246 Mr. Herscuen’s Odfervations 
far removed from the north pole.as.to fall a few degrees within 
the enlightened part of the difk, to become vifible to us. 
The fouth pole of Mars could not be many degrees from the ‘1 
center of the large bright fouthern {pot ef the year 1781, 
whofe courfeis traced um fig. 27 5 though the {pot was of fuch 
magnitude as to cover all the polar regions farther than 4 
7oth or 65th degree, and in that part which was on the meri 
dian July 3, at 10h. 54’, perhapsa little farther... : 
In the next. divifion of our fubjeét will be thewn, that thd 
inclination and pofition of the axis of Mars are fuch, that the 
whole circle, fig. 28. (which will appear to be an about 81° 52" 
of fouth latitude on the globe of Mars) was in view all the 
‘time the obfervations on the bright fouth polar fpot-of the year 
1783, which are marked upon it, were made, but in fo oblique 
a fituation as to be projected into a very narrow €Ellipfis. See 
fig. 24. where mz isthe little ellipfis in which the fpot @ 
revolved about the pole. Hence then we may eafily account 
for the obferved magnitude and brightnefs of the {pot O&. 23, 
24, and 27. when it was expofed to us in its snerjdian fplen- 
dour. Its fituations O&. 16. and 17..0n one extreme of the 
parallel, as well as thofe of O&. 5. and Nov. 4. on the other, 
gave us alfo a bright view of it: and, when we pafs over to 
that half of the circle which lies: beyond ‘the potes:the much 
greater obliquity into which the fpot muft there be projeted 
will perfedtly account for its being {maller at 13h. 7 of OG 
7. than lat 7 +h, 47’ of the fame evening. It will alfo expla 
its {mallnefs O&.4. and its increafe O&. 9. We-thall have 
occafion hereafter to recur to the fame figure, fo that I takeno 
notice at. prefent of the ee of pofition — are re marked | 
upon it. LX 
2 : Of — 
