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THE ANIMAL AS A MACHINE. 



individuals, but families, tribes, and even races, adapt 

 themselves, through natural constitution and peculiar 

 characteristics of body and mind, to special kinds of 

 work. Among the best species, races, tribes, or 

 families, individuals may always be found especially 

 well fitted to perform a specified work ; and among 

 such individuals, the age, state of health, conditions of 

 environment, may produce serious differences at 

 different times. All such variations are noted by the 

 engineer and serve as the basis of his judgment in 

 apportioning work, in assigning duties, and in deter- 

 mining compensation. 



The work once assigned, the person in charge 

 should be expected not only to see that the conditions 

 of best effect are adhered to, strictly and continuously, 

 but to arrange the times and methods of serving 

 meals, the character, amount, and method of prepara- 

 tion of the dietary with a view to insuring the best 

 possible conversion of its potential energy into work 

 and at minimum cost consistent with highest results. 

 Even satisfaction with the bill-of-fare, by promoting 

 appetite and digestion, is an element of success, with 

 animals as well as with men. Periods of rest should 

 be so arranged that the food may be taken neither 

 when fatigue nor immediately succeeding labor may in- 

 terfere with its digestion. Two meals, even one hearty 

 and well-digested meal per day is sometimes found, 

 for this reason, better, on the whole, than a larger 

 number resulting in impaired digestion and defective 

 nutrition. In hot climates, particularly, natives are 

 observed often to be well satisfied with a single meal, 

 taken after a hard day's work ; the precaution being 

 observed to secure an hour of complete rest before 



