528 PHILOSOPHICAL TRANSACTIONS. [aNNO 1774. 



West of Royal 



f Place of observation on St. John's island 4" 11" 49'' 



Louisbourg 3 59 57 



South Point, entrance of Gasper 4 17 50 .. ^^u «. ^k^j^. 



The meridian of ^ Capt. Holland's house near Quebec 4 44 46 > Observatory, 



Kittery Point, province of Main, in Piscataqual „ .^ at Greenwich. 



harbour J 



_Portsmouth, New Hampshire 4 42 53 _ 



XXJ^. Immersions and Emersions of Jupiter sjirst Satellite, observed at Jupiter s 

 Inlet, on the Island of Anticosti, North America, by Mr. Thomas fVright, 

 Deputy Surveyor General of Lands for the Northern District of America; and 

 the Longitude of the Place, deduced from Comparison with Observations made 

 at the Royal Observatory at Greenwich, by the Astronomer Royal, p. IQO. 



These observations were made at Jupiter's inlet, 1 leagues to the westward of 

 the south-west point of the island of Anticosti, situated at the entrance of the 

 river St. Laurence, in latitude 49° 26' north, with a 2 -feet reflecting telescope 

 of the late Mr. Short's construction. Mr. Wright's observations of the eclipses 

 of Jupiter's first satellite, corrected, are as follow: 



Time at Greenw. per Naut. Almanac. Difference of meridians. 



50" 27' 19" 5" 29" 4" 15" 2' 



21 17 17 53 4 15 32 



15 34 14 4 15 14 



46 17 29 16 4 15 30 



59 16 25 27 4 14 28 



23 18 22 11 4 14 48 



19 12 51 l6.. 4 14 57 



56 14 47 48 4 14 52 



17 13 8 59 4 14 42 



The mean difference of meridians by the 4 immersions is 4*' 15™ 19-^% and 

 by the 5 emersions is 4*' 14"* 45-i-'; both which ought to be corrected, by the 

 help of the nearest observations made at the Royal Observatory at Greenwich. 

 The immersions and emersions observed there, proper to compare with the pre- 

 ceding observations, are these: all observed with a 6-feet reflector, which, I 

 reckon, shows an immersion of the first satellite 20' later, and an emersion of 

 the same as much sooner, than a 2-feet reflecting telescope. 



The correction of the Nautical Almanac for a 6-feet reflector, by the mean of 

 the 2 immersions, is — 43% which applied to 4*' IS"" 19i% the longitude of Ju- 

 piter's inlet found from immersions, by the help of the Nautical Almanac, gives 



