OP ARTS AND SCIENCES. 359 



Intbstioations on Light and Heat, made and published wholly or ia part with appropriation 

 from the llmiFORD Fund. 



XIX. 



ON THE USE OF THE ELECTRIC TELEGRAPH DURING 

 TOTAL SOLAR ECLIPSES. 



By D. p. Todd, M.A. 



Presented January 12, 1881. 



One of the most intractable considerations in the study of the sun 

 and its surroundings lies in the small amount of time which is avail- 

 able for the prosecution of that study. Most of the phenomena in 

 the neighborhood of the sun can be investigated only vehen the sun 

 itself is hidden during eclipse. If we suppose a single observer to be 

 prepared for the observation of all the total solar eclipses of a cen- 

 tury, we shall find that the entire amount of time during which he may 

 contemplate the totally eclipsed sun will not differ much from an hour. 

 We may be sure, then, of the expediency of any scheme whereby 

 the rare moments of these eclipses may be utilized to their utmost 

 extent. K such scheme is devised, two important results are like to 

 follow : — 



(1) Economy of the sum-total of energy in any particular line of 

 solar research. 



(2) A consequent enlargement of the means of research in other 

 directions. 



The general conception of the scheme proposed in this paper may 

 be very briefly stated : Suppose a station to the east and a station to 

 the west on the line of any total eclipse, as widely separate as practi- 

 cable, and equipped for similar observations of discovery during the 

 progress of the eclipse : the method proposes the electro-telegraphic 

 transmission of important observations made at the western station to 

 observers at the eastern station, with due speed for their verification 

 or rejection when the lunar shadow reaches the latter station. 



For illustration, consider the next total eclipse, — that of 1882, 

 May 16. In detail, the particular advantages in connection with this 

 eclipse seem to be about these : — 



