NUTRITION LABORATORY. 293 



Photographic registration of pulse-rate. — The great significance of the 

 pulse-rate as an index of total metabolism, which has frequently been 

 emphasized in publications from this Laboratory, has led to making 

 arrangements for registering photographically the pulse-rates of prac- 

 tically all subjects, both human and animal, in experiments carried on 

 here. The photographic registration apparatus now installed include 

 the Cambridge string galvanometer with its photographic appliances, 

 the Thoma oscillograph, the various forms of smaller string galvan- 

 ometers, and the electrically-driven kymographs. These have made 

 possible an important series of photographic registrations which could 

 not heretofore be obtained — for example, the pulse-rate of a man 

 walking at the rate of 80 meters per minute in the experiment on the 

 treadmill. By the use of a lead-covered cable, extending some 300 or 

 400 meters through the tunnel connecting the various neighboring 

 buildings, it has likewise been possible for us to record photographically 

 (and with a high degree of accuracy) the pulse-rate of a premature 

 infant in one of the wards of the Infants' Hospital. A study of the 

 pulse-rate of premature infants throughout long periods of the day is 

 planned for the immediate future. 



Calorimeter for infants and small animals. — A fundamental research 

 into the conditions most suitable for measuring the heat output of 

 infants and small animals is being carried on in cooperation with Mr. 

 E. H. Lange. Considerable progress has been made towards perfecting 

 an instrument of great sensitiveness and small mass. 



Respiration chamber for pathological cases. — Many pathological sub- 

 jects find difficulty in normal respiration with respiratory appliances 

 fitted to either the nose or the mouth; hence the need has long been 

 felt for a respiration chamber of a type which can be used in hospitals 

 and clinics and in which there may be free and normal breathing. A 

 special form of chamber for use in connection with the Nutrition 

 Laboratory type of respiration apparatus is now being developed. 

 With this chamber it will be possible to control the measurement of the 

 respiratory exchange by means of at least three entirely independent 

 methods. The importance of this control with subjects presenting 

 abnormal metabolism can not be overestimated. 



Calibration of the Krogh bicycle ergometer. — A most ingenious form of 

 bicycle ergometer, based upon the electric-brake principle, has been 

 devised by Professor August Krogh, of Copenhagen. One of these 

 bicycle ergometers has been purchased and a series of calibrations made 

 with it to establish a constant. For this purpose the ergometer was 

 mounted in the chair calorimeter and rotated by an electric motor and 

 gear from the outside. The investigation is still in progress, with the 

 cooperation of Mr. L. E. Emmes. 



Translation of Russian literature. — The accumulation of important 

 Russian monographs in my visits to Russia and the continual receipt 



