Abstract :
Medical Research often requires the continual and simultaneous recording of several variable biological quantities. If slowly changing variables, such as blood pressure, heart beat, respiratory movement, have to be recorded simultaneously with the action potentials of a nerve, a cathode-ray oscilloscope with camera attachment has to be used. All nonelectrical variables must, in this case, be converted into electrical quantities. Commercially available transducers, such as pressure gauges, capacity manometer, require much auxiliary equipment and are very expensive; however, satisfactory results can often be obtained by using only simple additions to standard electrophysiological equipment. An example of such simple instrumentation is given in this paper.
