pumps, and other machinery. The length of galleries driven during the fiscal year 1880-'81 was 6,211 lineal feet, and the stone removed amounted to 21,528 cubic yards. During the year 9,823 tons of stone were dredged from Hallet's Point, making the total quantity removed since the explosion 81,907 tons. Over two thirds of the area formerly occupied by this reef, the required depth of 26 feet has been obtained. In the remaining one third there are still places where the depth is not over 19 or 20 feet at low tide. The estimated cost of the remaining works at Hell Gate is $2,250,000. This comprises the completion of the work at Flood Reef, the removal of Heel-Tap and the North Brother reefs, and excavations on Frying-Pan Rock. From Buttermilk Channel, between Governor's Island, in the harbor, and the Brooklyn shore, which was obstructed by a large shoal, with a minimum depth of 94 feet at mean low water, about 80,000 cubic yards have been dredged.

The Madras break water, constructed of béton blocks of 27 tons' weight, was subjected to the force of a cyclone on the 12th of November; about 700 feet of each pier was entirely destroyed, and the topmost tier of blocks throughout their entire length was carried away. The failure of the Parkes plan of construction, under the action of a storm which was not more than half as violent as the one which struck the same shores in 1872, will probably lead to the entire rebuilding of the harbor-works. The 27-ton blocks were swept away like shells. The only part of the works which can be utilized in the reconstruction is the rubble mounds. The blocks of the Colombo breakwater, designed by Sir John Coode, are 50 tons in weight, the piers are half as wide again as those at Madras, and, what is most important, the blocks are set or bonded each nearly one half its length over the neighboring block, and this wall has five joggle

holes running from top to bottom. Parkes pronounced the usual practice of bonding unnecessary, and also placed his blocks on the edge, instead of choosing a broad form and laying them flat, thus exposing as little surface as possible in proportion to the weight to the lateral force of the waves.

In the first excavations for the Panama Canal, at Emparador, the nature of the ground was found to be much more favorable than was assumed in the plans. In making the engineers' estimates it was supposed that a stratum of hard rock would be found underlying the soil at a depth of about 12 feet along the route of the canal. In the first borings the instrument descended to the depth of 37 feet without striking any rock, and then, after penetrating a layer of rock only 6 feet thick, went down to the depth of 64 feet without encountering anything but a mixture of clay and soft stone. The route of the canal from one side of the isthmus to the other has been cleared of trees and other obstructions to the width of from 60 to 90 feet, and 125 miles of paths branching out from the canal route have been constructed. The climate has proved terribly fatal to the skilled workmen and superintendents brought from Europe. The work of excavation was stopped during the rainy season and resumed in October. It has been ascertained that no rock excavations will be necessary between Colon and Lion Hill. At the latter station the steam sounding apparatus showed that the excavation will be in soft clay layers formed by the degradation of a greenish pyroxenic rock. At other places the soundings have revealed to the depth of 80 feet a succession of derived rocks growing softer and softer. The mellow soil has also been found unexpectedly deep along the route.

The work of reclaiming the swamp and overflowed lands surrounding and extending south of Lake Okechobee, opening to cultivation a tract covering 17,000 square miles of the area of Florida, has been undertaken by a combination of Philadelphia capitalists. The State has entered into a contract by which one half of the 8,000,000 acres to be redeemed will become the property of the company. This tract embraces every class of Florida soil, much of it being admirable sugar-land, and contains valuable deposits of hematite ore and marl. Lake Okechobee covers an area of 1,000 square miles. The main feeder of the lake is the Kissimmee River, which discharges 207,360,000 cubic feet of water per diem. The rate of evaporation is one third in excess of the inflow, so that for eight months of the year a large portion of the lakebed is dry. During the four rainy months the water overflows vast tracts of the surrounding country. The plan of reclamation is to construct a drainage-canal 21 miles in length and 44 feet wide, to the St. Lucie River. The canal is to have a fall of 1 foot a mile, giving a calculated velocity of 2 miles an hour, and discharging 733,708,800 cubic feet a day. The

plan is similar to the one proposed to the national Government by Colonel Meigs in 1879. The level of the lake is 25 feet above mean low tide. The artificial outlet will greatly diminish its area. In addition to this canal it is proposed to dig another to the Caloosahatchie River, which flows into the Gulf of Mexico, to deepen and straighten the streams which empty into the lake, and to dig lateral drains, and tap the ridges separating the sawgrass from the Atlantic and from the Gulf, thus draining all the extensive tracts of worthless land in that section. The work on the principal canal has been commenced. It is done by steam-dredges, two working side by side and excavating the entire cut as they proceed. They are constructed on the continuousladder principle, working like the buckets in a grain-elevator. The quantity of earth to be removed in the main drainage-canal is estimated at 9,000,000 cubic yards. The excavation will cost, according to the estimate of Menge, the designer, of the dredges, only two cents a cubic yard.

