PHYSICAL ann LITERARY. 173 
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Art. IV. 
' Of the Caufe of the Variation of the Obliquity 
of the Ecliptic, by Cov1n M‘Laurin, late 
- Fellow of the Royal Society, aud Profeffor of 
_ Mathematics in the Univerfity of Edinburgh. 
: r J \ HE French aftronomers in Peru, and 
4 4 Dr Bevis at London, and others elfe- 
_ where, have endeavoured to determine the 
4 obliquity of the ecliptic with greater accu- 
_ racy than former aftronomers had attained to. 
q The refult of their obfervations makes it to 
be now about 23° 29'28"t. It had been for 
fome time reckoned 23° 29’ 29”; and before 
that, 23° 2930”; and, by fome antient aftro- 
els, 19 or 20 minutes greater. Meff. Ca/- 
i and Bradley had found it to vary a little: 
\d this has given occafion to a notion, that 
is decreafing continually; that there was a 
time when the axis of the earth lay in the 
plane of the earth’s orbit; that it has been 
radually rifing, till now it contains an angle 
ith this plane of 66° 30’ 31”2; and that, in 
5: a 
