516 PHYSIOLOGY AT THE FARM. 



or eleventh part of what the horse accomplishes. By means of 

 a double bucket a man may draw up from a well 120 feet deep 

 36 Ib. of water 120 times in a day the whole effect being 

 equal to raising to the height of one foot 518,400 Ib. Again, 

 by means of a winch, a man easily raises in a short day 845,000 

 Ib. through the height of one foot. 



Several difficulties, however, present themselves in the at- 

 tempt to estimate the exact ratio between the daily labour of 

 a man and that of a horse. Thus, if the above estimate of the 

 daily labour of a horse be taken as the standard namely, 

 12,000,000 Ib. to the height of one foot in a day of six hours 

 and the labour of man in a like length of day be assumed as 

 even so high as the raising of 1,000,000 Ib. to the height of 

 one foot, then the labour-power of a horse must be allowed to 

 be twelve times greater than that of a man. But a common 

 statement on this point is, that the labour-power of a horse is 

 five or six times greater than that of a man ; * and Professor 

 Playfair, in his recent lecture on the food of man, makes the 

 daily labour of a horse something short of eight times that of 

 a man. For this statement he cites Morin ( and Ranking but 

 they make the daily labour of a man in round numbers equiva- 

 lent to the effort of raising 1,500,000 Ib. to the height of a 

 foot, while that of a horse is rated at 12,000,000 Ib. to the 

 same height, the daily labour of the horse being thus regarded 

 as eight times that of a man. But Professor Playfair takes 

 for his ordinary standard of a man's daily labour the exertion 

 of raising no more than 792,000 Ib. to the height of one foot, 

 in which case, as just noticed, the daily labour of a horse is 

 nearly fifteen times greater. Professor Playfair's standard of 

 the daily work of a man is taken from the distance performed 



* Young, 'Natural Philosophy,' by Kelland, vol. i. p. 102. 

 t Morin, translated by Bennet, p. 20. 

 Rankin's ' Applied Mechanics,' p. 397. 



