530 MR. YOUATTS VETERINARY LECTURES. 
Tournis . It consists in the application of the actual cautery to 
the skull. A kind of branding iron was made, to one end of 
which an N was fancifully affixed. The w r ool was cut off from 
the forehead, and the iron being heated so that resting on a card 
for two seconds it would carbonize but not perforate it, it was 
placed somewhat lightly on the forehead of the lamb. After 
resting there two seconds it was lifted up, and immediately re¬ 
placed with a greater pressure for three seconds ; it was once 
more moved, and again pressed yet more firmly on the skull for 
five seconds. All the lambs of four and five months old under¬ 
went this severe cauterization, and which was effected before the 
summer came on, or the flies could be likely to deposit their eggs 
in the wound. The place selected for the cauterization was over 
the frontal sinuses and between the eyes. This was the pre¬ 
ventive treatment, and according to Nairac it was infallible. 
He operated on many thousands of lambs belonging to himself 
and others, and did not lose one. He continued his experiments 
during fifteen years without a single failure. This was even more 
satisfactory than the knitting-needle of the Ettrick shepherd. 
It was, however, nothing more than a severe branding of the 
lamb on the forehead with the magical ceremony of removing the 
iron so many times, and replacing it with regularly increasing 
pressure, and a cabalistic increasing number of seconds. 
It fails when put to the test .—Some persons, however, began 
to doubt whether this branding on the forehead, severe as it was, 
could destroy the diminutive hydatid that might have existence, 
but was yet incapable of doing mischief; and still more did they 
doubt whether the permanent effect which Nairac described could 
possibly be procured, and they determined to put its boasted pre¬ 
ventive power to the test. Hurtrel Dk4rboval entered the field 
among the rest, and he w 7 as enabled to experiment on a somewhat 
large scale. He had a flock of 174 Merino lambs, and none of 
them a twelvemonth old ; he applied the cautery to ninety-three 
of them, and he left the remaining eighty-one to take their 
chance. Out of the ninety-three no fewer than eight became 
sturdied and died, and only four of the eighty-one were affected. 
Hurtrel D’Arboval, with his usual candour, acknowledges that 
he w r ould not be justified in concluding from this single experi¬ 
ment, that the cauterization predisposed the animal to the pro¬ 
duction and growth of the hydatid ; but he w T as fully warranted 
in concluding that the cauterization had no preventive effect at 
aH. 
Another empiric now appeared in the field .—The branding-iron 
was again used in the same manner, but applied immediately 
over the situation occupied by the hydatid, and on two or three 
