1870.] 



on the Human Economy. 



519 



Column 1 gives the average of the entire voyage, during which the 

 equator was crossed and again recrossecl. Here the results, morning, after- 

 noon, and evening, both in the tropics generally and in its warmest part, 

 the equatorial doldrums, are so very nearly identical that we may conclude 

 that period of the day has very little influence on the capacity of the chest 

 for air, or the power of taking deep inspirations. 



Closely allied to the foregoing is the influence of tropical climates on 

 the frequency of the respirations. In heated air-chambers respiration 

 becomes less in man*. Yierordt and Ludwig also found that the respira- 

 tions are lessened in number in animals subjected to heatf . Does this 

 occur in natural tropical climates ? We might infer that as the volume 

 inspired increases, so does the number of respirations. But fact (Table V.) 

 proves the reverse, and shows that, as in hot artificial climates, they are 

 diminished in number. 



Table V. — To show how the frequency of the respiration is affected by 



tropical climate. 



Temperate J England, in summer (June) 

 Zone. \ „ in winter (8 Feb.) 



f Equatorial doldrums (out- 



Tronics \ ward v0 ^ a » e ^ 



1 ""] Equatorial doldrums (return 



I voyage) 



Average 

 tempe- 

 rature 



(shade). 



Highest 

 number 

 of respi- 

 rations. 



Lowest 

 number 

 of respi- 

 rations. 



Average 

 number 

 of respi- 

 rations. 



Falir. 









62° 



18 



135 



15-68 



42-25 



175 



15 



165 



78-74 



14-5 



11 



12-74 



78-6 



15 



12 



1374 



This Table is compiled chiefly from the daily results of a three months' 

 voyage to Bahia and back, the observations being taken in the standing 

 posture at 9 a.m., 3 p.m., and 9 p.m. ; the averages are for a week. Thus 

 in the summer of England, with an average temperature of 62° F., the 

 average number of respirations per minute was 15| ; whereas in the dol- 

 drums, or warmest part of the tropics, during the outw T ard voyage, with a 

 temperature of 78|° F., the average was only 12|, and on the return 

 voyage 1 3-f, — a decided decrease. In the winter of England (February), 

 with a temperature of 42° F., the average had increased to 16 J, and at 

 freezing-point (32° F.) to 17|. With those results similar experiments 

 carried out at my request by a colleague J coincided, and showed that 

 though, as in temperate latitudes, the activity of the respiration differs in 

 different individuals, they are diminished in number in the tropics. Thus, 

 while his respirations averaged 16*077 per minute in the temperate climate 

 of England (January, average temperature 32° to 44° F.), they average 



* Parkes, 'Practical Hygiene ' ; Hooper, 4 Physicians' Vade Mecum,' &Ci 

 t Parkes, ibid. 

 . $ Mr. T H» Knott* Assiatant-Sui'gemli 



