230 
ORIGINAL EXPERIMENT ON TIIE SOUNDS OF 
THE HEART. 
To the Editor of “The Lancet.” 
Sir,—I SEND you a short notice of an experiment I have 
performed, with the assistance of my fellow-students, with a 
view to determine the cause of the first sound of the heart. 
Chloroform having been administered to a large *Jog, and 
insensibility produced, an opening was made into the trachea, 
and the exterior part of the thorax removed. Artificial respira¬ 
tion being kept up, the heart was seen contracting and dilating. 
The pericardium was now slit up, and the sounds, which were 
heard through the medium of a stethoscope, were louder and 
more distinct than before the operation. The superior and in¬ 
ferior vena cava, and the pulmonary veins at their entrance to 
the left auricle, were now tightly compressed between the 
fingers, and the heart continuing its action, a stethoscope was 
again applied, and neither first nor second sound was heard. 
After a short interval the veins were allowed to pour their con¬ 
tents into both sides of the heart, and both sounds were instantly 
reproduced. The veins were again compressed, and all sound 
extinguished, notwithstanding the heart contracted vigorously. 
Blood was again let in, and both sounds were restored. 
This experiment was performed on the 1st of this month, and 
successfully repeated on the 10th, on which occasion the heart’s 
action was kept up for forty minutes; and the facts as stated 
above severally attested by my respected anatomical teachers, 
and a number of fellow-students. 
As I am still engaged upon the subject, I hope shortly to 
send you further particulars, with full acknowledgments of the 
great assistance and encouragement I have received from those 
around me. 
I have the honour to remain, Sir, your obedient servant, 
George Britton Halford. 
St. George’s School of Anatomy, Grosvenor-place. 
P. S.—Should any one be induced to try the experiment 
before my next communication, great advantage will be obtained 
by using a small pair of Liston’s bull-dog forceps to compress 
the inferior vena cava. 
