ANIMALS. 435 



joints of the back-bone, which is composed of 

 several pieces, "there is a glutinous liquor deposit- 

 ed, 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 

 being drained away from between the numerous 

 joints of the back-bone, they He closer upon each 

 other, and their whole length is thus very sen- 

 sibly diminished ; but sleep, by restoring the 

 fluid, again swells the spaces between the joints, 

 and the whole is extended to its former dimen- 

 sions. 



" 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 hard day's 

 labour, should eat a plentiful suppej, and then 

 get himself weighed upon -going to bed ; after 

 sleeping soundly, if he is again weighed, he will 



