waiting before the Royal Society, the 2 1 March 1666. by Mf« 
Book, as follows ; 
Having a great defire(faith he) to obferve the Z?ody of Mars , 
whilft Acrenycal and Retrograde ( having formerly with a Glafs 
of about 1 2. foot long, oblervM fome kind of Spots in the Face 
of it, ) though it be not at prefent in the Perihelmm of its Orbe, 
but nearer its Apbehum , yet 1 found, that the Face of it, when 
neer its Oppofition to the Sun ( with a Charge, the 36. foot* 
glafs, I made ufe off, would well bear ) appear'd very near as 
big, as that of the Moon to the naked eye 5 which I found, by 
comparing it with the Full Moon , near adjoyning to it* 
March 10, 
But fuch had been the ill difpofition of the Air for feveral 
nights, that from more than 20. Obfervations ofit, which I had 
made fince its being Retrograde, I could find nothing of fatis- 
fadtion, though I often imagin'd, Ifaw Spots, yet the 
veins of the Air ( if I may fo call thole parts, which, being inter- 
fpers’d up and down in it, have a greater or lels Refractive 
power, than the Air next adjoyning , with which they are 
mixt) did make it fo confus’d and glaring, that I could not 
conclude upon any thing. 
On the third of March) though the Air were (fill bad enough 
yet I could fee now and then the Body of Mars appearing of 
the form A: which I prefently described by a Schemes and 
about io* minutes after, as exaCMy reprefenting what I faw 
through the Glafs, as I could, I drew the Scheme B. This I was 
fufficiently fatisfied ( by very often obferving it through the 
Tube, and changing my Eye into various pofitions, thatfo 
there might be no kind of Fallacy in it J could be nothing elfe, 
but fome more Dusky and Spotted parts of the Face of this 
Planet. 
March id. finding the Air very bad, I made ufe of a very 
{hallow Eye- glafs, as finding nothing Di /l in B with the greater 
Charge ; and faw the appearance of it as in C, which I imagin’d, 
might be the Reprefentation of the former Spots by a iefier 
charge. About g of the Clock the fame morning’, the Air be-, 
ing very had ( though to appearance exceeding clear , andcau- 
fing all the Stars to twinckle,and the minute Stars to appear ve- 
ry thick ) the Body feenvd like D » which I Rill fuppos’d £0 be 
