L 3&7 1 
nous bodies, as the appulfe of the moon’s lucid limb 
to a ftar or planet. 
The expedition with which the author obferved 
his fecond phenomenon, is truly fomewhat extraor- 
dinary ; namely, that he fhould firfl: obferve what he 
names the final contact ; fecondly, that he fliould take 
away his green glafs; and then, thirdly, that he fhould 
be able fuddenly to alter the conformation of his 
eye, fo as to fee diftinctly with a much greater in- 
flux, of light, and then take another obfervation, and 
all in the fliort fpace of four feconds ! IVleAieurs 
Mairan and Bouguer take notice of this in their cer- 
tificate, which follows this memoir; and own, that 
his obfervations were fuch, as feem to have required 
the attention of feveral perfons. 
Upon the whole, we may conclude, that the fe- 
veral phenomena, obferved by this gentleman, in the 
tranfit and egrets of Mercury, were owing to in- 
difiinctnefs of vifion, arifing either from the eye, the 
telefcope, or the air ; and that this alone may' ac- 
count for them all, without having recourfe to flip- 
pofed circles of aberration; which can never pof- 
iitxly exift in a well-conflructed reflecting telefcope. 
L VI 
