664 PHILOSOPHICAL T8ANSACTIONS, [aNNO 176Q. 



sufficiently. At Martihico, one of our missionaries observed the contacts at 



3h 15"! i4«, and 3*^ 33" 57'; when we have the longitude exact, this observation 



will also be of use. 



Here are some observations of the 1st satellite made at Gottingen, just 



received from Mr. Liunberg. 



J 1769 April 21 Im. l Sat. . IS*" '^r 37' Refractor of 14 feet. 



28 15 1+ 34 Ditto of 10 f of Liberkuhhn. 



30 9 43 21 The same. 



May 23 Em. 1 .... 12 6 31 



So far M. De Lalande. 



The Extract of M. Messier s Letter to M. Magalhaens is as follows: 

 : I observed the transit of Venus, June 3, 1769, at the college of Louis le 

 Grand at Paris, which is 2' to the east of the meridian of the Royal Observatory. 

 I had an achromatic telescope, of 12 feet focus, which had an aperture of 3|- 

 inches, and magnified 180 times, with the view of making my observation more 

 correspondent to that "which M. the Abbe Chappe was to make, in California, 

 with a telescope of the same length, the same magnifying power, and equal 

 goodness. The first contact could not be seen, on account of a very thick cloud; 

 there even fell some rain. I waited for the 2d; tlie sun then was pretty clear. 

 But there were some vapours, which caused such great undulations as to hinder 

 me from seeing the disk of the sun, and that of Venus, well defined. At 

 7*" 38"" 45' apparent time, or 7'' SS" 43' reduced to the meridian of the Royal 

 Observatory, the 2d contact appeared decisively to me. Two seconds after, a very 

 fine thread of light appeared between the limb of Venus and that of the sun; so 

 that in my observation there is not an uncertainty of 2 seconds in the moment 

 of the internal contact. After this observation, I viewed the sun with different 

 glasses, which rendered him alternately red and white. I saw Venus, with this 

 last colour, with a crescent of a bluish colour; and a little inclined towards the 

 limb of the sun: with the glass which made the image of the sun red this 

 crescent disappeared; but I saw Venus flattened in the direction of the crescent. 

 I measured the greatest and least diameter; the greatest was 56*^-, and the least 

 53"4-. Perhaps this crescent was only visible by the effect of some optic illusion ; 

 but I relate only what I saw. At 7** 52'" 8", apparent time, I measured the 

 interval between the limb of Venus and that of the sun, which I found 46"\i 

 and at 7^ 58"" 4», the first limb of Venus touched the horizon. 



By a letter from M. I'Abbe Bourriot to Mr. Magalhaens it appears, that 

 Messrs. de Fouchy and Bailly, at the Meute, each made use of reflecting 

 telescopes of 30 inches focus and 44- inches aperture; that M. Bory made use 

 of an achromatic telescope of 5 feet focus, and 2 inches aperture; and M. 

 I'Abbe Bourriot made use of a very good achromatic telescope of 6 feet long, 

 and 24- inches aperture, made by himself, magnifying 120 times. 



