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TRANS^CTIOXS OF SECTION A. " 673 



The following Papers were read : — 



1. On the Application of the Electric Telegraph to the Furtherance of 

 Eclipse Research. By Professor David P. Todd, Director of the 

 Observatory of Amherst College, U.S.A. 



In 1878 the idea first occurred to the writer' of telegraphing' eastward in 

 advance of the lunar shadow in order to euahle the immediate verification of 

 any possible discovery as of an intramercurian planet without waiting for another 

 eclipse to take placo. A scheme of application to the eclipse of 1887 was 

 published,'-' but the feasibility of the method was not demonstrated till the eclipse 

 of January 1889, when the California observations were, by tlie courtesy of the 

 Western Union Telegraph Company, reported in New York with such celerity as 

 to outstrip completely the motion of the moon's shadow across the earth.^ A like 

 experiment, only in more practical form, was carried out during the recent eclipse 

 by co-operation with Mr. A. E. Douglass, of the Lowell Observatory, whose station 

 was in Washington, Georgia. Totality there preceded the same phenomenon in 

 Tripoli, the writer's station, by 2 hours 45 minutes. Immediately totality was 

 over, Mr. Douglass reported in full the success of his observations and the instru- 

 ments with which they were made, his despatch being forwarded at once to 

 Washington and New York, and over the Western Union Company's cables to 

 Penzance. By the courtesy of J. Denison Pender, Esq., Vice-President and 

 Managing Director of the Eastern Telegraph Company, London, the messao-e was 

 forwarded over this company's cables from Penzance to Gibraltar, thence to'"lMalta 

 and finally to Tripoli, where a special messenger delivered it at once to the writer at 

 the British Consulate. This message was received and read in less than half an 

 hour of absolute time from its leaving Georgia, and more than two hours before 

 totality actually came on at Tripoli. Had the message announced any discovery 

 there was abundant time to have prepared for its special verification. ' 



The thanks of astronomers are especially due to the manao-ers of these 

 two great telegraph systems for their generous gift of this service, wliich has now 

 ])roved conclusively the practicability of communication between remote eclipse 

 stations while the moon's shadow is still upon the earth. It is easy to see how 

 such communication, during the total eclipse of 188'.i, might have atl'orded data for 

 the orbit of the comet discovered duiing that eclipse, and whose path is now 

 unknown. 



Similarly, also, application of the land and cable lines of the globe may be of 

 the greatest service in notifying the occurrence of future meteoric showers. 



2. On the Operation of Eclipse Instruments Automatically. By Professor 

 David P. Todd, Director of the Observatory of Amherst College, U.S.A. 



The successful application of automatic machinery to a wide variety of n«e8 

 and purposes, removing the uncertainty of manual operations, indicates clearly the 

 desirability of its application to the photography of solar eclipses. 



Three distinct systems of controlling the mechanical movements of such 

 instruments are feasible, the capabilities of all of which I have tested vrithin 

 recent years : 



(a) The pneumatic system devised and built for the U.S. Eclinse E\n-jdiiinn 

 West Africa, 1889.' ' 



The power requisite for the individual movements of shutters and plate- 

 holders was obtained by small collapsible pneumatic ' jjockets,' connected uit'h a 



' Washington AUrmomirat Oyscri-atidnsfdr ig/fi, Appendix iii, p. 3j J 



- American Journol of Science, vol. c.x.xxiii. p. 22G. 



' ^*^^^^%s*5 ''/ ^^ Sun, by Mrs. Todd (tJamp'So'n Low, :Jarston, k Co., ISOO) 



* Mtintniy mi^ide's E.A.&., vol. 1. p. 380. 