ENGINES, SOLAR. French physicists have addressed themselves with encouraging experimental results to the utilization of the sun's heat for generating the steam to work mechanical motors. If only a minute fraction of the radiant energy of the sun intercepted by the earth could be directly utilized, it would furnish a superabundant supply of mechanical power for all of man's requirements. When the coal-beds, which represent stored-up energy derived from the sun and preserved from a former geological period, have been exhausted, there remains, so far as science is able to predict, no other abundant chemical source of energy. The current supply of solar heat must then be depended upon. The terrestrial forces of wind and water power, into which a portion of the intercepted radiant energy is converted, will probably remain to the end of time the natural agencies upon which the world must rely for the chief part of its mechanical work. In those parts of the earth's surface upon which the direct rays of the sun beat without remission through the whole year, their heating effect can be converted into mechanical power by means of mechanism of sufficiently neat construction and delicate adjustment. The heat of the sun on the earth is estimated to be equivalent to the melting of a crust of ice 103 feet thick, covering the whole surface of the globe, each year. The greater part of this heat is absorbed by the atmosphere. The average heating effect of the sun's rays, at the level of the ground within the tropics, is estimated to be enough to melt a layer of ice 85 feet in thickness. If the heat falling upon one acre could be entirely utilized in producing motive power, it would give 4,000 horse-power for nine hours a day throughout the year.

Mouchot has experimented many years upon the utilization of the sun's heat as a source of

power for operations requiring an elevated temperature. With mirrors of 80 centimetres diameter, he obtains 400° or 500° centigrade of heat, sufficient for the calcination of alum, the preparation of benzoic acid, the sublimation of sulphur, the distillation of sulphuric acid, for concentrating sirups, refining linseedoil, making charcoal in closed vessels, and other such processes. His small solar alembics he can use for distilling essences, for heating the sand-bath, and similar objects. The rays are brought to a focus upon the alembic by the concave mirror. The great mirror of Mouchot has a diameter of 3·80 metres. The form of concentrating mirror used at first did not utilize more than 50 per cent of the solar heat. The new form, devised by Abel Pifre, gives back 80 per cent of the total possible heating effect. The older one was conical, while the new form approaches the parabola, the generatrix being a broken line forming three truncated cones, the middle one having its sides inclined to the axis 45°, the same angle as in the simple truncated cone used in the older form. This reflector presents to the sun an effective area of nine square metres. The boiler, holding 50 litres, is brought to a boil in 50 minutes, and the pressure then rises at the rate of one atmosphere every seven or eight minutes. With this apparatus Mouchot has obtained six times the useful effect given by the other. With a steam-engine of special construction, made movable in its bed to correspond to the direction of the reflector, 100 litres of water per minute are raised three metres. A motor of one horse-power has been constructed, the reflector of which has at its opening a diameter of 5 metres, or an area of incidence of 20 square metres.

EVANGELICAL ASSOCIATION. The following is a summary of the statistics of this Church, as they were published in August, 1881:

Number of local preachers, 611; Sundayschools, 2,016, with 21,773 officers and teachers and 127,557 scholars; number of baptisms during the year, 1,328 of adults and 7,828 of : children; probable value of the 1,534 churches, $3,350,485; number of parsonages, 456, of a probable value of $431,810; amount of “conference contributions," $5,313; of contribubutions for missions, $92,740; of contributions for the Sunday-school and Tract Union, $2,773. The increase in the number of members during the year was 1,674.

