£66 Prof. Blumenbach on the Xanthoopia of Jaundiced Persons. 
patients, who, after depression of cataract, see the objects, from the 
use of sulphate of copper applied to the diseased eye, on which 
they look with it, of a colour sometimes verging towards blue *. 
And a somewhat similar vitiation of sight is known to take place 
in those who have, for a long time, kept one eye applied to diop- 
trical instruments. Thus the celebrated philosopher, James 
Rohault, after looking, without interruption, for twelve hours, 
at a distant battle, by means of a telescope, from that time 
forth saw every object with his right eye, which he had here fa- 
tigued so much, of a different colour from what it had when 
viewed with the left. And the same circumstance happened to 
myself, after being assiduously employed, for several days, in 
making observations with a compound microscope. 
But what is commonly told of the two celebrated painters, 
J. Jouvenet *(- and Gavin Hamilton J, does not appear at all like- 
ly, viz. that they did not apply the colours with great precision 
in their paintings, because they both laboured under a similar 
organic disease of the eyes, and so could not depict the colours 
of objects with the accuracy of nature. For although we allow 
a disease of this kind, yet we cannot but think that they saw 
their own paints in the same way that they saw the objects 
which they painted, so that they ought to appear to the specta- 
tors tempered in an equal manner, and so as to correspond with 
nature. 
4. On the Prickle at the extremity of the Tail of the Lion. 
Homer §, and many other ancient poets, both Greek and La- 
tin, when they describe an enraged lion, relate that, as Lucan 
says ||, he stimulates himself with blows of his tail. And Pliny, 
indeed, calls the tail the index of the lion’s mind ; for, says he, 
u when the tail is at rest, the animal is quiet, gentle, and seems 
pleased, which is seldom, however, the case ; and anger is 
much more frequent with him, in the commencement of which 
he lashes the ground, but as it increases, his sides, as if with the 
« Jos. Mohrenheim in Wiener. Beytr. zur Practishen Arzneykunde, vol. I. 
Voltaire, in his Siecle de Louis XIV. 
+ According to the opinion of his illustrious friends Winckelmann and Mengs. 
§ Iliad. Book xx. || Pharsalia, lib. i. 208. 
