ANIMALS. 201 



of this remarkable variation ; and, I am told, it was first perceived in 

 England b} a recruiting officer. He often found that those men whom 

 he had enlisted for soldiers, and answered to the appointed slanda-d 

 at one time, fell short of it when they -came to be measured before the 

 colonel at the head-quarters. This diminution in their size proceeded 

 from the different times of the day, and the different states of the 

 body, when they happened to be measured. If, as was said, they were 

 measured in the morning, after the night's refreshment, they were 

 found to be commonly half an inch, and very often a whole inch, 

 taller than if measured after the fatigues of the day ; if they were 

 measured when fresh in the country, and before a long fatiguing 

 march to the regiment, they were found to be an inch taller than 

 when they arrived at their journey's end. All this is now well known 

 among those who recruit for the army ; and the reason of this differ- 

 ence of stature is obvious. Between all the joints of the back-bone, 

 which is composed of several pieces, there is a glutinous liquor de- 

 posited, which serves, like oil in a machine, to give the parts an easy 

 play upon each other. This lubricating liquor, or synovia, as the 

 anatomists call it, is poured in during the season of repose, and is 

 consumed by exercise and employment ; so that in a body, after hard 

 labour, there is scarce any of it remaining; but all the joints grow 

 stiff, and their motion becomes hard and painful. It is from hence, 

 therefore, that the body diminishes in stature. For this moisture be- 

 ing drained away from between the numerous joints of the back-bone, 

 they lie closer upon each other ; and their whole length is thus very 

 sensibly diminished ; but sleep, by restoring the fluid again, swells the 

 spaces between the joints, and the whole is extended to its former di- 

 mensions. 



" As the human body is thus often found to differ from itself in 

 size, so it is found to differ in its weight also ; and the same person, 

 without any apparent cause, is found to be heavier at one time than 

 another. If, after having eaten a hearty dinner, or having drank hard, 

 the person should find himself thus heavier, it would appear no way 

 extraordinary ; but the fact is, the body is very often found heavier 

 some hours after eating a hearty meal than immediately succeeding 

 it. If, for instance, a person fatigued by a day's hurd labour, should 

 eat a plentiful supper, and then get himself weighed upon going to 

 bed, after sleeping soundly, if he is again weighed, he will find himself 

 considerably heavier than before ; and this difference is often found 

 to amount to a pound, or sometimes to -a pound and a half. From 

 >vhence this adventitious weight is derived is not easy to conceive ; 

 (lie body, during the whole night, appears rather plentifully perspiring 

 than imbibing any fluid ; rather losing than gaining moisture : how- 

 ever, we have no reason to doubt but that either by the lungs, or per- 

 haps, by a peculiar set of pores, it is all this time inhaling a quantity 

 of fluid, *,vhich thus increases the weight of the whole body upon be- 

 rng weighed the next morning.' 7 * 



* From this experiment, also, the learned may gainer upon what a we<tk foundation 

 <he whole doctrine of the Sanctorian perspiration is built; but this disquisition more pro 

 per.v belongs to medicine than natural history 



