5.26 Dr. Rattray on the effects of Change of Climate [June 16,- 



The following Table shows, first, that the average pulse for the tropics 

 (87^) is lower by 2^ beats than that for the temperate zone (90), indicating 

 a more languid circulation ; second, that the same holds good for the 

 average morning and evening pulse ; third, that the average afternoon 

 pulse is higher in the tropics than in temperate latitudes, probably from 

 solar heat, greatest at that period of the day ; fourth, that the highest and 

 lowest pulse of the period occurs in the morning ; fifth, that the morning 

 pulse has the greatest, and the evening the lowest range. 



Table VIII. — To contrast the tropical and temperate pulse &c. 





Number of 





Tropics. 





Temperate 





observations. 



Lowest. 



Highest. 



Kange. 



Average. 



zone average. 



9 A.M 



53 



66 



112 



46 



864 



917 



3 P.M 



53 



68 



108 



42 



88-8 



88-1 



9 P.M 



49 



73 



110 



37 



873 



90-5 













87-5 



901 



The reduction of the pulse in the tropics is doubtless related to the 

 diminished respiratory function ; and further observation may prove what 

 the latter fact suggests, viz. that the pulse is diminished not only in fre- 

 quency but in force*. The rise in the pulse towards afternoon and its 

 subsequent fall are doubtless physiologically connected with a correspond- 

 ing rise and fall in the temperature of the body at the same periods 

 (Table IX.). The relation, however, does not extend to the volume or 

 number of the respirations, the former being nearly alike during these 

 three periods of the day, and the latter greatest towards night. As these 

 observations, however, on the most excitable of all organs, the pulse, were 

 made on one individual only, and at sea, where motion of the ship, weather, 

 Sec. render it impossible to eusure day by day the identical conditions 

 necessary to give completely satisfactory results, their confirmation is 

 necessary. 



III. The Influence of Tropical Climates on the Temperature of the Body. 



In this inquiry, so intimately connected with the two previous ones, viz. 

 the respiration and circulation, the facts were ascertained by placing an 

 ordinary Fahrenheit thermometer under the tongue thrice a day, during 

 the same voyage as last, the temperature of the air in the shade on the 

 verge of the tropics being 72° F., at the equator 84° F., and the average 

 of the tropics generally 76*9 ; and the atmospheric humidity represented 

 by a difference between the wet and dry bulbs of a Mason's hygrometer of 

 0° to 7\°, the average being 3°'8 F. 



* Parkes (' Practical Hygiene ') avers that the pulse is quicker in the tropics, though 

 perhaps not so full. In animals moderate heat does not, but great heat does quicken 

 the pulse. The latter, however, is evidently an unnatural temperature. 



