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Page 18. 
18 CARDIOGRAPH TRACINGS 
4. ON CARDIOGRAPH TRACINGS FROM THE HUMAN 
CHEST-WALL.* 
(Pl. II.) 
On applying the hand over the left pectoral region the movements of 
the heart can be felt with facility, especially at the end of expiration. 
In the following paper an attempt is made to classify and partly 
explain these movements, as they are reproduced by the sphygmo- 
graph. 
The earliest and perhaps the only published observations on these 
curves are by Dr. Marey of Paris,t who gives one trace from the 
human subject and others from the horse, which latter have the ad- 
vantage of being associated with synchronous traces from the interior 
of the ventricle and of the auricle. No previous observations can be 
found as to the relative duration of the different elements of and the 
other peculiarities in the human heart apex traces at different rapidities 
of pulse. 
While the subject is sitting or standing the sphygmograph can be 
made to give a very perfect record of the heart’s movements, as they 
are transmitted to the intercostal tissues, by holding the instrument 
horizontally with the watchwork to the right hand, the plane of the’ 
recording paper, and consequently of the whole instrument, being 
parallel to the floor, and the lever-pad at or near the point of maxi- 
mum pulsation, between the fifth and sixth ribs. While lying, the 
instrument must be held upright, as when wrist traces are taken. 
The movements of respiration cause so much irregularity in these 
traces, that it is advisable to stop breathing while they are being 
taken ; and this should be done at or near the end of a normal expira- 
tion ; it is then found that little or no effect is produced on the heart’s 
action, during the short time, about seven seconds, that the instrument 
is applied. 
It will also be found that quick pulses are more easily taken than 
slow ones, because the heart can only be rendered slow by means 
that make the skin cold and inelastic, or by positions that make the 
application of the apparatus more difficult. 
In all cases the spring carrying the pad should be screwed down 
so as to give its greatest pressure. 
In the account of the traces thus obtained, the rapid beats will be 
* “Journal of Anatomy and Physiology,” V. pp. 17-27. November, 1870. 
+ “Physiologie Médicale de la Circulation du Sang.” Paris, 1863. Pp. 68 and 
121, and elsewhere. 
