70 Mr Buchanan, On a solar Calorimeter used in Egypt 



The diagram Fig. 9 shows the progress of the eclipse and the 

 portions of the sun successively uncovered. 



From Table IV. we see that when distillation has begun, it in- 

 creases at a much greater rate than does the exposed sun's surface. 

 This must be so in the early stages, because we see that it is not 

 till 26 minutes after totality and when already 33 per cent, of the 

 sun's surface has been uncovered that the water in the boiler boils, 

 and it takes 16 minutes more before any distillate is collected. 

 Even when 50 per cent, of the sun is exposed the rate of distilla- 

 tion is only 0"4 c.c. per minute. After this more weight may be 

 attached to the observations, but their numerical significance is 

 not great. The experiment was not originally contemplated. The 

 instrument was constructed for use with the strongest uneclipsed 

 sun that could be found. Still it shows that useful information 

 could be obtained by arranging for making trustworthy observa- 

 tions during the progress of an eclipse. The provisions which it 

 would be necessary to make are instructive, because they indicate 

 some of the capabilities and defects of the instrument. 



Table IV. 



Apparent 

 Solar 

 Time, 



A.M. 



Cubic 

 centims. 

 col- 

 lected 



Mean date 



and 

 Interval, 



A.M. 



Minutes 



from 

 Totality 



Rate of 

 Distillation 



Amount 

 of Sun's 

 surface 

 exposed 



hr. min. sec. 



8 34 







hr. mm. sec. 







c.c. per min. 



o-ooo 



9 1 









27 





0-329 



9 17 















9 19 30 



1 



9 18 15 



44 



0-400 



0-509 



9 21 















9 29 30 



5 



9 25 15 



51 



0-589 



0-609 



9 36 5 



10 



9 32 47 



58-5 



0-759 



0-703 



9 40 55 



15 











9 45 45 



20 



9 40 55 



67 



1-034 



0-788 



9 47 















9 51 15 



5 











9 56 



10 



9 51 30 



77-5 



1-111 



0-864 



9 59 50 



15 











10 4 5 



20 



10 



86 



1-237 



0-924 



10 5 















10 8 52 



5 











10 14 35 



11 



10 9 45 



96 



1-146 



0-987 



10 18 40 



16 











10 22 20 



20 



10 18 30 



102-5 



1-161 



1-000 



