{ i6 4 ] 
XXIII, An Account of a remarkable Ap- 
pearance in the Moon , April 22, 1751, by 
James Short, F. R. 
Read April 25.YN Numb. 396 of the Philofoph. Trnnf. 
,7S, ‘ JL there is an account of an obfervation 
made on a particular and uncommon appearance of 
the lunar fpot called Plato in the nomenclature of 
Riccioli’s and Grimaldi’s Selenography , and Lacus 
nlger major in that of Hevelius. Signor Bianchini, 
to whom we owe this communication, fays, that it 
was the 16 of Auguft 1725, N. St. about an hour 
after fun-fet, when he took his obfervation with a 
dioptric telefcope, of the length of 150 Roman 
palms (about no Englifh feet) made by the famous 
Campani, the air being very ferene, and the moon 
(as he fays, fpeaking of the fame phenomenon in his 
book of Venus) a day pad: the firft quarter : fo that 
the faid fpot then lay in the common fedlion of light 
and darknefs. The mountainous oval margin, with 
which it is furrounded, was brightly illumin’d with 
the fun’s rays j but the plain bottom look’d darkifh 
as having not yet received his light. There was 
however extended along its area, from end to end, 
a track of reddifh light, as though a beam had been 
admitted through fome perforation in that fide of the 
margin, which was then expofed to the fun. M. 
Bianchini propofes the folution of this matter in two 
different ways : firff, by fuppofing an aperture in the 
margin, as juft now mentioned : or, fecondly, by con- 
ceiving the moon to have an atmolphere, and that 
thereby 
