NA TURE 



{June 25, 1874 



LE GENTILS OBSERVATION OF THE 

 TRANSIT OF VENUS 



AS all the world is now thinking of the transit of Venus, 

 an episode of old time in connection therewith should 

 be very interesting. 



In a series of articles by M. W. de Fonvielle in La 

 Nature, from which the accompanying illustration is 

 taken, some interesting facts are given concerning Le 

 Gentil's observations of the transit of Venus in the open 

 sea about the middle of last century. These we reproduce 

 here with some supplementary information from Le 

 Gentil's own interesting work referred to below. His 

 voyages extended altogether from 1760 to 1771. They 

 consequently commenced before the transit of 1761, and 

 were continued after that of 1 769. 



The expeditions of Le Gentil, the account of which, 

 published by the royal press, fills two magnificent volumes, 



have left an ineffaceable mark upon the history of astro- 

 nomy. His work is a proof that a man of energy and 

 perseverance who sets himself to the solution of a great 

 and beautiful problem can find, in spite of all obstacles, 

 the means of immortalising himself. Posterity certainly 

 owes some indemnification to the indefatigable astronomer, 

 since his determination to solve scientific questions was 

 undoubtedly prejudicial to his interests, and even to 

 his love-affairs. 



A pupil of De I'Isle, Le Gentil was intended for the 

 church by his family, whose home was at Coutances, where 

 he was born Sept. 12, 1725 ; but his attachment to MUe. 

 Potier, belonging to one of the richest families of Cotentin, 

 made him give up all idea of so very celestial a profession. 

 A happy marriage, contracted in 1771, after eleven years 

 of absence, enabled him to triumph over his enemies, who 

 had taken advantage of his Ijcing far away to fill up 

 his place in the Academy of Science, and against his 



relations, who had attempted to take possession of his 

 property ; he had to go to law to make them give up what 

 they had taken. His death, which had been announced 

 so ofien, was very nearly becoming a reality, for he 

 was sei;!ed by a dangerous malady, which would have 

 carried him off but for the affectionate care of his wife. 



The Due de la Vrillicre, Minister of .State, entrusted 

 with the distribution of Icttrcs de cachet, was then Direc- 

 tor of the Academy. Le Gentil, having received from his 

 bureau the orders of the King, embarked in 1760 for the 

 Isle of France, on board the Berryer, a vessel of the 

 Indian Company, which carried fifty guns, and sailed in 

 company of the C('«/A-rt'V;//o/.f of sixty-four. On July 10 he 

 arrived at the Isle of France. Le Gentil resolved to pro- 

 ceed tj Rodriguez, where he did not know that Canon 

 Pingrc^, who had left Paris after him, had arrived, to exe- 

 cute a mission which he had received from the Academy. 

 The two astronomers woidd have unexpectedly met on 

 that island, then almost a desert, if Le Gentil had not 



found at th3 Isle of France the Sylphide, a frigate sent 

 to the help of Pondicherry, Le Gentd's original destina- 

 tion. Me, full of ardour, did not hesitate to embark on 

 board of this vessel. But the winds were adverse to 

 the expedition, and the Sy'phiJe wandered from March 

 25, 1761, to May 24, the sport of calms and of the irregular 

 winds of the north-east monsoon. On May 24, when off 

 the coast of Malabar, Le Gentil learned that Pondicherry 

 had been taken by the English. It was then necessary to 

 return to the Isle of France, where the Sylphide arrived 

 only on June 23, after having touched at Point de Galle 

 on May 30. 



It was between these two stations that Le Gentil ob- 

 served the transit of Venus, of which the following is his 

 description, stripped of all extraneous details : — 



■'To observe the entry of \'enu5 I employed an excel- 

 lent objective of 15 ft. (I'rench) focus, fixed to a tube 

 composed of four pme plinks which I h.xd made suffi- 

 ciently solid without being too heavy. To work it I got a 



