IOWA ACADEMY OP SCIENCES. 
53 
continuous record upon paper or smoked surface. With the 
assistance of a jeweler or other skillful mechanic, this and many 
other simple devices maybe made for experimenting upon mus- 
cles, nerves, circulation, respiration, etc., all with but little 
expense. 
During recent work in phsiology at Penn College a recording 
apparatus became very desirable, and steps were taken to con- 
struct an economical one suitable for the occasion. The instru- 
ment, which was finally completed by the aid of jeweler, lock- 
smith and tinner, cost $7.50. It served its purpose admirably, 
and because of its extensive utility and easy manipulation, it 
was deemed advisable to submit a detailed description of the 
machine with the hope that it may assist some one, or be the 
means of exciting interest in such instruments and calling out 
suggestions for their improvement. 
The kymograph, as the instrument is termed, consists essen- 
tially of a firm stand upon which two cylinders are mounted in 
an upright position. The larger cylinder is connected with a 
clock train so that it may be made to rotate upon its axis at 
different velocities, varying from one-half to three revolutions 
per second. 
The stand is of one and one-half inch poplar; length, sixteen 
inches; width, twelve inches. It rests upon four legs which 
are seven inches in length. The cylinders are held upright one 
inch above the stand, by means of a small steel pillar, from 
which an arm extends to the upper ends of the axis of each. 
The cylinders are hollow and light, constructed of sheet brass 
bent upon and soldered to brass frames at each end. Through 
the centers of these frames the axes extend so as to project one 
inch or more beyond the ends of the cylinders. The small 
cylinder is five inches high and three inches in diameter. It is 
placed near the front side of the stand, with the lower end of 
its axis resting in a brass socket, the upper end held by the 
horizontal arm in such a way that it can be rotated easily. The 
larger cylinder is five inches in depth and six inches in 
diameter. The upper end of its axis is supported by a hori- 
zontal arm, while the lowmr end connects by means of a joint 
with a shaft which extends through the top of the stand to the 
clock train below. This clock train is a part of an eight-day 
movement. The steel spring communicates by a train of three 
wheels, with an adjustable fan, attached to a three- sixteenth 
inch shaft, which extends below the brass frame. See plate V 
