4. A SIMPLE SPIROMETER. 
W. G. Tight. 
(Experimented with before the Scientific Association, March 8th, 1890.) 
The apparatus here described and figured on Plate A, Fig. 5, is 
one which was constructed for and used by the class in Practical 
Physiology. The apparatus was constructed for the determination 
of the vital capacity, supplemental, tidal and complemental air, also 
for experiments on the increase of vital capacity by regular exercise 
of the respiratory mechanism. The results were so satisfactory that 
it was thought that others might wish to use the same plan, as the 
construction is very simple. 
A board about 10 in.x 16 in x i in. forms the base ; at the center 
of one end is braced an upright piece i in.x in.x 28 in.; to this 
at the top is also bracketed an arm i in.x in. x 12 in.; a large 
stone jar is used to hold the water and rests on the base board ; a large 
glass jar (in our instrument a zoology preserving jar), having a capaci- 
ty of something over 4,000 c. cm., is graduated from the bottom up 
into 50 c. cm divisions by adding water and marking the different 
levels ; after this is graduated, a small hole in made with a round file 
in the bottom of the jar and a rubber tube with a glass mouth piece 
attached; the jar is then suspended bottom side up over the water jar, 
(by three wires which pass around it), by a wire which passes through 
a small pulley at the end of the arm and then through another nearer 
the standard and having a weight attached to the end of the wire just 
equal to the weight of the jar ; the rubber tube is provided with a 
strong thumT clamp. 
To work the instrument, open the thumb clamp, press the air re- 
ceiver down into the water jar as far as possible ; then by suction draw 
the water up into the air receiver until it is full of water. The re- 
