DAILY ROUTINE AND BODY TEMPERATURE. 247 
well seen on June 24, 25, and 26, when the external temperature was high and muscular 
movement only slightly more active than on the four preceding days. It shows what 
a powerful influence even very moderate exercise has on the body temperature in hot 
weather. On the 24th at 3 p.m. the rectal temperature reached 38°°5 C., and at 7 a.m. 
the following day it was 36°°7 C., giving a range of almost 2° C., about double the 
average for the previous five days. 
After getting to sea on the homeward journey cold, foggy, depressing weather, such 
as is usually found on the banks of Newfoundland, was experienced for the first four 
days, and its influence is at once evident on the temperature curve. The maximum 
falls about 1° C. between the 26th and 27th, and the diurnal range is also greatly 
reduced. The lowest point was reached at 3 a.m. on September 30, when the rectal 
thermometer stood at 36°°2. From June 30 till the end of the voyage the weather was 
clear, bright, and warm, with sunshine throughout the greater part of the day, and here 
again the effect on the body temperature is at once visible. 
The influence of severe muscular exercise with a moderate external temperature is 
well seen on August 5, when a long walk was taken over rough ground; the rectal 
temperature was maintained over 38° C. for several hours, while the air temperature 
averaged about 11° C., with a cool breeze blowing. Again the influence of a high air 
temperature with moderate muscular exercise is illustrated by the rectal temperature 
curves of August 22, 23, and 24. On the 22nd the ship was in the lower reaches of 
the Gulf of St Lawrence, just through the Straits of Belle Isle, and not far from ice. 
As she steamed up the Gulf and into the river the air temperature rose rapidly until 
it reached the neighbourhood of 31° C. near Montreal on the 24th. 
On the train sleep was poor, and the minimal rectal readings were high on August 
26 and 27, probably on this account, while the effect of a sound sleep following a 
period of fatigue is seen on the morning of the 28th, when at 3 o'clock the body 
temperature (rectal) sank to 36°°7 C., a point lower than had been reached on any 
previous occasion during the westward journey with one exception, 4 a.m. August 17. 
The contrast between the curves of August 5 and 29 shows the effect of muscular 
exercise, the external temperature being not much different on the two occasions. 
Proceeding now to the discussion of the main question (to throw some fresh light 
on which the present investigation was undertaken), viz. whether the temperature curve 
is controlled by purely local and external conditions, or shows evidence of an innate 
periodicity independent of these, I believe that we shall find the evidence to be mostly 
on the one side. If the temperature rhythm were fixed in the observer's body we 
should expect to find that as he proceeded eastward, gaining time daily, the morning 
(6 to 9) rise would begin later and later each successive day until the end of the journey, 
and when Edinburgh was reached, where 11 a.m. corresponds with 6 a.m. at Ithaca, this 
tise should show itself between 11 a.m. and 2 p.m. In this relation we shall consider 
the rectal temperature only, since this is influenced to a smaller degree by accidental 
external disturbances than either the buccal or axillary temperature. A careful 
TRANS. ROY. SOC. EDIN., VOL, XLVIII, PART II. (NO, 12). 38 
