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Two rollers, each 30 inches in diameter, and 36 inches in length, contain on their surface semi-oval cavities, connected together by small channels, which allow the escape of air and excess of material, each cavity or recess communicating by four of those channels with the surrounding ones. These cavities extend in close proximity to each other, in regular rows over the whole length of the rollers, the recesses of every other row being intermediately between those of the adjoining row, in the nature of the cells of a honeycomb, so that small metallic contact surfaces are formed, and the entire surface of the rollers is utilized for compressing the composition into lumps of an egg-shaped form. The shafts of the rollers are cast solid with the rollers, and they are 10 inches in diameter. Each roller weighs over a ton. On top of these is a hopper, 36 inches long, and 30 inches wide, in which the materials to be compressed are discharged from the mixer. In this hopper a series of knives, screwed to a small horizontal shaft, revolve rapidly, and keep the materials in a granulated state.

When the materials to be compressed, happened to contain too much water, which was often the case, the mixture was very plastic, and the lumps were spongy and unfit for use. When the mixture contained the required amount of water, the rollers would spring, and would deliver nothing but half-lumps. Every means were resorted to in order to prevent the springing of the rollers, and to mould complete lumps. All sorts of contrivances, suggested by able mechanical engineers, were tried, without success. Considerable time was required, and a large amount of money was expended to obtain the desired result. The task had been given up by a good many as a hopeless one, still I persevered. I had observed that, when the hopper was almost empty, the shaking of the rollers stopped, and the half-lumps of the last rows remained in the moulds, instead of being discharged on the conveyer below. I concluded from this fact, that the springing of the rollers was produced by an excess of material above the compressing point, and that if I could regulate the quantity of material a little above that point, the springing of the rollers would cease, and perfect lumps would be produced. The thought was a happy one. I devised several attachments to regulate the delivery of the materials on both rollers, with only partial success, until at last I concluded to muffle one roller entirely with sheet iron, and to deliver the materials on the other one. In the centre, above the point of contact of the two rollers, I placed an iron gate, 36 inches long, 3 inches thick, and 3 inches wide, guided

at both ends inside of the hopper, and working up and down, along those guides, by means of two long bolts, threaded at one end, passed through a stationary nut, fastened in a wooden cross-piece above the hopper, and worked by small hand-wheels. By reducing or increasing the space between the bottom of the gate and the roller, more or less material was carried away by that roller. At the point of contact between the rollers, the materials which have been delivered on one roller are pushed into the cavities of the other one, and perfect lumps are formed and discharged on the conveyer below. The difficulty is entirely overcome, and the press has worked well ever

since.

The coal-dust accumulated in the yard is on swampy ground; the tidewater comes up to the middle of the lot, and the capillary attraction draws the water in the coal-pile up as high as seven feet. During dry weather, we obtained from the top of the pile coal sufficiently dry, but when it rained, the coal-dust was so wet that it clogged in the screen, in the chutes under the chain elevators, in the coal pocket, and in the distributor. This was remedied by erecting a gravel-drying apparatus, composed of two drums, 18 feet in length, and 36 inches in diameter, placed on an incline, and heated underneath. The drums revolve slowly; the coal-dust, as it comes from the yard, is fed at one end of each drum; it travels the entire length of the drums in five minutes, while being kept stirred by stationary lifters, fastened inside the drums, and it is finally screened and discharged at the other end perfectly dried.

In the drying oven we had the next trouble. The first plan consisted in carrying the moulded lumps through the oven in 40 minutes, on five endless wire-cloth belts, placed underneath each other, and geared together, so as to travel in opposite directions. The lumps falling from the rollers on the upper belt were conveyed into the oven at the speed of 12 feet in one minute, travelling the whole length of the oven, and falling from one belt to another, until they emerged from the oven on the lower belt, to be discharged therefrom into the waterproofing machine.

When the five wire-cloth belts were loaded, the oven contained about six tons of coal. Under the weight of the fuel the belts would stretch, sag, and drop the greater part of the lumps on the bottom of the oven, where they broke to pieces. The belts were changed several times, and replaced by others of smaller mesh and stronger wire; additional rollers were placed under the wire-cloth to stop the

sagging as much as possible, but the belts would stretch in spite of all, and the use of wire-cloth as conveyers had to be abandoned.

It was also ascertained that the fuel was imperfectly dried, and that the contraction of the clay, used as a cement, could not take place when the Iumps remained only 40 minutes in the oven. The solidity of the lumps was found to depend entirely upon the length of time during which they remained in the oven, and the following tests demonstrated this fact to a certainty:

Three lumps which had been in the oven during 40 minutes, supported a weight of 99 pounds before being crushed.

Three lumps which remained in the oven one hour and ten minutes, stood a weight of 148 pounds before being crushed.

Three lumps which had remained in the oven during six hours, stood a weight of 371 pounds before giving way.

Each one of these lumps came from the same mixer, and contained the same materials, and in the same proportions.

