gi8 — Prefident WiLLARD’s magnetical Obfervations, 
XT. Obfervations made at Beverly, Lat. 42° 36’ N. Eong.75° 
45 W. to determine the Variation of tbe magnetica? Needle. 
By the Rev. Josepu Wirt AR», Prefident of the Univerfity 
at Cambridge, V. Pref. A. A. 
A N attention to the variation of the magnetical needle, it 
is well known, is of great importance at fea, nor is it 
-of fmall confequence upon the land; efpecially in Norzh- 
America. From the firft fettlement of this country, the lines 
` between towns, and between lots of land appropriated to indi- 
viduals, have been determined by the magnetical needle. If 
"the variation always continued the fame, no difficulty would 
enfue, in again tracing the lines, upon the fame magnetical 
 Courfe ; but as it alters from time to time, the lines run in any 
fucceeding years muft deviate from the firít, and from one an- 
other, unlefs proper allowances are made for the alteration. 
From the want of a fufficient number of obfervations, and of 
: attention to this fubje&, in thofe who have furveyed the lands 
in this country, difficulties have arifen at one time and another, 
* between towns and individuals. To remedy this inconvenience 
: for the future, this Academy, fome time ago, recommended 
i magnetical obfervations, to determine the variation, which it is 
‘to be hoped will be made in various parts of the country, and 
-at proper intervals of time, and be uniformly attended to by 
s our farveyors. Since this recommendation, I have endeavour- 
ced to determine the variation at Beverly, with as much exact- 
snefsas I was able. With this view, I procured an azimuth 
scompals, of Dr. Gowin. Knight's invention. It appears to be 
TM good 
