60 GASEOUS METABOLISM OF INFANTS. 



recorded by means of a pneumograph, tambour, and kymograph as 

 used for the same purpose with the respiration apparatus (see figure 7). 



For these 24-hour observations, the kymograph was set at a very 

 much slower speed than in the short-period observations with the 

 respiration apparatus to avoid the necessity of changing the kymograph 

 frequently. The curves were therefore not so sharply defined as those 

 secured when the infant was in the respiration chamber. Numerous 

 curves were obtained with the ward crib recorder during the winter of 

 1913. The kymograph was adjusted by the nurses in charge, often- 

 times during the night, so that certain irregularities in the time record 

 are to be expected. When the infant was removed from the crib for 

 bathing, nursing, or any other cause, the kymograph was of course 

 stopped and a break in the record occurred. Such records as these, 

 which were frequently obtained with infants who were supposed to be 

 lying quietly in the crib throughout the night, are particularly helpful 

 in estimating the needs for energy. 



More recently another form of this recorder has been devised and 

 successfully used. In this later apparatus the adjustment of the crib 

 by means of the spiral spring remains the same. Instead of using the 

 pneumograph and rubber tambour, however, the measurements and 

 manipulation are simplified by substituting an ordinary mechanical 

 counter. This consists of a small revolution counter, such as a Veeder 

 counter, to the axle of which is attached a thin aluminium wheel 119 

 mm. in diameter, with a milled edge. A lever and spring pawl are 

 attached to this toothed wheel in such a way that each upward move- 

 ment of the crib causes the wheel to move slightly in the direction 

 of the hands of a clock. As the crib returns to its original position, 

 any back movement of the wheel is prevented by a second pawl fast- 

 ened to the base of the recording device, but the spring pawl which 

 engages in the teeth of the wheel slides back to its original position 

 without material resistance. Since every upward movement of the 

 crib produces a rotary motion of the wheel, it will be seen that the 

 total movement for any period can be obtained from the number of 

 revolutions of the wheel as recorded by the counter. The wheel is 

 divided into 10 equal divisions and provided with a pointer, so that the 

 readings may be obtained in hundredths of a revolution if desired. The 

 details of the later device are shown in figure 8. 



Two curves obtained with this form of the ward crib recorder are 

 given in figure 9, one of these being for a very restless infant, J. P., 

 November 14-15, 1913, and the other for one much less restless, M. A., 

 November 17-18, 1913. With the restless infant, the toothed wheel 

 made 18.4 complete revolutions during the period from 6 p. m. to 7 a. m. 

 In the curve obtained with the less restless infant, the wheel made 5.2 

 complete revolutions in approximately the same time, i. e., from 5 p. m. 

 to 7 a. m. 



