58 Mr Buchanan, On a solar Calorimeter used in Egypt 



visible radiating area of the sun and when at last this area is 

 halved in one second and becomes nothing in the next, the effect 

 which this sudden extinction of the sun produces, is a very 

 profound one. And this not on man only, but also on the beasts. 

 There were some turkeys in the camp, and they went about 

 as usual until the final phase above indicated began, when they 

 showed every symptom of alarm. When the sun reappears his 

 light increases as rapidly as it disappeared, and five minutes after 

 totality all interest in the eclipse has gone. What struck me 

 most besides the comet, were two so-called protuberances. I say 

 so-called because to the naked eye they look much more like in- 

 dentations or notches in the moon's disc and coloured red. This 

 is a subjective effect and due to the same cause as the " black 

 drop " in the case of the transit of Venus. 



Of all the natural phenomena which I have had the oppor- 

 tunity of witnessing there is none which produces so powerful an 

 impression as a total eclipse of the sun. In connection with this 

 it may be recalled that the eclipse of 17 th May, 1882, repeats 

 itself after 19 years on the 17th May, 1901, with this important 

 advantage, that in place of seventy seconds the maximum duration 

 of totality will be six minutes and a half, and it will occur very 

 nearly at noon at stations in Sumatra and Borneo. 



The 18th May was the hottest day experienced. Perfect 

 calm reigned until 2 p.m. when a breeze began to blow up the 

 Nile and continued throughout the afternoon although it was 

 never very strong. During this forenoon the maximum results 

 were obtained with the calorimeter and the temperature of the air 

 reached its maximum 105° F. at 2 p.m. It will be noticed that 

 the temperature of the wet bulb thermometer was only 65°, or 

 40° F. below the dry bulb ; the air was of extraordinary dryness. 

 One effect of a climate such as this where great dryness is 

 associated with very high temperature, is that, although perspira- 

 tion is abundant, the skin is never moist, indeed it is so dry that 

 it has a tendency to crack. Another remarkable subjective effect 

 of high air temperatures such as those of the afternoon of the 

 18th is the notice given when the temperature of the air passes 

 from below that of the human body to above it. It is a matter 

 of common experience that in preparing a warm bath, very slight 

 differences of temperature can be appreciated by the hand when 

 the water is at, or about the temperature of the human body. 

 With air the conditions are different ; the capacity for heat of all 

 the air that can at any moment touch exposed portions of the 

 body is very small and produces no noticeable effect. But al- 

 though it cannot do so directly it can do so vicariously for instance 

 through the metal rim of a pair of spectacles. The calorimetric 

 work described in this paper necessitated continuous exposure to 



