354 ON DIGESTION AND NUTRITIVE ABSORPTION. 



is naturally required for the purposes of life ; and which, if noticed and pro- 

 perly attended to, would prove the most salutary monitor of health, and 

 effectual preventive of disease. It is not the sense of satiety, for this is be- 

 yond the point of healthful indulgence, and is Nature's earliest indication of 

 an abuse and overburden of her powers to replenish the system. It occurs 

 immediately previous to this ; and may be known by the pleasurable sensa- 

 tions of perfect satisfaction, ease and quiescence of body and mind. It is when 

 the stomach says, enough ; and it is distinguished from satiety by the differ- 

 ence of sensations, the latter saying too much." Every medical man is 

 well aware how generally this rule is transgressed ; some persons making a 

 regular practice of eating to repletion ; and others paying far too little atten- 

 tion to the preliminary operations, and thus ingesting more than is good for 

 them, even though they may actually leave off with an appetite. 



471. Although no universal law can be laid down for individuals, however, 

 it is a matter of much practical importance to be able to form a correct average 

 estimate ; and there is no more difficulty in accomplishing this than there is 

 in forming tables of mortality. It is by estimating the average duration of life 

 that Insurance Companies make their calculations of the probable duration of 

 any one and though the actual result may, in every individual case, be dif- 

 ferent from that estimate, yet it holds good perfectly well for a large number. 

 It is from the experience afforded by the usual consumption of food by large 

 bodies of men, therefore, that our data are obtained ; and these data are suf- 

 ficient to enable us to predict with tolerable accuracy what will be required by 

 similar aggregations, though they can afford no guide to the consumption of 

 individuals. We shall first consider the quantity sufficient for men in regular 

 active exercise ; and then inquire how far that may be safely reduced for 

 those who lead a more sedentary life. The Diet-scale of the British Navy may 

 be advantageously taken as a specimen of what is required for the first class. 

 It is well known that an extraordinary improvement has taken place in the 

 health of seamen during the last 80 years ; so that three ships can now be 

 kept afloat with only the same number of men, which were formerly required 

 for two. This is due to the improvement in the quality of the food, in combi- 

 nation with other prophylactic means. At present it may safely be affirmed, 

 that it would not be easy to conceive of any diet-scale more adapted to answer 

 the required purpose. The health of crews that have been long afloat, and 

 have been exposed to every variety of external conditions, appears to be pre- 

 served (at least when they are under the direction of judicious officers), to the 

 full as well as that of persons subject to similar vicissitudes on shore ; and 

 there can be no complaint of insufficiency of food, although the allowance 

 cannot be regarded as superfluous. It consists of from 31 to 35^ ounces of 

 dry nutritious matter daily ; of this 26 oz. are vegetable ; and the rest animal ; 

 9 oz. of salt meat, or 4 oz. fresh, being the allowance of the latter. This is 

 found to be amply sufficient for the support of strength ; and considerable 

 variety is produced by exchanging various parts of the diet for other articles. 

 This, however, is sometimes done erroneously ; thus 8 oz. of fresh vegetables, 

 which contain only 1 oz. of solid nutriment, are exchanged for 12 oz. of 

 flour, which is almost all nutritious. Sugar and Cocoa are also allowed; 

 partly in exchange for a portion of the Spirits formerly served out, the dimi- 

 nution of which, especially in the case of boys, has been attended with great 

 benefit. 



472. A considerable reduction in this amount is of course admissible, where 

 little bodily exertion is required, and where there is less exposure to low tem- 

 peratures. In the case of Prisoners, the diet should of course be as spare as 

 possible, consistently with health ; but it should be carefully modified, in indi- 

 vidual cases, according to several collateral circumstances, such as depression 



