in place is performed by driving pipe. This pipe is an extra thick lap-weld tube eight inches in diameter; the lower end of the first joint is armed with a steel shoe, shrunk on. It is driven by a log used as a maul, much as piles are driven, guides for which are set up in the derrick, and length after length being screwed on and driven down until bed-rock is reached. To facilitate driving, an eight-inch bit is put inside, drilling out the gravel and dirt, and keeping ahead to break any boulders or hard strata, so that the drive-pipe shall not be deflected.

When the drive-pipe is set, the eight-inch hole is continued below the water-bearing rocks, and casing five and five-eighths inches internal diameter is put in, shutting off the water. Then the ordinary fiveand-a-half inch bit is used, and drilling goes on until the oil or gasbearing rock is reached.

It is customary to torpedo a well as soon as drilled through the oil-bearing sandstones, in order to open fissures in the stone, and thus increase the flow. For this purpose nitro-glycerine is used in quantities up to two hundred quarts, or six hundred and sixty pounds, at a time, a good charge being one hundred quarts, costing, exploded in the well, $1 per quart. It is placed in tin cases four inches in diameter, and about eight feet long, which are lowered, one at a time, the last one carrying a firing-head containing ordinary waterproof percussioncaps. The torpedo is exploded by dropping a weight on the caps, or sometimes by a squib or time-fuse.

The flow of oil following the explosion is allowed to go into the air, that the well may be blown clear of loose stones, pieces of tin and iron, etc.; but immediately after this flow has ceased, the two-inch tubing is put in, and connections made with the tank, to save subsequent flows.

A large number of views were shown of the operations of drilling and shooting the well; of the "cities of tanks" at Olean and other places, belonging to the National Transit Company, whose total storage capacity is 42,000,000 barrels; of burning tanks, etc. These iron storage-tanks, which were described in detail by the speaker, were from eighty-five feet to ninety-five feet in diameter, holding from thirty thousand to thirty-five thousand barrels of oil each (forty-two gallons to a barrel). This was supplemented by remarks on the care of oil and gas wells, storage and transportation of oil, and the present

condition of the Northern oil-fields, concluding by a hasty reference to the geological structure of the country.

At the close of the paper, Mr. C. J. H. WOODBURY, on invitation of the chairman, spoke as follows: My experience with natural gas has been supplementary to the portion of the subject considered by the lecturer, inasmuch as my work has been confined to a consideration of its value in the industrial arts, as tending to its successful use, and also what measures will serve to render its use as safe as possible, avoiding in the future such sad accidents as have already wrought serious injuries to persons and property.

The supply from each gas-well will, no doubt, be exhausted in the near future, but the use of natural gas will undoubtedly be possible for some time to come, by reason of new wells.

Whichever of the several probable causes leading to the formation of natural gas be the true one, there is no doubt but that its production has ceased, and that the present supply is merely the draught from a limited reservoir. The use of natural gas has been attended with so many advantages that, irrespective of the supply, it is probable that the days of solid fuel for industrial metallurgy are substantially over. The saving of labor in handling coal, absence of deleterious impurities in gaseous fuel, high temperature of combustion, avoidance of fuel lost in starting or banking fires, all render the use of gaseous fuel a matter of great commercial importance. It has been represented to me that the gain of using natural gas in place of coal, in manufacture of wrought iron, amounted to $2.12 per ton, of which $1 represented the value of the increased quantity of wrought iron made from a given amount of pig iron, and $1.12 the saving in cost of labor and fuel. It is estimated that the increased profits to manufacturers in the Pittsburg district by reason of the use of natural gas amounts to $1,500,000 per annum; and if this be a fact, no one will begrudge the fifty per cent profit said to be made by those who have spent large sums in conducting the gas to the city, taking the risk of the speedy exhaustion of the supply.

Its use for stoves and fireplaces is quite general, the gas being fed from a perforated pipe, under a lot of broken crucible or fire-brick loosely thrown in where the coal is ordinarily placed. These pieces glow like an anthracite fire, with the pale blue hydrogen and marsh gas-flames playing through the interstices. A warmer effect is sometimes obtained by throwing some salt on the refractory pieces used in

the stove, and the yellow sodium-flame is their nearest approximation to a hickory fire. Being without smoke, the inside of these fireplaces is frequently white-washed.

