MOTION IN THE ANIMAL ORGANISM. 



produced, the capacity of increase of mass 

 or of the supply of waste in living tissues 

 must diminish in the same proportion. 



A perfect balance between the consump- 

 tion of vital force for supply of matter and 

 that for mechanical effects occurs, therefore, 

 only in the adult slate. It is at once recog- 

 nized in the complete supply of the matter 

 consumed. In old age more is wasted; in- 

 childhood more is supplied than wasted. 



The force available for mechanical pur- 

 poses in an adult man is reckoned, in me- 

 chanics, equal to the th of his own weight, 

 which he can move during eight hours, 

 with a velocity of five feet in two seconds. 



If the weight of a man be 150 Ibs., his 

 force is equal to a weight of 30 Ibs. carried 

 by him to a distance of 72,000 feet. For 

 every second his momentum of force is 

 = 30x2-5 = 75 Ibs.; and for the whole 

 day's work his momentum of motion is 

 = 30x72,000 = 216,000. 



By the restoration of the original weight 

 of his body, the man collects again a sum 

 offeree which allows him, next day, to pro- 

 duce, without exhaustion, the same amount 

 of mechanical effects. 



This supply of force is furnished in a seven 

 hours' 1 sleep. 



In manufactories of rolled iron it fre- 

 quently happens, that the pressure of the 

 engine, going at its ordinary rate, is not suf- 

 ficient to force a rod of iron of a certain 

 thickness to pass below the cylinders. The 

 workman, in this case, allows the whole 

 force of the steam to act on the revolving 

 wheel, and not until this has acquired a 

 great velocity does he bring the rod under 

 the rollers ; when it is instantly flattened with 

 great ease into a plate, while the wheel gra- 

 dually loses the velocity it had acquired. 

 What the wheel gained in velocity the roller 

 gained in force ; by this process force was 

 obviously collected, accumulated in the ve- 

 locity ; but in this sense force does not ac- 

 cumulate in the living organism. 



The restoration of force is effected, in the 

 animal body, by the transformation of the 

 separated parts, destined for the production 

 of force, and by the expenditure of the active 

 vital force in causing formation of new parts ; 

 and, with the restoration of the separated or 

 effete parts, the organism recovers a force 

 equal to that which has been expended. 



It is plain, that the vital force manifested, 

 during sleep, in the formation of new parts, 

 must be equal to the whole sum of the mov- 

 ing power expended in the waking state in 

 all mechanical effects whatever, plus a cer- 

 tain amount of force, which is required for 

 carrying on those involuntary motions which 

 continue during sleep. 



From clay to day, the labouring man, with 

 sufficient food, recovers, in seven hours' 

 sleep, the whole sum offeree; and without 

 reckoning the force necessary for the invo- 

 luntary motions which may be considered 

 equal in all men, we may assume, that the 

 mechanical force available for work is di- 

 10 



rectly proportional to the number of hours 

 of sleep. 



The adult man sleeps 7 hours, and wakes 

 17 hours; consequently, if the equilibrium 

 be restored in 24 hours, the mechanical ef- 

 fects produced in 17 hours must be equal to 

 the effects produced during 7 hours in the 

 shape of formation of new parts. 



An old man sleeps only 3 hours; and if 

 every thing else be supposed the same as in 

 the case of the adult, he will be able, at all 

 events, to produce half of the mechanical 

 effects produced by an adult of equal weight; 

 that is, he will be able to carry only 15 Ibs. 

 instead of 30 to the same distance. 



The infant at the breast sleeps 20 hours 

 and wakes only four ; the active force con- 

 sumed in formation of new parts is, in this 

 case, to that consumed in mechanical effects 

 (in motion of the limbs) as 20 to 4; but his 

 limbs possess no momentum of force, for he 

 cannot yet support his own body. If we 

 assume, that the aged man and infant con- 

 sume in mechanical effects a quantity of 

 force corresponding to the proportion avail 

 able in the adult, then the mechanical effects 

 are proportional to the number of waking 

 hours, the formation of new parts to the 

 number of hours of sleep, and we shall have : 

 Force expended in Force expended in 

 mechanical effects, formation of new parts. 



In the adult 

 In the infant . 

 In the old man 



17 

 4 



20 



7 

 20 

 4 



In the adult a perfect equilibrium takes 

 place between waste and supply; in the old 

 man and in the infant, waste and supply are 

 not in equilibrium. If we make the con- 

 sumption of force in the 17 waking hours 

 equal to that required for the restoration of 

 the equilibrium during sleep = 100 = 17 

 waking hours, = 7 hours of sleep, we obtain 

 the following proportions. The mechanical 

 effects are to those in the shape of formation 

 of new parts : 



In the adult man = 100 : 100 

 In the infant . . = 25 : 250 

 In the old man . = 125 : 50 

 Or the increase of mass to the diminution 

 by waste : 



In the adult man = 100 : 100 

 In the infant . . = 100 : 10 

 In the old man . = 100 : 250 

 It is consequently clear, that if the old 

 man performs an amount of work propor- 

 tional to the sleeping hours of the adult, the 

 waste will be greater than the supply ; that 

 is, his body will rapidly decrease in weight, 

 if he carry 15 Ibs. to the distance of 72,000 

 feet with a velocity of 24 feet in the second ; 

 but he will be able, without injury, to carry 

 6 Ibs. to the same distance. 



In the infant the increase is to the decrease 

 as 10 to 1, and consequently, if we in his 

 case increase the expenditure of force in 

 mechanical effects to ten times its proper 

 amount, there will thus be established only 

 an equilibrium between waste and supply 

 G 



