the proportions adopted, and from the ratio established between the velocities, that the water enters nearly without shock, and issues with almost no velocity, which satisfies, as we know, the general condition of the maximum effect in hydraulic motors.

The wooden cushions, k, k, fixed to the sluice-gate, and slipping between the curved guides, diminish by the rounded form of their lower parts, the effects of contraction, which is, in consequence, nearly destroyed, or at least, very much diminished, on the four sides of the opening

The motion is transmitted to the sluice-gate by three vertical stems, Vol. VI, 3RD. SERIES. No. 4.-OCTOBER, 1843.

21

or rods, 1, l, cut into screws on their upper parts, and around which turn three pinions, all of the same diameter, which act as screw-nuts, and are put in motion by a wheel concentric with the vertical pipe which surrounds the main shaft. This ingenious arrangement insures parallelism of motion in the sluice-gate.

The main shaft passes through the hollow pipe, and has, on its upper part, a cog wheel, which transmits the motion into the interior of the works. At the lower part, this main shaft rests in a socket, which we can raise, as required, by the aid of a lever, and which, by an ingenious contrivance, is continually fed with oil

, notwithstanding it is immersed in water. The lightness of these wheels, the constant supply of oil, which lubricates the rubbing surfaces, and the proximity of the water which keeps it from heating, remove all apprehension of the pivots wearing out, and the experience of many years demonstrates the excellence of the arrangement. The turbines producing a useful effect as great, in proportion to the power expended, when they are submerged, as when they are not, as we shall see further on. M. Fourneyron is in the habit of placing them, so that the level of the upper ring is the same as that of the lowest waters of summer; so that they, at all times, render the whole fall available, which is particularly advantageous at seasons when water is scarce.

As this brief description suffices for explaining the general action of the wheel, we pass on to the experimental results which constitute the chief object of this memoir.

V. Experiments on the Turbines of the Power Weaving Establishment

of Moussay, near Senoues (Department of the Vosges.) Summary description.—There was established in 1836, in the village of Moussay, near Senoues, in the Department of the Vosges, a Power Weaving Establishment belonging to Messrs. Ed. Laurent & Co., which was put to work in the spring of 1837.

My duty having led me at this time into these works, I availed myself of it to request of the proprietors of this establishment, permission to make some experiments with this motor, from which to deduce its effect. My proposition was cordially received by these intelligent manufacturers, and they had the kindness to make all the arrangements necessary to mount the brake, or friction dynamometer, which I sent them. Their works, and their workmen, were liberally placed at our disposal. M. Fourneyron, in person, answered the invitation which was made him, to assist in the experiments; and it is with his aid, that they have been made. The manufacturers and engineers of the neighborhood came to witness, and lend us their assistance in the observations; they were, consequently, made, and verified, by many persons. The motor of the works is a turbine of (0.85m.) 27. feet in exte

2700 rior diameter, of which the vertical shaft transmits the motion directly to the lying shaft of the weaving mill, by means of a single beveled cog wheel.' The water reaches the works by a canal of about (3 m.) 97*** feet broad, and of a regular form, which conducts it into a prismatic

26

reservoir of (5 m.) 16747 feet broad, into which opens a large vertical pipe, communicating by a very short horizontal pipe, with the cylinder which contains the sluices of the turbines. This cylinder, in which the sluice-gate moves, is closed at its upper part, and traversed by the vertical shaft, of which the extremity is of such a height as to allow the lying shaft of the workshop to pass a little below the ceiling of the ground floor. In this way, although the total fall is about 26-3.8 feet, the transmission of the motion is made, in consequence, at any suitable height without hindrance.

VI. Arrangements adopted for the Experiments. The brake, or friction dynamometer, composed of a cast collar of (0.80 m.) 2007 feet in diameter, turned on its outer circumference, was put on the same shast as the turbine, and the lever, placed horizontally, was supported at its extremity by a cord (6 to 7 metres) 1967 to 22:07 feet in length attached to the wood work, in order that it should not bend by its own weight. Over a fixed pulley, placed in a direction perpendicular to that which this lever should preserve whilst it was in equilibrium, passed a leather strap to which was suspended the box that contained the load of the friction dynamometer. To make sure that the lever and strap should preserve a perpendicular direction during the experiments, we suspended to a fixed point, a plumb line, below which the middle line of the lever was to be constantly maintained. The perpendicular let fall from the axis of the wheel on the direction of the strap, or the arms of the lever of the load was (2.505 m.) 8.200 feet in length.

