CATALOGUE. PHILOSOPHY AND. ARTS, PRACTICAL MKCHANICS. 167 



Force of Horses. 



Force. 



Continu- 

 ance. 



Days 

 work. 



Sh. 5.87 



6h. 



Two horses attached to a plough 

 in moderate ground exerted each a 

 force of 150 Fr. Amontons. We 

 may suppose that they went a little 

 more than 2 miles an hour, for 8 ' 



hours. 5.4 8h. 4.3'2 



A horse can draw with a force 

 of 200 pound-s 2i miles an hour for 

 8 hours in the day. 7.33 



Withaforceof 240only 6 hours. 

 Desaguliers. 8.8 



The mean draught of 4 horses 

 was 36 myriogrammes each, or 794 

 pounds. Regnier. This must have 

 been momentary. Supposing the 

 velocity 2 feet in a second, the ac- 

 tion would have been 15.88 1" 



By means of pumps a horse can 

 raise 250 hogsheads of water 10 feet 

 high in an hour. Smeaton's re- 

 ports. 3.64 ih. 



A horse can in general draw no more up a steep hill than 

 three men can carry, that is from 450 to 750 pounds, but 

 a strong horse can draw 2OQO pounds in a cart up a steep hill 

 which is but short. Desaguliers. 



The diameter of a walk for a horse mill ought to be at 

 least 2S or 30 feet. Desaguliers. 



Some horses have carried 650 or 700 pounds " or 8 miles 

 without resting, as their ordinary work; and a horse at 

 Stourbridge carried 11 hundred weight of iron, or 1232 

 pounds, for 8 miles. Desaguliers. 



A horse was exhibited in London, Jan. I8O5, which was 

 stated in the adverdsement to be 20 hands high, 16 feet 5 

 inches long, and 8 feet 2 inches in girt : it vra.s a coarse cart 

 horse, bred at Denham in Middlesex. As nearly as I could 

 measure it, its real height was 19^ hands, or 6 feet 7 inches. 

 It appeared to be very sluggish in its motions. 



Work of Mules. 



Force. 



Cazand says, that a mule works in 

 the West Indies 2 hours outof about 

 18, with aforceofaboutliOpounds, 

 walking 3 feet in 1* 



Continu- 

 ance. 



Days 

 work. 



4.5 2h 40' 1.3 



Inanimate Force, 



Beale's remarks on mills. Ph. tr. 1677. XII. 



841. 

 Cassini and Lahirc on the water required for 



a mill, A. P. I. 28(J. 

 Kratzenstein's thormometrical power fur a 



clock. N. C. Petr. II. 221. 

 *Smeaton on the powers cjf wind and water. 



Ph. tr. 1759. 100. Reprinted 8. Lond. 

 Loriot on raising weights by the tide. A. P. 



1761. H. log. 

 Stedman on the degrees of wind required for 



machines. Ph. tr. 1777. 493. 



Meavy machines can only work about 10 of the year. 



Coulomb on windmills. A. P. 1781.65. 



y A windmill with 4 sails measuring 66 feet Fr. from one 

 extremity to that of the opposite sail and 6 feet wide, or a 

 little more, was capable of raising lOOO pounds Fr, 218 feet 

 in a minute, and of working on an average 8 hours in a 

 day. This is equivalent to tlie work of 34 men as it has 

 been above estimated, 25 square feet of canvass performing 

 about the daily work of a man. 



On a perpetual motion by barometers. Jsich. 

 III. 126. 



Robison says, that a hundred weight of coals burned in a 

 steam engine will raise at least 20000 cubic feet of water 24 

 feet high : this effect is equivalent to the daily labour of 

 8.32 men A steam engine in London, with a 24 inch cy- 

 linder, does the work of 72 horses, and burns a chaldron of 

 coals in a day ; each bushel being equivalent to two horses, 

 and each square inch of the cylinder performing nearly the 

 work of a man. 



If we calculate the quantity of motion produced by gun- 

 powder, we shall find that this agent, though extremely con- 

 venient, is far more expensive than human labour. But the 

 advantage of powder consists in the great rarity of the ac- 

 tive substance : a springer a bow can only act with a mo- 

 derate velocity on account of its own weight ; the air of the* 

 atmosphere, however compressed, could not flow into a 

 vacuum with a velocity so great as 1500 feet in a second ; 

 hydrogen gas might move more rapidly; but the elastic 

 substance produced by gunpowder is capable of propelling 

 a very heavy cannon ball with a much greater velocity. 



It is said that 9 tons of water, falling 10 feet, will grind 

 and dress a bushel of wheat ; cousequently a man might do 

 the same in 33' 30". 



