Page 267. 
28 CONSTRUCTION AND USE OF A 
The apparatus therefore consists of a cardiograph and of a sphyg- 
mograph, and these are so fixed that they both record on the same 
paper ; and the object to be attained is to get them both to record at 
the same time, the one the movements of the heart’s apex, the other 
the dilatations of the artery at the wrist. 
To obtain this result the sphygmograph is first fixed, as usual, on 
the left arm, and the recording paper is adjusted to its place on the 
watchwork, With the cardiograph in the right hand, the left arm is 
then moved until the attached instrument rests on the board in the 
position shown in the figure, and when there, it is maintained in its 
place by certain pegs and holes in the board, which respectively come 
in contact with the main parts and receive the projections of the instru-. 
ment. 
The arm and attached instruments are then moved until the pad of 
the cardiograph spring is brought in contact with the spot, generally 
between the 5th and 6th ribs, at which the heart’s pulsations are most 
marked; the position of the pad in relation to the board having been 
previously sd fixed as to enable this to be done with facility, the whole 
being maintained in the horizontal position. 
The contact of the cardiograph pad with the chest-wall causes the 
lever to recede from the chest, and it is allowed to do so until its pen 
arrives above the recording paper; the whole apparatus being steadied 
by the right hand. When the levers of the two instruments are both 
found to be moving freely, the watchwork of the sphygmograph is set 
in action by a string (m) held by the right hand, and at the other end 
connected with the stop-block of the train of wheels. The two levers 
recording on the smoked paper give a combined trace of which Fig. II 
is an example. 
As with simple cardiograph traces it is advisable and almost neces- 
sary to hold the breath while the trace is being taken, and further, to 
simplify the working of the instrument, the chest should be empty at 
the time. 
It is evident from the above description that the two levers write 
in opposite directions, and consequently this figure must be turned the 
other way up that the cardiograph trace may be properly. seen, and 
then it must be read from right to left, not from left to right, as the 
sphygmograph trace. 