The problem then was not only to modify the oven so that it would hold sufficient fuel during six hours, but to modify it in such a way that the fuel could be discharged by its own gravity, when sufficiently baked. To do this seemed an insuperable difficulty. I studied for weeks one plan after another, until at last I conceived one which I thought would answer the purpose. I submitted the plan to competent authority, and it was approved as a feasible and practicable one.

The plan consisted in doing entirely away with wire-cloth, in suppressing the four lower conveyers, and in using for the top conveyer sections of sheet iron bolted to bridge links of malleable iron, placed at regular intervals, in three endless link chains running in grooves and moved by toothed wheels. The fuel was to be removed from this top conveyer by gates thrown slantingly across it, and it would slide down iron chutes, forming a spiral, upon bars of wrought iron set at an angle across the oven, and resting upon cast-iron racks, placed at the lowest point, 18 inches above the flue. Through those bars and through the mass of the fuel, the hot air was to pass and dry the fuel.

When the fuel was baked it was to be discharged by its own gravity, through a series of gates, on to an outside conveyer, placed alongside the oven, and made of sections of sheet iron, bolted to link chains like the top conveyer. This outside conveyer was to dump the fuel into an elevator, and from this elevator the lumps were to be delivered into the waterproofing machine.

The alterations described above were made, and the whole oven became in this way a kind of coal-bin, holding very near one hundred tons of fuel.

When the oven, modified as stated, was tried for the first time, it contained nearly one hundred tons of good lumps. It was heated to about 300° Fahrenheit, and in about four hours the whole mass of fuel was on fire. It required ten men working two days and one night to extinguish the fire. The fuel was entirely spoiled, but no injury was done to the walls of the oven, or to the inside fixtures of the same. In order to avoid such an accident in the future, the cast-iron flues were covered with loose bricks. Three times in succession the oven was again filled, heated, and when it was supposed that the lumps were sufficiently baked, the discharge gates were opened, and the fuel was found to be as moist as when it entered the

oven.

The oven was allowed to cool, and was carefully examined by Dr. Charles M. Cresson, of this city, and it was ascertained by him that the openings for the admission of air and for the escape of the evaporated moisture were much too small. The fuel, as it seems, had simply been submitted to a steam bath, instead of being baked, and the defect could be easily remedied, according to Dr. Cresson's opinion, by a false sheet-iron bottom, which would bring the air in close contact with the iron flues, and at the same time prevent the fuel from catching fire by radiation from the flues. Dr. Cresson advised larger openings for the admission of air and for the outlet of moisture. The sizes of those openings have been carefully calculated, and there is no doubt that when these alterations shall have been made, the working of the oven will be as satisfactory as that of the balance of the machinery.

The waterproofing process has been tried several times, and has been found to work well. Instead of condensing the vapors of the benzine, as was at first intended, we were compelled, in order to avoid accidents, to remove them by a suction fan. These vapors pass through a system of pipes; they are here mixed with twenty times their volume of atmospheric air, so as to render them innocuous, and they are then expelled above the roof of the building.

It must not be forgotten that the process applied, and the machines used, were entirely novel, and considering all the difficulties in the way of a success, the results obtained have been very satisfactory.

The large amount of money expended, the many disappointments which have occurred, and, above all, the depressed condition of the

coal trade during the last two years, have discouraged some of our stockholders, and we have thus been placed in a financial condition which has prevented the completion of the experiment. In a few days, however, the financial difficulties will also be entirely overcome, a new company will be reorganized, and I hope that in a few weeks the works will be in successful operation, and the fuel will be in the market.

PHILADELPHIA, February 26th, 1878.

66

NOTES ON THE SALISBURY (CONN.) IRON MINES AND

WORKS.

BY A. L. HOLLEY, C.E., NEW YORK CITY.

(Read at the Amenia Meeting, October, 1877.)

THE three principal mines from which the celebrated Salisbury iron ores are obtained are called respectively the "Old Hill,” Davis," and "Chatfield" ore beds, and are situated in the town of Salisbury, Litchfield County, Conn., on the eastern slope of the Tocconue range of hills.*

The Old Hill Ore Bed is a tract of land of 100 acres, originally granted by the General Court in October, 1731, to be laid out by Daniel Bissell of Windsor. It was soon after surveyed and located by Ezekiel Ashley and John Pell. The descendants of Ashley are still proprietors in the mine. The supply of ore has been very abundant, and for many years was easily obtained, but latterly the cost of raising has been greatly increased. Up to about 1840 the average yield was estimated to be about 4500 tons per annum. The production has gradually increased until the average yield at present is estimated at 15,000 tons annually. The largest production in any one year was about 20,000 tons. The proprietors of this mine were incorporated many years ago under the style of "The Salisbury Ore Bed Proprietors.'

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The Davis Ore Bed, named after an early owner, was originally called Hendricks Ore Bed, and was owned before the organization of the town of Salisbury by Thomas Lamb, one of the first settlers

* The data from which the historical portion of these notes has been compiled were collected by the Barnum-Richardson Company, of Lime Rock (Salisbury), Conn.

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