ON DISEASES OF THE LUNGS IN HORSES. 
119 
to resound^ or that the sound is didl or dead. The shock occasioning the vibra¬ 
tion may be direct or indirect in its application, it being in the latter case con¬ 
veyed through some intermediate body—hence the distinction between unedi- 
ate and immediate percussion. 
In the Practice of Percussion, Leblanc makes use of a small iron 
hammer and a wooden guard or shield, the latter covered with india-rubber 
upon the surface to be applied to the chest. The sound thus produced ex¬ 
ceeds that elicited by any soft body, such as the hand, against the equally 
soft skin. Such an apparatus, however, is apt to raise two sounds, and, in 
consequence, Delafond after many trials relinquished this—as well as another 
somewhat similar contrivance of his own, for the use of the hand simply. The 
parts to be sounded may be struck back-handed, with the knuckles; or both 
hands may be employed, one serving as the mediator. In fat animals, me¬ 
diate percussion has advantages over immediate, not only on account of the 
external soft parts being thereby compressed, and themselves contributing to 
the sound, but also because we are able with more precision to test certain 
places where sound is but very indistinct, as around the cartilaginous bor¬ 
ders of the ribs. Notwithstanding this, for the common purposes of practice, 
Delafond prefers immediate percussion, and practicable with one hand 
alone; and in performing it, he recommends attention to these rules, viz. 
First; Let the shock or stroke be given perpendicularly to the surface to be 
sounded: an oblique stroke would deaden the sound. Secondly : The ribs 
themselves are to be struck, and not the intercostal spaces, bones being bet¬ 
ter producers and conductors of sound than soft parts. Thirdly: In strik¬ 
ing or tapping, the same force should be employed against every part. 
Fourthly: The same practice, in regard to manner and place, should be 
strictly observed on both sides of the chest, in order that any comparisons 
made, may be correct. 
Pectorae Sounds wtU be found to vary according to the region of the 
chest percussed, the age of the animal, its condition, the full or empty state 
of its bowels, and its peculiar conformation and organization. Even when all 
these circumstances appear alike, resonance may be considerably greater in one 
animal than another. The chest of the horse admits of being percussed 
either upon the right or left side, from behind the shoulder as far as the 
last rib: with a view, how^ever, of rendering the different sounds and their 
modifications distinguishable, it will be best to make some division of this 
space. Suppose we draw an ideal line, corresponding with the posterior bor¬ 
der of the shoulder, and another in the direction of the last rib : the interval 
between these two fixed boundaries we divide by three horizontal lines into 
three equal parts, which we designate regions., superior, inferior, and middle, 
'i'he superior region extends from the scapular line to the last rib, along the 
border of the longissimus dorsi, and includes the superior third of the super¬ 
ficies of the ribs. The inferior region is marked by a line running from the 
elbow along the superior border of the pectoralis magnus, the insertion of the 
external oblique muscle and cartilages of the false ribs, and comprehends the 
inferior third of the said space. The middle region comprises the middle 
third, between these two lines. 
A Difference in the Results of I^ercussion of the chests of men 
and quadrupeds arises from the circumstance, of that of tlie one being hori¬ 
zontal, the other vertical in position, and of that of the horse in particular 
having those large intestines, the emeurn and colon, as well as the stomach, 
contiguous to the diaphragm ; whereas in man the stomach alone partly lies 
within the boundaries of the chest; these hollow viscera necessarily affecting 
the sounds elicited from percussion of the posterior or inferior parts of the 
chest. Had M. Leblanc taken these anatomical differences into account, he 
would not have allowed himself to run into error as he has done. 
