1(56 CATAI.OGUK.— rillLOSOPHY AN<D ARTS, PRACTICAL MECHANICS. 



Forcf. Continu- Days 

 ation. work, 

 height of a chiliometre. Cou- 

 lomb. .412 



With a spade a man doee \l as 

 much as in ascending stairs. Cou- 

 lomb. .391 



With a vrinch a man docs J as 

 much as in ascending staire. Cou- 

 lomb. .258 



A man carrying wood up stairs 

 raises,togeihtr with his own weight, 

 109 chiliogrammesto l chiliometre. 

 Coulomb. .219 



A man weighing i.io pounds Fr. 

 can ascend by stairs 3 feet Fr. in a 

 second for 15" or 2o". Coulomb. 5.22 20" 



For half an hour loo pounds Fr. 

 may be raised i foot Fr. in a second. 

 Coulomb. 1.152 30' 



According to Mr. Buchanan's 

 comparison, the force exerted in 

 turning a winch being made equal 

 to the unit, the force in pumping 

 will be .01 



In ringing 1.36 



In rowing 1 .48 



Allowing the accuracyof Euler's 

 formula confirmed by Schulze, sup- 

 posing a man's action to be a max- 

 imum when he walks ai miles an 

 hour, we have 7i for his greatest 

 velocity, .04 (7^ — vY for the force 

 exerted with any other velocity, and 

 .016!)(7^ — f)' for the action in each 

 case : thus, when the velocity is 

 one mile an hour, the action is .676 

 When two mile» . .964 



Three .972 . 



Four .784 



And when five .5 



And the force in a state of rest becomes ^^, or about 70 

 pounds, with a velocity of two miles, 36 pounds, with three, 

 24 pounds, and with four, 15. It is obvious that in the ex- 

 treme cases, this formula is inaccurate, but for moderate 

 velocities it is probably a tolerable approximation. 



Coulomb makes the maximum of effect, when a man 

 weighing 70 chiliogrammes carrMs a weight of 53 up stairs. 

 But this appears to be too great a load : he considers 1 4 S 



chiliogrammes as the greatest weight that can be raised. 

 I le observes that in Martinique, where the thermometer is 

 seldom below 68°, the labour of Europeans is reduced to 

 one half. 



Harriot asserts, that his pump with a horizontal motion 

 enables a man to do one third more work than a common 

 pump with a vertical motion. See hydraulic machines. 



Porters carry from 200 to 300 pounds at the rate of 3 

 miles an hour ; chairmen walk 4 miles an hour with a load 

 of 1 50 pounds each ; and it is said, that in Turkey there are 

 porters who by stooping forward carry from 700 to 900 

 pounds placed very low on their backs. 



The most advantageous weight for a man of common 

 strength to carry horizontally is 1 1 1 pounds, or if he returns 

 unladen, 135. With wheel barrows, men will do half as 

 much more work as with hods. Coulomb. 



Performance of Men by Machines. 



Force. Continu- Days 

 ance. work. 



A man raised by a rope and 

 pulley 25 pounds Fr. 220 feetlFr. 

 in 145". Amontons. .436 145" 



A man can raise by a good com- 

 mon pump a hogshead of water 1 o 

 feet high in a minute for a whole 

 day. Dcsaguliers. .8?5 .875 



By the mercurial pump, or ano- 

 ther good pump, a man may raise 



a hogshead 18 or 20 feet in a mi- < 



nute, for one or two minutes. I.61 2' 



In a pile engine 551 pounds Fr. 

 were raised 1 foot Fr. in 1", for 5 

 hours a day, by a rope drawn hori- 

 zontally. Coulomb. .64 5h. J2 



Robison says, that a feeble old man 

 raised7 cubic feet of water 11^ feet 

 in 1' for 8 or 10 hours a day, by 

 walking backwards and forwards on 

 a lever. Enc. Br. , .837 9h. .759 



A young man weighing 135 

 pounds, and carrying 30, raised 9i 

 cubic feet ill feet, high for 10 hours 

 a day without fatigue. Robison. 1.106 loh. 1.106 



Wynne's machine enables a man 

 to raise a hogshead twenty feet in 

 a minute. Y. 1-7* ' 



