192 PSYCHOLOGICAL EFFECTS OF ALCOHOL. 



absolutely tight; (2) in addition we used a spring clamp, operated 

 from the floor below by a cord, to open and to close a T tube which 

 connected the system with the free ah*. Since this opening was large, 

 an immediate restitution of the equilibrium could be obtained whenever 

 the recorder showed plethysmograph effects. If reasonable care was 

 used in these various adjustments, the device proved usable. 



But recurring plethysmographic effects finally led us to abandon this 

 application of the Wiersma instrument. On the advice of Dr. Carl 

 Tigerstedt we substituted in its place a soft-rubber bulb, strapped as 

 flat as possible over the radial artery. The device was first used in 

 Helsingfors by Professor Robert Tigerstedt; 1 but, as far as we can 

 learn, it has never been published in accessible form. The Tigerstedt 

 method properly requires a flat, pear-shaped bulb, but no such bulb 

 could be found commercially in this country. Round bulbs tend to 

 become concave when flattened against the wrist, making the areas 

 of contact uncertain in size and position. To overcome this difficulty, 

 we used the device of folding a round bulb on itself. In effect, this 

 makes a double flat bulb with a dead space where the fold is open to 

 the air; but if the soft bulb is pressed almost flat against the wrist by 

 a suitable bandage, the effect of this dead space is practically elimi- 

 nated. The resulting movements of the marker proved to be ample 

 in all cases, and not seriously affected either by the plethysmographic 

 changes or by cold. For rapid attachment of the bulb to the wrist, we 

 used an athlete's leather wristband. In this final form the device gave 

 positive results, and caused relatively little trouble. 



The pulse-curve was correlated with the giving of the stimulus, as 

 well as with the reaction of the subject, by means of a stimulus and 

 reaction curve, which was superposed on the pulse-record. The 

 arrangement for securing such correlation was as follows: We used a 

 screw-fed Blix-Sandstrom kymograph, running at the rate of 50 mm. 

 per second, a Dodge duplex recorder, and the electrical sphygmograph 

 as above described. By means of an offset on the shaft, the kymo- 

 graph broke an electric current with every revolution, i. e., every 10". 

 That break operated a signal-lamp on the desk of the experimenter in 

 the balcony. When the signal-lamp went out, the experimenter gave 

 the stimulus word and at the same time pressed a key through which 

 the current passed to one side of the duplex recorder. This gave a 

 stimulus signal superposed on the continuous sphymographic record. 

 Immediately, when the subject reacted, the operator released the key 

 and thus broke the reaction-curve circuit, and registered the reaction 

 on the same continuous line with an error equal to his personal equation. 

 The words were given in groups of 5, so that the properly lettered and 

 numbered kymographic records can be immediately correlated with the 

 corresponding reaction experiments. Between each group of 5, a blank 



Tigerstedt, Hygiea Festband, 1908. 



