Magnitude of the Georgium Sidus, &c. i q 
•J 
lures; which would be plus , when taken with a lucid dilk 
or ring ; and minus, when obtained from a dark ring 
or circle. Having fufpended a row of paffe-board circles 
again id an illuminated Iheet of oiled paper, I caufed the Geor- 
gium Sidus to pals by them feveral times, and feleffed from 
their number that to which the Planet bore the greateff refcm- 
blance in magnitude. I produced a perfect equality by fome 
fmail alteration of my diftance, and the refult was as follows : 
3> i6 S 
6 33>9S 
,0049925: hence 
22 
9".8_ /, 
'“4 > 53 * 
I was defirous of feeing what would be the cffeff of leffenino- 
the light of the illuminated frame, againlt which the dark 
diiks were fufpended, and alio waited a Ihort time that the Planet 
might rife up higher. The meafure being then repeated at a 
different diltance, and with a different black dilk, 1 obtained 
the following particulars : 
3 > s 9 1 1 s' 22 ',i n , 
— = ,0044704; and — = 4 ,06. 
I intend to purfue tliefe experiments ftill farther, efpecially 
in the time of the Planet’s oppofition, and am therefore un- 
willing as yet to draw a final conclufion from the feveral mea- 
fures. In a fubjeff of iuch delicacy we cannot have too many 
fluffs to regulate our judgement. Thus much, however, we 
may in general lurmife, that the diameter of the Georgium 
Sidus cannot well be much lefs, nor perhaps much larger, 
than about four feconds. From this, if we will anticipate 
more exaff calculations hereafter to be made, we may gather 
that the real diameter of that planet muff be between four and 
five times that of the earth : for by the calculations of M. de 
la lande, contained in a letter he has favoured me with, the 
diffance of the Georgium Sidus is ffated at 18,913, that of the 
earth 
