86 PULSE RECORDS IN THEIR RELATION TO 



are obtained from the neck, in which the sterno-mastoid is relaxed, 

 by applying to it with light pressure a small receiver, whose width 

 is about 4 cm., and depth 1 cm. 1 The interior of the shallow 

 cup communicates with a delicate tambour carrying a writing 

 style. This simple apparatus is perhaps the most satisfactory as 

 yet employed. The accuracy of its records has been checked by 

 Mackenzie, its originator, and by Gerhardt, by comparisons with 

 the tracings given by light levers directly attached to the skin 

 overlying a superficial vein ; and the movements of the recording 

 tambour and lever, so far as the main waves are concerned, have 

 had their reliability checked by comparison with the tracings 

 yielded by a Hiirthle manometer (Gerhardt). Air transmission is 

 employed, and the curves obtained from the juguW bulb are 

 frequently complicated by the primary wave of the carotid pulse, 

 which in clinical work is not without its advantages, and by the 

 respiratory movements when these are present. Curves are best 

 obtained from the right side of the neck, for here the course of 

 the innominate is shorter and more direct from neck to heart 

 (Friedreich, p. 282) ; clinically they may also be taken from the 

 pulsating liver. 



With regard to the rest of the mechanism little comment is 

 necessary ; when the apparatus described is adjusted to a modified 

 Dudgeon sphygmograph, as in Mackenzie's original instrument, the 

 fitting of a reliable time-marker renders it cumbersome. Another 

 convenient instrument for clinical work is " Mackenzie's ink 

 polygraph," 2 with which tracings of any length and at various 

 speeds may be taken. It allows a simultaneous record of any 

 two given pulsations, and carries a reliable time-marker. The 

 curves from the jugular vein give, considering the indirect methods 

 of determining them, surprisingly constant results, and in this lies 

 their chief justification. 



1 There is a tendency, not without its advantages, towards the use of smaller 

 receivers. 



2 The apparatus, an account of which is published in the British Medical 

 Journal for June 13, 1908, p. 1411, is open to improvement ; more particularly 

 the writing styles, and that portion of the mechanism used for the record of the 

 radial pulse. The momentum of the levers and membranes is considerable, and 

 extraneous movements cannot be entirely excluded. For the interpretation of the 

 main waves it answers its purpose admirably, but for the investigation of the minor 

 waves more delicate apparatus would be requisite. 



It is necessary to insist on the disuse of time markers whose movement depends 

 on the clockwork which drives the paper. 



