86 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



usually has no quantitative significance in the measurement of the 

 oxygen consumed in the 10 or 12 minute period. At the end of the 

 period the motor must be run a few seconds longer to insure a complete 

 absorption of the carbon dioxide in the air by the soda lime. 



While the labored respiration is evident to the practised eye in a more 

 rapid rate and a larger amplitude of the excursions of the bell, a pneu- 

 mograph about the chest with attachment for a kymograph record 

 supplies a good picture of the mechanics of respiration and instantly 

 records dyspnoea. The excursions of the bell may be directly written 

 on a kymograph by attaching a light pointer to the counterpoise, though 

 the continuous upward trend of the curve as the oxygen is absorbed 

 will permit of but short records on the kymograph drum of standard 

 height. 



SPIROMETER. 



The spirometer used is a modification of the form of spirometer em- 

 ployed in the universal respiration apparatus, the two chief differences 

 being (1) the recessed part which contains the mechanical blower and 

 (2) the unusual length of the bell. The first provides space for the 

 blower without intricate connections and absolutely precludes leaks. 

 It is a feature of the apparatus that has proved especially satisfactory 

 in practice. The bell is made of sufficient size to allow not only for a 

 full excursion if a deep breath is taken, but also for a considerable con- 

 traction in total volume of the air in the ventilating circuit as the oxy- 

 gen is consumed. 



To minimize the labor of breathing, the bell is delicately counter- 

 poised by a weight (see X, figure 3) on the end of a silk cord running 

 over a light aluminum pulley, Z, at the top. A pointer attached to the 

 counterpoise shows, on a millimeter scale, the fluctuations in the height 

 of the bell. To indicate accurately the somewhat large temperature 

 changes a light-weight thermometer,^ T, is inserted permanently in the 

 top of the bell. To avoid getting water on the blower and consequent 

 electrical damage, with danger of setting fire to the insulation in the 

 oxygen-rich atmosphere, the water level in the spirometer should be 

 considerably lowered when the apparatus is to be moved on an uneven 

 floor. 



ADJUSTMENT TO SUBJECT. 



Almost universal adjustment of the mouthpiece is possible by means 

 of the two hand wheels, A and B. (See fig. 2.) The former controls 

 the movement of the 3-way valve and mouthpiece around the extension 

 arm, L, as an axis, and also their location on the extension arm, while 

 B permits raising or lowering the arm L on an upright standard, S. 

 The extension arm can also be swung about S within the scope of the 

 two rubber tubes, W and G. With no further adjustment the arm L 

 may be placed in position fo r a subject either lying in bed or sitting in a 



1 At present a small Fahrenheit thermometer is used, as a centigrade instrument of like weight 

 and temperature range is not available. 



