54 
IOWA ACADEMY OF SCII;NCES. 
The fan consists of two veins of sheet brass two by one and 
one -half inch, arranged upon a horizontal shaft, so that they 
may be turned edgewise to the air to admit of very rapid 
motion, or flatwise to admit of very slow .motion. The move- 
ment of the large cylinder is further controlled by means of a 
lever, which may be applied against a smaller wheel in the 
train. When applied the machine stops running readily. A 
number of improvements are contemplated which will increase 
the number of uses for which the instrument is adapted. It 
will then, in all probability, possess many points of superiority 
over the foreign instrument. 
In plate V the instrument is represented as a kymograph. 
A chronograph pen should be represented below the mercury 
manometer. A roll of paper four inches wide is supported on 
a pivot near the end of the stand opposite the large cylinder. 
The paper is then passed round the smaller cylinder to be 
fastened by a wire clamp to the larger. When the machine is 
in motion the paper is slowly drawn round the smaller cylinder 
and wound about the larger. In addition to the study of nor- 
mal pressure of the blood, records of other interesting and 
instructive experiments, may be secured as in the following: 
1. Effect of stimulating the depressor nerve. 
2 . Effects of stimulating the vagus nerve. 
3. Effects of severing one or both vagus nerves. 
4. Effect of various poisons upon the circulation. 
To use the instrument as a pneumograph or myograph, all 
parts may be removed from the top of the stand except the 
larger cylinder and its support. This cylinder is then taken 
from its position, covered with smoked paper, then replaced, 
ready for use in the study of respiration as muscularation. With 
Marly’s tambour the instrument becomes a pneumograph and 
records may be taken of: 
1. Movements of various regions of the chest in normal 
respiration. 
2. Effect of cutting or stimulating the vagus nerve. 
3. Effect of cutting or stimulating the laryngeal nerves. 
Effects of negative and positive ventilation also are recorded 
by proper levers, etc. 
The single cylinder with smoked surface forms a good 
myograph, when experiments like the following may be per- 
formed: 
