[ 171 3 
„ the Day or Night from the above Inftruments and a 
good Watch, I hope we fhould be able to obferve the 
Eclipfes of the firft Satellite of Jupiter, or any other 
‘Phenomenon of the like Kind, and thereby find the 
Diftance of Meridians, or Longitude at Sea. 
" The Variation of the Magnetical Needle, or Sea- 
Compafs, obferved by me at Churchill in 1725. (as 
in N° 393* of the Philofophical TranfaUions for the 
Months of March and April 1726.) was at that Time 
North 21 Degrees Wefterly, and this Winter I have 
carefully obferved it at the fame Place, and find it no 
more than 17 Degrees, fo that it has differed about 
One Degree in Four Years } for in 173 8. I obferved it 
here, and found its Declination 18 Degrees Wefterly. 
I have carefully obferved, and made proper Allow- 
ance for the Suns Declination and Refra&ion, and 
find the Latitude here to be 5 8 Degrees 5 6 Minutes 
North : But in moft Parts of the World, where the 
Latitudes are fixed by Seamen, they are for the moft 
part falfly laid down, for want of having regard to 
the Variation of the Suns Declination, which, com- 
puted at a diftant Meridian, when the Sun is near the 
Equator, may make a great Error in the Suns riling 
and fetting Azimuths , &c. 
Thefe things I thought proper to take Notice of, 
as they may be of Service to Navigators, and the Cu- 
rious in Natural Inquiries. 
The foregoing Relation having been given by Capt. Middleton to 
the late worthy Prefident of the Royal Society, Sir Hans Sloane t 
Bart, he was pleafed to communicate the fame to the Society, and 
at the fame time, as the furviving Truftee of the late Sir Godfrey Copley , 
to nominate Capt. Middleton to receive this Year the Prize Medal, 
given annually by the Royal Society, in Confequence of Sir God- 
freys Benefaction ; and the fame was accordingly prefented to the 
Captain on St. Andrews Day lad, 1742. 
Z III. -The 
