58 
MR. YOUATt’s veterinary LECTURES. 
be one of the most valuable of all the means we possess of discover¬ 
ing the seat, intensity, or results of the diseases of the respiratory 
passages,—I mean auscultation, or the application of the ear to 
the thorax or the throat of the patient, and the observation of the 
sound emitted by the passage of the air through different portions 
of them. The stethoscope would be an inconvenient instrument 
for us,—we could not perfectly adapt it to any part of the surface 
we wish to examine. The side of the face and the ear we can 
accurately adapt to any part. 
Then what we have first to do, and that which I would 
urge you to make yourselves perfectly acquainted with, is the 
sound produced by the rush of the air through the various pas¬ 
sages, when the animal is quiet and in health; and varying in each 
passage according to the calibre of the tube, its situation and its 
depth from the surface. The sound of health being known, a 
departure from it will be immediately recognized ; and experience 
will gradually teach us the disease, or the degree of disease, 
which, affecting the calibre of the tube or the nature of the 
secretion, produces a variation in that sound. 
21ie liespiratory Sound belonging to the Trachea. —The 
healthy sound proceeding from the trachea is that of a body of 
air passing uninterruptedly through a smooth tube of somewhat 
considerable calibre. I know not what better to liken it to than 
the sound of your forge-bellows when not too violently worked. 
Indeed it is the very sound, somewhat varying however in different 
horses, according to the size of the windpipe; and most certainly 
varying if the horse is disturbed, although in a very slight degree. 
Gentlemen, do not treat this with the derision and contempt with 
which, I am ashamed to say, I have seen auscultation regarded 
by some ; and so regarded because they knew nothing about it. 
Put it to the test of experience—I ask no more. 
Applied to Laryngitis. —I will suppose that you are acquainted 
with the healthy sound. You apply your ear to the base of the 
windpipe, and you find that the bellows are moderately working. 
The air rushes in and out without interruption. There is no disease 
there, and there is not much within the chest, or you would detect 
it by the loudness or the interruption of the murmur. You gradually 
creep up towards the head, and you soon begin to recognize a little 
gurgling rattling sound ; and as you approach the larynx, it is 
more decided,mingled with an occasional wheezing, whistling noise. 
What surer proof can you have that here is the impediment to 
the passage of the air, proceeding from thickening of the mem¬ 
brane and diminution of the passage, or from increased secretion 
of mucus, which bubbles and rattles as the'air passes? By the 
degree of rattling or of whistling you will judge which cause of 
