22 ANNUAL OF SCIENTIFIC DISCOVERY. 



John Herschel, and Captain, now General Sabine ; on the French side, by 

 Colonel Bonne, and some of the most distinguished French engineer officers. 

 The plan adopted on this occasion, was to make simultaneous observations 

 on rocket-signals at a chain of stations extending from Greenwich to Paris- 

 In spite of all the care which had been taken in preparatory arrangements, 

 this enterprise, in a great measure, failed. On the English side, almost 

 every part was successful ; but, on the French side, nearly the whole labor 

 was lost, and the final result for difference of longitude depended only on the 

 observation of ten rocket-signals. 



Passing over the attempts made to verify the ancient survey, as well as 

 those made by private persons, to determine the difference of longitude by 

 the transmission of a few chronometers, AVC now come to the more fortunate 

 enterprise which has suggested the preceding-remarks. 



No sooner did there appear to be a reasonable prospect of success for the 

 submarine telegraph, than the astronomical authorities (the Astronomer 

 Royal, on the British side, and the Bureau des Longitudes, on the French 

 side) addressed themselves to the Submarine Telegraph Company, with a 

 view of establishing a connection by galvanic telegraph between the two ob- 

 servatories. By that company their applications were received in the most 

 liberal manner. The company's wires were placed at the service of the ob- 

 servatories at the hours most convenient for them ; the connections when 

 necessary were made by the company's officers, and no remuneration of 

 any kind was expected. 



It is not necessary here to go into details upon the method employed, 

 or the extent to which it was carried. It will suffice to say that several 

 thousand signals were interchanged ; so man}-, in fact, as to permit of the 

 rejection of the larger portion, retaining only those to the number of 

 nearly two thousand which were considered to be made under unexcep- 

 tionable circumstances. The contrast of this number with that of the signals 

 on which the determination of 1835 depended, is striking. But the difference 

 in the quality of the individual signals is not less striking. The result of a 

 single signal, given by the galvanic telegraph, is perhaps as accurate as the 

 mean of all the results of the former operation. It is unnecessary, therefore, to 

 say that no comparison can be made between the difference of longitude con- 

 cluded from the former observations, and that found from the mass of the 

 late signals. The former determination is now shown to be erroneous by 

 almost a second of time a large quantity in astronomy and this cor- 

 rection is nearly certain to its hundredth part. For this gain of accuracy, 

 this veritable advance of science, we are indebted, in the first instance, to 

 the power of commercial association of which we have spoken. 



The power, however, would have availed little if the possessors of it had 

 not been willing to allow it to be used for the benefit of society in the precise 

 way which the professional men indicated ; and it is most honorable to our 

 great commercial bodies that they have practically shown so much readiness 

 to aid in enterprises of scientific character, that accredited men of science 

 feel no difficulty in asking their assistance. 



We may congratulate the world on the growing tendency towards a closer 



