the Reprefentatlonbf, the fame Spots through a more confuf- 
ed and glaring Air. . 
But obferving March 21. I was furprifed to find the Air 
( though not fo clear, as to the appearance of final! Stars ) fo 
eX 6 eedingtranfparent 9 and the Face o£Mars fo very well defined § 
and round, and diftindt, that I could mahifeftly fee it of the 
Ihapein E. about half an hour after Nine at night; The Tru 
angular fpot on the right fide ( as it was inverted by the Telef- 
cope, according to the appearances, through with all the pro- 
ceeding Figures are drawn ) appear'd very black and diftin^fc, 
the other towards the left more dim 5 but both of them fuffi- 
eientiy plain and defin’d. 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, as m,Fj which limagind 
to fhew me a Motion of the former triangular fpot : But defign- 
ing to obferve it again about 3. of the Clock the fame Morn- 
ing, I was hindred by cloudy weather. 
But March 22. about half an hour after 8. at night, finding 
the fame Spots in the fame pofture, I concluded, that the pro- 
ceeding Obfervation was only the appearance of the fame 
Spots at another height and thicknefs of the Air : And thought 
my felf confirm’d in this Opinion , by finding them in much 
the fame pofture, March 23. 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 fomething or other interven’d, 
that hindred me, till March 28. about 3 of the Clock, the Air 
being light (in weight) though moift and a little hazy ; when I 
plainly law it, to have the form, reprefented in 1 3 which is not 
reconciieabie with the other Appearances, unlefs we allow a 
Turbinated motion of Mars upon its Center : Which , if fuch 
there be, from the Obfervations made March 21. 22. and 23. 
we may guefs it to be once or twice in about 24. hours unlefs it 
may have fome kind of Librating motion ; which feems not fo 
likely. Now, whether certainly fo or not, I ihall endeavour, 
as oft as I have opportunity, further to obferve. 
A particular direction to the Figures mentioned in 
the precedent difeourfe. 
A. March 3 d - Oo b * 2C m - in the mmimg-jbe Air having many infiec 
K k 2 
tin g 
