40i 



Biographical Account of 



Instructed by this unlucky experiment, he demanded if the 

 sector of La Caille had not the same fault: but instead of a 

 cylinder, La Caille had a very fine needle, which could hardly 

 occasion a greater error than He demanded, likewise, if 



the sector which our [the French] academicians had taken to the 

 polar circle in 1736 was not of the same construction ^ and his 

 conjecture was likewise just. But the dimensions of the cyhnder 

 being only half a line, the resulting errors must have been only 

 one-fourth part of those ascribed to the operation after it was 

 performed a second time by M. Svanberg with the repeating 

 circle. 



He w^as obliged to omit observations on the parallax of the 

 moon, as well as of Sirius. However, to go as far as possible 

 into the views of La Caille, he had recourse to the observation 

 of right ascensions. He was doubtless aware that this mode 

 could not come into competition with that of the French astro- 

 nomer; for he never mentioned the results which he obtained^ 

 though he repeated them a second time in his voyage to Barbadoes. 



If he had the regret of seeing all his projects prevented without 

 any fault of his own, he took care at least, after the example of 

 La Caille, to make his voyage useful by determining various lon- 

 gitudes. He tried different methods of resolving these problems; 

 and confirmed all the conclusions drawn by La Caille in favour 

 of the distances of the moon from the sun; and as he had in 

 his possession very accurate instruments, he ascertained that the 

 limits of error were very small. He gave new formulas for cal- 

 culating these observations, and carried his accuracy so far as to 

 calculate separately the effect of refraction and of parallax. 



On his return he published his British Marinp.r's Guides in 

 which he proposed that Great Britain should adopt the plan of a 

 nautical almanac traced by La Caille after his voyage to the Cape 

 of Good Hope. The same year he made a voyage to Barbadoes, 

 in order to examine the goodness of Harrison^s time-pieces. The 

 report Which he made at his return, though favourable in general 

 to the celebrated artist whose invention he had subjected to the 

 most severe test, was far from convincing Harrison, who attacked 

 liim in a pamphlet. Maskelyne wrote a reply to this attack. 

 Naval men and philosophers took part with one side or other, 

 according to their ideas and their habits. M. de Fleurieu, parti- 

 cularly connected with F. Berthoud, and entirely devoted to the 

 cause of the time-pieces, forgot perhaps on this occasion his 

 accustomed moderation. It was a dispute between tvvo useful 

 methods, calculated to assist each other. Maskelyne did not 

 find the time-pieces sufficiently certain, nor sufficiently regular. 

 Harrison affirmed, not without reason, that they w^ere within the 

 limits prescribed by Act of Parliament. He demanded the 

 whole reward, which was afterwards given him, though at first 



