ws 
262 Mr. Herscuer’s Odfervations 
generally gibbous, ‘and its oppofitions are fo fearee, and of 8 
fhort a duration, that in more than two years time we have 
not above three or four weeks for fuch obfervations.  Befides, 
aftronomers being already ufed to fee this planet generally 
diftorted, the {pheroidical form might eafily be overlooked. 
Objervations relating to the polar flattening of Mars. 
1783, Sept 25. gh. 50’. I can plainly fee that the equatorial 
diameter of Mars is longer than the polar. Meafure 
of the equatorial diameter 21” §3’”; of the polar 
diameter 21” 15’ full meafure, that 1s, certainly not 
too fmall. The wires were fet as outward tangents 
to the difk, and the zero, as well as the meafures, 
were taken by the light of Mars. 
Sept. 28. 14h. 25’. I fhewed the difference ‘of/the 
polar and equatorial diameters of Mars to Mr. Wi1- 
son, Affiftant Profeflor of Aftronomy at Glafgow. 
He faw it perfectly well, fo as to be entirely con- 
vinced it was not owing to any defect or diftortion 
occafioned by the eye lens; and, becaufe I withed 
him to be fatisfied of the reality of the appearance, 
while he was obferving, I reminded him of feveral 
well known precautions; fuch as caufing the planet 
to pafs dire&tly through the center of the field of 
view, and judging of its figure at the time when it 
was mott diftinct and beft defined, and fo forth, 
Sept. 29. I fhewed the difference of the polar and equa- 
torial diameters of Mars to Dr. BLacpren and Mr. 
AuserT. Dr, BLAGDEN not only faw it imme- 
diately, 

