the Reprefentation of the fame Spots through a more confuf- 
ed and glaring Air. 
But obferving March 21. I was furprifed to find the Air 
f though not fo dear, as to the appearance of fraall Scars ) fo 
ex$eedingtranfparent^ and the Face oiMars lo very well defined^ 
and round, and dittind, that I could manifeftly fee it of the 
Chape in E. about half an hour after Nine at night. The Tru 
angular fpot on the right fide ( as it was inverted by the Telef- 
copc, according to the appearances, through with al! the pre- 
cecding Figures are drawn j appear'd very black and diftin^t/ 
the other towards th@ left more dim 3 but both of them fuffi- 
ciently plain and defind. About a quarter before 12. of the 
Clock the fame night, I obferv'd it again with the fame Glafs, 
and found the appearance exactly, asinF; which I imagine! 
to (hew me a Motion of the former triangular fpot : But defign- 
ing to obfcrve it agaia about 5. of the Clock the fame Morn- 
ing, I was hindred by cloudy weather. 
But March 21. about half an hour after 8, at night, finding 
the fame Spots in the fame pofturCj I concluded, that the pre- 
ceeding Obfervation was only the appearance of the fame 
Spots at another height and thickncfs of the Air : And thought 
ray felf confirm'd in this Opinion, by finding them in much 
the famepofture, Msirch 25. about half an hour after 9, though 
the Air was nothing fo good as before. 
And though I defired to make Obfervations, about 3. of the 
Clock thofe mornings ; yet foraething or other intervened, 
that hindred me, till AfarchiS. about 3 of the Clock, the Air 
being light (in weight) though m©ifl: and a Httle hazy • when I 
plainly law ic, tohavetheform, reprcfcntedinl^ which is not 
reconcileable with the other AppearanceSj unlefs weallow a 
Turbinated motion of Mars upon its Center : Which, if fuch 
there be, from the Obfervations made ^/^r^:/^ 21. 22. and 29. 
we ma.y guefs it to be ©ice or twice in about 24. hours unlefs it 
may have feme kind of LibraMgmotion ; which feeras not fo 
likely. Now, whether certainly fo or not, I (hall endeavour, 
as oft as 1 have opportunity, further to obferve. 
A particular diredlion to the Figures mentioned in 
the precedent difcourfe. 
A. March 3^' Oo^- 20"^* in the mornhioithe Air having many injlec- 
K k 2 ting 
