516 Dr. Rattray on the effects of Change of Climate [Jane 16, 



equal to an average gain of 24 cubic inches per man. Column 3 gives the 

 capacity, thirty-eight days later, in the equatorial doldrums and highest 

 temperature of the return voyage (83° F., shade), and shows that in ten of 

 the twelve cases this increase was still further augmented by an average of 

 6k cubic inches from prolonged tropical exposure. It would be interesting 

 to know the limits of this increase, and whether it is, as likely, permanent. 

 The other two cases remained stationary. The total average in the twelve 

 cases, during this fifty days' residence in the tropics, was 31 cubic inches 

 (12*24 per cent.). In order to test whether this was due to climatic causes, 

 or resulted from custom in using the instrument, the same cases were again 

 tested about three weeks afterwards, on return to England in September, 

 when it was found (column 4) that the capacity of the chest for air had 

 again decreased in every case by an average of 26 cubic inches. Although 

 the temperatures were identical (65° F., shade) on quitting and returning to 

 England, the time was apparently too short to allow the capacity of the 

 lungs to resume their first standard average of 256 cubic inches, being still 

 at 260 cubic inches. But this result followed a subsequent reduction of 

 temperature to 42° F. (shade) in February 18/0, when the average capacity 

 of eleven of the same cases was found to be 253 cubic inches, that is, 3 cubic 

 inches below the first trial. This fact, however, goes far to prove that there 

 is a limit to this reduction in the pneumatic capacity of the chest in health, 

 which was probably nearly reached. Tbe results among the other adults 

 were identical, and showed that the capacity of the chest for air is con- 

 siderably greater in the tropics than in temperate climates. This was 

 noticeable in five of the six cadets. During the three weeks of the return 

 voyage between the tropics and England, when from faulty diet their growth 

 was nearly or altogether stopped, the capacity of the chest decreased con- 

 siderably, when it might have been reasonably expected that the diminished 

 capacity from climatic causes would have been more than counterbalanced 

 by expansion from growth, usually very rapid at that age. This actually 

 occurred in the sixth (Lees), a tall growing youth, in whom an increase of 

 27 cubic inches showed that his chest had enlarged considerably. The 

 greatest increase in the pneumatic capacity of the chest from this sojourn 

 in the tropics, of the twenty-four cases here recorded, amounted to 39 cubic 

 inches, and the lowest to 21. 



This and the subsequent experiments were made at sea, and in equable 

 super-oceanic temperatures *. It will be interesting to know whether the 

 same laws prevail in insular, littoral, and especially continental climates, 

 possessing a higher day, lower night, and greater diurnal and annual range 

 of the thermometer. 



* The daily mean range of temperature, Fahrenheit, was : — 



Highest. Lowest. Eange. 



Extra-tropical 9° 1° 3° -63 



Tropical 1° 2°'9 



the average for the entire voyage being 3° 2 F. 



