Contents xxix 



PAGE 



Conclusion : Considering only my own observations, the 

 final result of the experiments made with my steam calorimeter 

 is that the calorific value of a sheaf of the sun's rays, having 

 a section of one square metre, is at least 9698 gram-degrees 

 Centigrade per minute at the terrestrial sea-level ; and it is 

 certain that heat can be obtained from them there at this 

 rate and in a useful form by mechanical appliances of simple 

 construction. 



No. 12. THE TOTAL SOLAR ECLIPSE OF AUGUST 30, 1905. (From 



Nature, December 21, 1905, Vol. LXXlll, p. 173.) . . . 399 



As this eclipse was to be visible in an easily accessible 

 part of Europe, where the probability of finding fine weather 

 was great and the calculated duration of totality was nearly 

 four minutes, I determined to see it. A considerable display 

 of protuberances was expected and I wished to form my own 

 idea of their size by personally checking their persistence or 

 non-persistence through the phase of totality as seen from a 

 station situated as nearly as possible on the line of mid- 

 totality. The display of protuberances at the moment of 

 second contact was very brilliant ; when the time of mid- 

 totality arrived not a trace of them was visible to the naked 

 eye. Therefore these very brilliant protuberances had an 

 apparent height less than 45 seconds of arc .... 400 



This eclipse is compared with that of May 17, 1882, which 

 was observed at Sohag on the Nile ..... 401 



No. 13. ECLIPSE PREDICTIONS. (From Nature, October 19, 1905, 



Vol. LXXII, p. 603.) 402 



The predictions respecting the solar eclipse of August 30, 

 1905, as issued by the British Nautical Almanac and by the 

 French Connaissance des Temps are compared, and their 

 want of agreement is illustrated by a Table. The most 

 striking discrepancy between the two predictions is shown by 

 the width of the band of totality in Spain and the adjacent 

 Mediterranean, which is given as from ten to eleven nautical 

 miles greater by the French than by the British prediction . 403 



The astronomical data on which these predictions were 

 founded differed only in the accepted values of the apparent 

 diameter of the moon, but the grounds on which the British 

 and French authorities differed on this point have not been 

 made public, so far as I know. 



