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bly considered as equal to the useful effect transmitted by the wheel. The precautions known to be necessary in applying the brake, were scrupulously observed. The numbers inscribed in the table relate to the periods, during which we observed a great regularity in the oscillations of the brake, and in the velocity of the wheel.
The gauging of the water we had only the power to make by a single method: we noted the depth, H, of the sheet of water on the sill of the gate, and from it deduced the volume of water issuing by the known formula,
H=the vertical depth of the edge of the gate below the level of the head race, was taken at a point (1.50 met.) 4.92 feet above the gate. The constant m, was assumed at 0.4.
We maintained very precisely (by means of a regulating gate,) the surface of water, in the head race, at a constant height during the whole time of the experiments.
Below, when the wheel was stopped, the water backed up to the lower extremity of the inclined plane which terminates the breast. The fall was counted from the surface of the head to that of the tail water, taken at the lower extremity of the inclined plane.
Occasionally the level of the water varied somewhat below; but it is evident that we might elevate its surface sensibly without prejudicing the motion of the wheel, and, consequently, the falls adopted in the calculations are rather too great than too little.
If we cast our eyes upon the following table, we see that it is divided into nine series, of which—
The first three, A, B, C, are relative to expenditures of water, which differ little from (200 litres) 12,200 cubic inches, or 440 pounds per second.
The fourth and fifth, D and E, relate to expenditures of (300 litres) 18,300 cubic inches.
The sixth and seventh, F and G, relate to expenditures of (400 litres) 24,400 cubic inches.
Finally, the last two, H and I, relate to expenditures of (500 litres) 30,500 cubic inches.
The power of the brake did not permit of going beyond this.
Having compared the results recorded in this table, let us observe, that those of the three last series appear superior to what we should have expected, and to what are generally admitted.
As this became known to us during the course of these trials, we redoubled our attention, and verified minutely all the bases of our calculations, in order to see if we could not find errors; but not a single mistake could be discovered, and the regularity of the results. of the three series, G, H, I, to which they relate, render it improbable that any of importance can exist.
The only debatable point is the application of the formula for gauging the water,
in using which we adopted the constant coefficient of 0.4 for m, which is very nearly the average of those resulting from experiment; but of
all the means usually adopted, this, which is the most simple, appeared to me also the least liable to error, when we took care (as we did) to maintain the level invariable during the whole series of experiments. We believe ourselves safe, then, in regarding as true, or rather as approaching very near to the truth, the results of our experiments, which we may sum up as follows:
I. When the water is conducted to the wheel by the three bays of the gate, and when the lowering of the gate is comprised within the limits of (0.15 to 0.20 met.) .49 to 0.65 feet, which corresponds to a volume of water of (400 to 600 litres,) 24,400 to 36,600 cubic inches per second, the effective power of the wheel deviated but little from eighty per cent., (see series G, H, I.)
II. This effective power diminished for smaller volumes of water; it is only seventy-three per cent. for (300 litres) 18,300 cubic inches, and fifty-two per cent. for (200 litres) 12,200 cubic inches, (see series E, C.)
III. The effective power for (200 litres) 12,200 cubic inches, rose to sixty-six per cent., when we employed the two side bays of the gate, and it reached seventy-one per cent., when we used only that of the middle, (see series A, B.)
IV. For an expense of (300 litres) 18,300 cubic inches, there is not much difference between the use of the entire gate, and that of the two side bays only.
V. The velocities of the circumference of the wheel may vary without sensibly influencing the effective power from (1.40 met.) 4.59 feet, to (2 met.) 6.56 feet per second.
At a time when the views of constructors are turned towards the means of realizing the best possible effect from water powers, and when many systems of motors are presented, it seems to me useful to call the attention of the "Société Industrielle," to the good results obtained with a wheel of a simple and economical construction, which may be employed in many circumstances.
Explanations referring to the Table.
met.-French metres, each 3.281 English feet. kil.-French kilogrammes, each 2.20485 avoirdupois pounds, or nearly two and onefifth pounds. km.-A French dynamical unit, being kilogrammes lifted one metre high in a second.
A horse power of 33,000 pounds, lifted one foot high per minute, is nearly seventy-six and one-fourth km.; the horse power generally employed in France, as a dynamical unit, is seventy-five km. A litre is 61.02802 cubic inches, which quantity of water weighs just a kilogramme, so that in measuring this fluid, litres and kilogrammes are identical in weight.
It will be perceived that the clear length of bucket in this wheel is about 124 feet; and that its available force with the entire gate drawn down 0.20 metres, or .656 feet, is about 18 horse power.
This and the preceding prove conclusively, that the same quantity of water confined, so as to form a thick sheet in flowing over the gate, is much more effective on a breast wheel, than when the same volume is used in a thin sheet, the difference here shown being as 52 to 71. COм. PUB.
VOL. IX, 3RD SERIES. No. 1.-January, 1845.
Explosion of the Locomotive Engine "Richmond.”
The Committee on Science and the Arts constituted by the Franklin Institute of the State of Pennsylvania, for the Promotion of the Mechanic Arts, to whom was referred the examination of the causes which led to the Explosion of the Locomotive Engine "Richmond," upon the 2d of September, 1844, respectfully REPORT:
That they have used all the means in their power to collect information upon the subject of the explosion; they examined with great care the remains of the engine, as exhibited at the shop of the Messrs. Norris, and have obtained statements of the facts from all those who were near at the time of the explosion, and those, who, from their position, were in a situation to judge of the condition of the engine.
The following narrative contains all the material facts brought to light by their investigation, and is based entirely upon these facts:The locomotive engine "Richmond," weighing, when in working order, sixteen and a half tons, (33,000 lbs.) was built by the Messrs. Norris, of this city, and placed upon the Reading Railroad. The boiler was constructed upon the same general principles as those of other modern engines of the same weight. The fire-box was forty and a half inches wide at the widest part, forty and a half inches deep, and forty-two and a half inches high; the back plate, into which the flues were inserted, was thirty-six and three-fourths inches in breadth; the crown was nearly flat, and was stayed by seven castiron bridge-bars upon its top, which sustained the crown by means of stay-bolts passing through both crown and bar. These cast-iron bridge-bars were nearly rectangular in their cross section, which varied in dimensions averaging three and three-fourths inches in depth, and one and seven-sixteenths inch in breadth; but the cross section of the solid metal at the stay-bolts was less than this. These bridgebars did not extend entirely across the crown of the fire-box, so as to rest upon its vertical sides, but terminated about one-fourth of an inch short of the bend by which the crown is joined to the sides. They were not in contact with the top of the fire-box, except at their ends, and at the washers of the stay-bolts, but had a space between, which, at their centres, where it was greatest, amounted to about one-fourth of an inch.
The engine was placed upon the Reading Railroad upon the 14th of August, 1844, and continued to run until the 2d of September, with but few and trifling intermissions; the only one of importance of which, was caused by a required alteration in the valve-rod of the cut-off valve gearing, which change was made at the shop of the Messrs. Norris. The greatest amount of load which the engine had, up to this time, pulled, was seven hundred and sixty tons gross, and the greatest pressure of steam to which it had been subjected, is supposed to have been about one hundred and fifty pounds per square inch. After the alteration in its valve-rod, the engine had made eight trips,