FEVERS. 575 



ceived, and when these become languid, they express debility in 

 a remarkable degree. Nothing is more obvious than the dif- 

 ference between the eye of health and the eye of disease. 



" b. The same debility is expressed by some irregularity in 

 the state of these motions, as by tremor, which, I say, is always 

 an expression of debility arising upon the attempt to exert any 

 motion. Sir John Pringle marks the tremor of the hands as a 

 principal sign of the coming on of typhus or jail fever ; and this 

 irregularity has proceeded to a considerable degree, when that 

 active voluble member, the tongue, is liable to the same tremor. 

 But not only this tremor, which is more decisively an expression 

 of debility, but spasm also, or a fixed and more durable con- 

 traction in various muscles, is to be considered in the same 

 light. A degree of tremor which is liable to end in spasm oc- 

 curs in those parts especially which are liable to more vivid 

 motions, as the eye ; the eyes not only lose their accustomed 

 alacrity of motion, but are absolutely fixed ; and we can observe 

 the spasm from the inequality of the motions of the two eyes, 

 or from their squinting, or the ball of the eye is turned up with- 

 in the upper eyelid ; and the eyelids which have a share in the 

 vivid motions are contracted and shut : hence the oculi conni- 

 ventes are considered as a state of spasm. The irregularity of 

 motion appears in a still more considerable degree, when such 

 spasm affects the lower jaw, and some degree of locked jaw oc- 

 curs. I shall not at present inquire why the jaws in many cases 

 remain free, while causes operate which have a tendency to pro- 

 duce spasm ; why the locked jaw is sometimes the first, and 

 very often the only effect ; and why in certain circumstances the 

 jaw is more liable to be affected by such causes. 



" Convulsive motions also are marks of the same debility. 

 Most of the muscles in different parts of the body are liable to 

 be affected with momentary convulsions ; when the tendons, as 

 those of the wrist, which lie bare, are affected in like manner 

 owing to the motions of the muscles themselves, such motions 

 go under the title of Subsultus Tendinum. The lower jaw af- 

 fected with convulsive motions gives the Stridor Dentium, or a 

 seeming gnashing of the teeth, which arises readily in children 

 from various irritations ; we impute it commonly to worms, from 

 which cause it frequently proceeds; but even in children it 



