Chap. XV.

OX MECHANICAL AGENTS.

1093

hours, and knowing by the dynamometer that the traction is 100 kilogrammes, we havefor the force developed in a minute 100 kilogrammes multiplied by 23-4 metres, or 23*4dynamic units, and in 12 hours 1684 great dynamic units, which have produced the usefuleffect expressed by the number 842, half the preceding. By only comparing the forcedeveloped in a minute, and the corresponding useful effect, we have for its measurement theweight of a tub, 375 kilogrammes, multiplied by the height, 23-4 metres, which productmust be divided by 7'5, although the barrel is only elevated in 7.t minutes. The forcebeing 2*34, the useful effect is half, or T17.

Machine established in the Brewhouse called Bon Pasteur , 80 Bue Mouffetard. — Threehorses harnessed to the same machine elevate by means of a pump 155 muids of water toa height of 132 feet, and the duration of work corresponding to this effect varies between4 and 5 hours, according as the pistons of the pump are in good or bad order : this actionof 3 horses is equivalent to 1784 great units, which gives 593 units for each horse.

The diameter of the circle described by the horses is 6 metres, and they make 13 turnsin 5'; each turn is 19 metres, which gives about 0-8 metres as the swiftness per second, thelength of the ordinary step of a horse. The traction of each horse being 100 kilogrammes,the force developed in 4 hours is 1185, almost double the number of the useful action 595.The machine communicates motion to the pumps, or to a mill for grinding malt : thehorses grind in an hour 5 sacks of malt weighing 100 kilogrammes each.

Machine established at the Hotel des Invalides to elevate Water from a Well by a systenlof Pumps. — Eight horses perform the service from 6 in the morning to 6 at night: eachhorse works 6 hours, in two relays of 3 hours each, separated by a rest of the sameduration : 4 horses are harnessed to the machine at once.

There are two reservoirs, one 6*02 metres high from the ground, the other 16*5 metres.The distance from the ground to the level of the water in the well is 19*16 metres, so thatthe height to which the water must be elevated in the first reservoir, which is the largest,is 25*2 metres, the height for the small reservoir 35*6 metres. The quantity elevated in12 hours in the two reservoirs arc respectively 165 and 35 cube metres of water.

The useful effect corresponding to the daily action of the 8 horses will be expressed by165 x 25-2 + 35 x 35‘6, or 5404 dynamic units, which gives for each day 675 units in 6 hoursof work, and 1 87 in a minute for each horse.

The radius of the machine is 4 metres; the horse makes 21 turns per minute, and goesover 63 metres, which gives 1*2 metres for'his swiftness ini". The mean draughtof 4 harnessed horses, as observed by the dynanometer, is 130 kilogrammes for each, whichgives for the force developed in 12 hours four times 130 kilogrammes x 63 metres x 60' x 12hours, or 2358G dynamic units.

I3y comparing this number to the useful effect, expressed by 5404 dynamic units, we seethat this effect is only ^ of the force developed.

Other Observations on the daily Labour of a Horse. —Armallet, engineer of bridges androads, describes a machine with pulleys at work in the coal mines at Blanzy, near Creusot ,Canal du Charolais , moved by two horses, which elevated in 9 minutes coal weighing 450kilogrammes to the height of 130 metres. He added that the effective labour was 8hours out of .the 24: according to these statements, tlifc daily labour will be expressedby 1560 great units. I agree to the first part of the observation, but has the second, rela-tive to the duration of effective labour, been made several months in succession ? It isallowable to doubt this, when we arrive at a result double that which a great number ofexperiments give.

Other Experiments on Transport by Water -Perronet relates an experiment made on the

canal of Loing. A single man drew a boat loaded with 100 milliers, and in 10 days hewent over a space of 110 kilometres, so that his daily labour was 100 milliers transported11 kilometres. Supposing the draught of a man 10 kilogrammes, the work would beexpressed by 110 dynamic units.

He has further observed that a single horse draws a boat of 300 milliers, and goes over8 kilometres in a day: admitting that the draught is 100 kilogrammes, the labour of thehorse will be expressed by 800 units : it is very probable that the forces developed arein fact in the relation of 100 to 800; nevertheless the useful effect produced in a day areonly in the relation of 11 to 24, or 1 to 2*2.

It would be important to repeat these experiments, and to measure the draught corre-sponding to the velocity of men and horses, having relation to the form and swiftness ofthe boat, and to the greater or less resistance of the fluid.

Summary of the Experiments on the daily Labour of Man ; the dynamic unit being theweight of a cube metre of water elevated to the height of 1 metre, or 2208 lbs. avoirdu-pois raised 3*281 English feet.

Dynamic units

We have, for a man walking 7^ hours on a slope of 14 centimetres

in a metre with a burthen of 7 or 8 kilogrammes ... 225

A man walking in a mountainous country without a load - - 140

4 a 3