FEVERS. 565 



blood, or by a resistance in the right ventricle of the heart to 

 the return of the blood from the veins of the head. The turges- 

 cence of the face, therefore, is a mark only when no difficult 

 respiration or obstruction to the transmission of the blood 

 through the lungs is present. This redness, suffusion, and 

 turgesccnce is not always remarkable over the whole face, for 

 a less degree will produce a particular suffusion, as where the 

 vessels of the eye only are affected, where a redness, or a num- 

 ber of red vessels, appear in the adnata ; but more especially 

 where a fulness of the ball of the eye occurs, sometimes even 

 with a considerable protuberance. When these marks occur 

 without any obstruction through the lungs, they are strong 

 marks of the increased impetus and of obstruction in the head. 



" Sometimes these external marks do not appear, but we per- 

 ceive the increased impetus and tension most obvious in the 

 finer vessels of the organs of sense, and we find no difficulty in 

 explaining in what manner they take place ; the nerves of the 

 senses, as those of the eye and ear, derive their tension from a 

 mixture of blood vessels which nature has industriously connect- 

 ed with them, and the sensibility of the organ is in proportion to 

 this tension, so that the light and noise which were formerly 

 not in the least disagreeable, now become painful. This may 

 arise from a particular irritation of the nervous system without 

 any increased impetus of the blood vessels. But, undoubtedly, 

 that sensibility to light and noise which occurs in fevers, may 

 be commonly taken as a mark of some increased impetus of the 

 blood in the vessels of the head, affecting especially those ex- 

 tremities that are mixed with the nerves of sense. (See Physi- 

 ology, LVI. 3.) 



" To these symptoms I would next join Headach. This is 

 commonly considered as the first of the marks of increased im- 

 petus ; but no morbid symptom is of more difficult theory than 

 headach. Thus I find that sometimes it appears with a slow 

 pulse and palid countenance ; and there certainly it cannot de- 

 pend upon an increased impetus ; headach therefore is to be 

 considered as an expression of the increased impetus only when 

 it occurs with more or less of the symptoms which I have men- 

 tioned. Headach is very often the first symptom in the attack 

 of fevers of the nervous kind, and it is no where more remark- 