To insure regularity of friction, we kept the cushion of the friction dynamometer constantly wet, in order to maintain the surfaces in the same state of humidity. In consequence of this precaution, the lever remained almost constantly below the vertical of the plumb line, without the oscillations exceeding the space of 1 to 10 of a foot, and without any blows having occasioned violent shocks, as commonly happened when the state of wetness, or oiliness, of the surfaces varied. It also resulted from this continual wetting, that we had not to employ grease in these experiments, and that the temperature of the surfaces in contact, was not elevated even in the greatest velocities, beyond moderate limits, and that to cool them, it was only necessary to continue wetting them during the occasional interruptions in passing from one series of experiments to another.

VII. Gauging of the volume of water expended. It was indispensable to give the utmost possible precision to the means employed for gauging the discharge of water through the orifices of the turbines, and it would have been troublesome to establish a stop-gate in the tail-race, which is arched, and of considerable depth, but the feeding race offering, for that purpose, every facility, we placed at its end nearest to the works, a stop-gate with a waste-board of (2.682 m.) 81800 feet wide, of which the vertical edges (of the over

100

61

fall) distant (0.28 m.) or of a foot from those of the canal, had sharp angles, as well as the sill (or edge of the waste-board,) which was (0.60 m.) 1107 of a foot, at least, from the bottom of the canal. The water, consequently, did not reach the reservoir, or trough, leading to the wheel, until it had passed over the waste-board, the lower edge of which was never flooded by back water during the experiments.

This arrangement lost part of the fall, and reduced it for the experiments to about (7.50 m.) 2400 feet, (1700 feet being lost in the clear fall over the waste-board, necessary to render it a correct meter.-Tr.) this loss was not productive of inconvenience for the esperiments in general; but to be able to make some under the full fali which the works could employ, we subsequently dispensed with the stop-gate, and calculated the expenditure of water by the aid of observations, made during the first series of experiments, proceeding in the following manner.

VIII, Calculation of the volume of water discharged, based upon dimen

sions of the openings of the Turbines. The sum of all the shortest distances measured between the side of one curved guide, and the reverse of the adjacent one, being (0.689 in.)

feet, and the list of the sluice-gate being known for each experiment; we thence easily deduce the sum of the areas of all the orifices by which the water issues, and, consequently, (knowing the head,) the theoretical discharge. By comparing this theoretical discharge with that calculated from the experiments made with the waste-board, we have deduced for each lift of the sluice-gate of the turbine, the coefficient of discharge belonging to the orifices.

For calculating the discharge of water made by the waste-board, we have used the formula,

Q=0.405 LHV2 g H where,

Q=Quantity in cubic metres delivered per second.
L=Length of the opening of the waste-board in metres.
H-Depth of the edge below the surface of the reservoir in metres.

We resolved to adopt this formula, because, first, the sides, or borders, of the overfall, were at the distance of (0.25 m.) a of a foot,

182 at least, from those of the canal; second, the contraction was almost complete on three sides of the opening; and, third, some part of the furniture of the sluices allowed the escape of a little water which did not act upon the turbine. It seems to us. in consequence, that in adopting for the overfall the coefficient 0:405, we have estimated the discharge rather above, than below, the real value.

The following table contains the results of the comparison of the theoretical discharges computed from the dimensions of the orifices of the turbine, with the actual discharge calculated by the above formula.

a

Comparison of the actual with the theoretical Discharge made by the Orifices of the

Turbine of Moussay.
Charge of

Ratio of the ef-
water, or Discharge of water in
No. of ex-
Sum of the difference,

fective dis

one second. Areas of the of the up

charge, to the

theoretical dislower levels. Theoretical. Actual.

charge, or coef

ficiant, of the Sq. Metres. Metres. Cub. Metres. Cub. Metres.

discharge.

periments. Openings.

per and

2 3

IX. Deductions from the results contained in the preceding Table.

We see by this table, that the coefficient of discharge, which, for a lift of the sluice gate of (0.050 m.) 18 of a foot, is at a mean equal to 0.910, reduces itself to 0.80, when the lift is made equal to (0.071, or 0.073 m.) too

or 24, of a foot. This diminution is one consequence of the arrangement of the orifices of emission, which do not occasion much contraction either on the bottom, or on the vertical sides, and of which the upper side is furnished with a cushion of wood rounded on its inner angles, which gives its proper direction to the fluid vein before it reaches the orifice. For the smallest lifts of