LANDOIS ANGIOGRAPH. 



133 



B', retain them in position. On the other tambours are arranged the 

 writing levers, Z and Z'. Pressure on the one tambour necessarily 

 compresses the air and makes the other, with which it is connected, 

 expand, so as to move the writing-lever. This arrangement does not 

 give absolutely exact results ; still, it is very easily used and is con- 

 venient. In Fig. 52 a double 

 arrangement is shown, where- 

 by one instrument, B, may 

 be placed over the heart, and 

 the other, B', on a distant 

 artery. 



ft Landois' Angiograph. -To 

 a basal plate, G, G, are fixed 

 two upright supports, p, which 

 carry between them at their 

 upper part the movable lever, 

 d, r, carrying a rod bearing a 

 pad, e, directed downwards, 

 which rests on the pulse. 

 The short arm carries a coun- 

 terpoise, d, so as exactly to 

 balance the long arm. The 

 long arm has fixed to it at r 

 a vertical rod provided with 

 teeth, h, which is pressed 

 against a toothed wheel firmly 

 fixed on the axis of the very 

 light writing-lever, e /, which 

 is supported between two up- 

 rights, q, fixed to the opposite 

 end of the basal plate, G, G. 

 The writing-lever is equilibri- 

 ated by means of a light 

 weight. The writing-needle, 

 k, is fixed by a joint to e, and 

 it writes on the plate, /. The 

 first - mentioned lever, d, r, 

 carries a shallow plate, Q, just 

 above the pad, into which 

 weights may be put to weight 

 the pulse. In this instrument 

 the weight can be measured 

 and varied; the writing-lever moves vertically and not in a curve, 