The use of natural gas has not been without untoward incidents by way of numerous accidents, most of them of a serious nature; for it is odorless after being conducted a short distance in pipes, and explosive when mixed with between five and thirteen times its volume of air, differing in intensity, being a high explosive at its maximum, of one volume of gas to about 9.5 or 10 volumes of air.

It is very permeating, and, like hydrogen gas, leaks readily through joints perfectly tight against air, oil, or water. The most ingenious expedients have been devised to make tighter pipe-joints, and also conduct leaking gas away from the pipes to the atmosphere.

With these objects in view, it can be considered reasonably safe if the pressure is reduced, by a pressure governor, to less than one and a half pounds to the square inch; all pipes in yards or buildings should be above ground and away from concealed spaces in walls or floors; the fire should be applied before the gas is let on to a stove.

These rules may appear simple, but there will always be instances of their negligent infraction, rendering the matter of natural gas a live issue in underwriting as long as it is used, especially in houses.

Its candle power is eight and one half, and when burned through large burners gives a flaring yellowish flame, with a large blue center. When carburetted with naphtha the illúmination is better, but is exceedingly unsafe in case of leakage.

A vote of thanks was passed to the speaker, and the meeting was adjourned.

MEETING 342.

Transmission of Power by Belting. —An Account of the Work Done on this Subject in the Mechanical Engineering Laboratory.

BY PROF. GAETANO LANZA.

The 342nd meeting of the SoCIETY OF ARTS was held at the Institute on Thursday, January 28th, at 8 P. M., Mr. Geo. L. Roberts in the chair.

After the reading of the minutes of the last meeting, and the

transaction of some business, the chairman introduced Prof. Gaetano Lanza, who read a paper on the "Transmission of Power by Belting. - An Account of the Work Done on this Subject in the Mechanical Engineering Laboratory."

Prof. LANZA said: It is well known to mechanical engineers that the rules for determining the proper width of leather belting, to carry a given power at a given speed, differ enormously from each other.

No better illustration of this fact can be given than the variety of rules given in the "Use of Belting," by John H. Cooper, a book that finds more or less favor among mechanics. In this book there are grouped together all the different rules that the author of the book could discover as being employed by any man who ever used a belt.

If we set out to compute, by means of a number of the rules heretofore in use, the proper width of belt to carry 30 H. P. when traveling 1500 feet per minute on a pair of 30" pulleys, we shall obtain the following as the results:

The greater part of these rules are no better than guesses, being merely the practice of this or that mechanic, based upon no experimental evidence whatever. Rules of this character will not be considered in this paper, and only those will be discussed which have as their basis some experimental investigation, whether correct or incorrect; but even these differ in their results, in some cases, by as much as one hundred per cent.

During the last two years and a half we have been carrying on a series of experiments in the mechanical engineering laboratory of the Institute, with a view to solving this problem in such a manner as to leave no room for doubt as to the correctness of the results.

The work upon the subject has formed part of the regular laboratory work, and also the subject of two theses,-one by Mr. A. J. Purinton, and the other by Mr. A. L. Merrill.

Before giving an account of this work, and of the results obtained, I will state briefly what has been done by others.

The only experiments of which the writer is aware are the following:

10. By Gen. Morin.

20. By Henry R. Towne, of the Yale & Towne Company.

30. By Edward Sawyer, of Charlestown, Mass.

40. By Samuel Webber, of Lawrence.

5°. By Prof. S. W. Holman, of the Mass. Institute of Technology.

(10.) As to those of Morin, he used a fixed cast-iron drum, over which hung a belt, the ends hanging vertically, and being of equal lengths; these two ends he loaded with equal weights, and then added weight on one side until the belt slipped, and thus determined the two tensions T, on the tight side, and T, on the loose side. He then determined the co-efficient of friction f, from the formula —

He does not state what was the speed with which the belts slipped when he obtained these results.

(2°.) Mr. Henry R. Towne performed his experiments in the same way, only that he allowed his belts to slip at a speed as nearly 200 feet per minute as he could judge by the eye.

He obtained as a result ƒ = 0.58; but he and Mr. Robert Briggs recommend for use two-thirds of this, or f = 0.42.

(3°.) Mr. Edward Sawyer, of Charlestown, used also a fixed drum, and performed the experiments in the same way as the other two, with this exception,- that, when he had loaded the heavy side. sufficiently to make the belt slip, he then placed additional load on