EXHIBITION

OF ELECTRICITY AT PARIS. Among the notable events of the year was the International Exhibition of Electricity opened in Paris, August 11th, in the Palace of Industry, in which the World's Fair of 1855 was held. So rapid has been the development of electrical appliances in recent years, that this great building, with its fortyfive thousand square metres of space, barely sufficed for the present display. Indeed, a number of pavilions were erected without its boundaries by numerous exhibitors. The different countries were very fully represented, the largest and most varied exhibit being made by France, which occupied as much space as all the rest of the exhibitors; England, Germany, and America being next in order. While the exhibition was devoted to electrical appli ances of all kinds, the chief feature was undoubtedly the large and varied display of electric lighting—the lamps of both the arc and incandescent type, the machines for generating the current, and the many details of a complete system of this mode of illumination. In the main hall, a large rectangle, two hundred and fifty metres long by one hundred broad, all the various forms of lamps were commingled, producing a dazzling glare of light, that rendered comparison impossible. But in the smaller saloons reserved for the different exhibitors, only the special lamp of each exhibitor was shown, allowing of a correct estimate of each form of light. The display of lamps of the arc type was very full, all of the now well-known, as well as a number of more recent, lamps being shown. The interest, however, centered upon the systems of incandescent lighting, examples of which were exhibited by Messrs. Edison, Maxim, Swan, and Lane-Fox. The arc had already made for itself a permanent place, but about the incandescent lamp there was much doubt. This has been very largely removed by the excellent showing made by these lamps at the exhibition, and several prominent electricians, who have looked with great disfavor upon this method of illumination, have in consequence announced their belief that the problem of household illumination by electricity, if not solved, is at least very near a solution. The most complete of the exhibitions of incandescent lighting was that of Mr. Edison, whose system, from the lamp to the conductors, was shown in detail. A thousand lamps, three hundred in the two saloons

devoted to his exhibits, and the remainder lighting the grand stairway, were operated by his enormous steam dynaino of one hundred and twenty-five horse-power. The Maxim incandescent light was also very fully shown, about two hundred lamps being in operation. The Swan and the Lane-Fox lamp, and the two English incandescent lamps, made good displays, but neither are as complete as the systems of Edison and Maxim.

Outside of electric lighting the exhibition was full and varied, but space can only be given here to a few of the more notable devices, including one or two others which were not illustrated at the exhibition.

Sir William Thomson has made a careful mathematical calculation of the conditions of transmitting water-power from Niagara to Philadelphia, Boston, New York, Montreal, and all places within a radius of three hundred miles. The dynamo-machines of Gramme or Siemens, supplemented by the Faure storage battery, make it demonstrably practicable to transmit the power of water-falls for long distances and use it for mechanical work with less dissipation of energy than in ordinary hydraulic and mechanical contrivances for transmitting power a few hundred yards. He proposes to convey the current by a solid copper wire carried over-head like ordinary telegraph wires. A current of 240 webers can be transmitted 300 miles by a wire inch in diameter, receiving en13 ergy at the rate of 26,250 horse-power from dynamos driven by the Niagara water-fall, and discharging it at the farther end at the rate of 21,000 horsepower. The loss of 20 per cent by conversion into heat in the conductor would not raise the temperature of the wire above that of the surrounding atmosphere more than 20° centigrade. The potential of 80,000 volts on the conductor would not render the isolation of the wire difficult, nor would it be dangerous to manage in the central station; but when applied to miscellaneous practical uses it must be reduced to 200 or 100 volts. This can be done by the medium of the Faure battery. A battery of 40,000 cells can be connected directly with the electric main; and at short and regular intervals a small number of the charged cells can be removed and replaced by new ones. Sets of fifty could thus be constantly replaced, and the charged cells placed in connection with the supply circuit. In electric transmission of power high potential is a condition of economy. The idea of the application of water-power at a distance by electric transmission was first suggested by C. W. Siemens in 1877, and has been made the subject of thorough theoretical study by Sir William Thomson, who stated the results of his calculation in an examination before a parliamentary committee on electric lighting in May, 1879, and called the attention of the British Associa

tion to the subject in an address at the meeting of 1881.

The Gramme machine was the first electromotive device which proved practically valuable. It consisted of a ring of iron, with a coil of insulated wire wound around its rim, rotated between the poles of an electro-magnet. The leading feature was the commutator, which kept the current always running in the same direction and perfectly continuous, and allowed of the current being used to increase the power of the electro-magnet, besides doing the mechanical work required of the machine. The

GRAMME'S DYNAMO-ELECTRIC MACHINE.

same method of economizing the electricity was worked out by Siemens and Wheatstone; but its development by Gramme first led to the practical use of electricity for the generation of light. Various new modifications of the dynamo-electric machine were shown at the Paris International Electric Exposition of 1881. Surprise was caused among the electricians by the exhibition of electrical machines invented in 1860, and described in 1864 by Professor Pacinotti, of Cagliari, which contain all the essential features of Gramme's later invention and some of the improvements which have been added.

A newly invented machine by Dr. Hopkinson consists of twenty-four fixed magnets arranged in two opposite circles with unlike poles facing each other, between which revolves an iron ring in which channels are cut out alternately on the opposite sides. It thus presents square projections, around which as cores are wound bobbins of wire, whose ends are attached to the arms of the commutator. This device allows the current to be taken from any opposite pairs of arms in the commutator by a number of brushes.

The Bürgin machine has field-magnets like. a Siemens machine, and an inside ring, which