33 o THE POPULAR SCIENCE MONTHLY. 



as we have seen, to become mischievous in some shape : and that is 

 function the second. To him it is a matter of indifference for a time 

 whether the quantity of material which his food supplies to the body 

 is greater than his ordinary daily expenditure demands, because his 

 energy and activity furnish unstinted opportunities of eliminating the 

 surplus at all times. But the neglect to adjust a due relation between 

 the " income " and the " output " can not go on forever without signs 

 of mischief in some quarter. A tolerably even correspondence between 

 the two must by some means be maintained to insure a healthy condi- 

 tion of the body. It is failure to understand, first, the importance of 

 preserving a near approach to equality between the supply of nutri- 

 ment to the body and the expenditure produced by the activity of the 

 latter, and, secondly, ignorance of the method of attaining this object 

 in practice, which give rise to various forms of disease calculated to im- 

 bitter and shorten life after the period of prime has passed. 



Let it be understood that in the matters of feeding and bodily activ- 

 ity a surplus of unexpended sustenance here referred to as " the bal- 

 ance " is by its nature exactly opposite to that which prudent men 

 desire to hold with their bankers in affairs of finance. In this respect 

 we desire to augment the income, endeavoring to confine expenditure 

 within such limits as to maintain a cash balance in our favor to meet 

 exigencies not perhaps foreseen. But, in order to preserve our health 

 when that period of blatant, rampant, irrepressible vigor which belongs 

 to youth has passed away, it is time to see that our income of food 

 and our expenditure through such activity as we have constitute a 

 harmonious equality, or nearly so. It is the balance against us of 

 nutritive material which becomes a source of evil. And it is a balance 

 which it is so agreeable and so easy to form, and which often so insidi- 

 ously augments, unless we are on our guard against the danger. The 

 accumulated stores of aliment, the unspent food, so to speak, which 

 saturate the system are happily often got rid of by those special exer- 

 cises to which so large a portion of time and energy is devoted by 

 some people. It is to this end that men at home use dumb-bells or 

 heavy clubs, or abroad shoot, hunt, and row, or perform athletic and 

 pedestrian feats, or sweat in Turkish baths, or undergo a drench at 

 some foreign watering-place all useful exercises in their way, but 

 pursued to an extent unnecessary for any other purpose than to elimi- 

 nate superfluous nutrient materials, which are occasioning derange- 

 ments in the svstem, for which these modes of elimination are the most 

 efficient cure, and are thus often ordered by the medical adviser. But 

 as we increase in age when we have spent, say, our first half-century 

 less energy and activity remain, and less expenditure can be made ; 

 less power to eliminate is possible at fifty than at thirty, still less at 

 sixty and upward. Less nutriment, therefore, must be taken in pro- 

 portion as age advances, or rather as activity diminishes, or the indi- 

 vidual will suffer. If he continues to consume the same abundant 



