[ 4oi ] 
to the diftance of more than ± of his femi-diameter 
from his furface. 
Let philofophers confider, whether thefe indica- 
tions of the vaft height of the fun’s atmofphere 
give any degree of probability to a conjecture of Sir 
Ifaac Newton’s, that the diflipation of the fun’s 
fubftance, which might be expeded to enfue from 
his intenfe heat, may in great part be prevented by 
the prodigious preffure of the incumbent atmo- 
fphere. 
The height of the atmofphere of Venus is con- 
fiderably greater according to the obfervations of 
Mayer and Rohlius than they imagined. Rohlius 
follows Caffini in the eftimation of the fun’s apogee 
femi-diameter, which Caffini over rated by 3" 45 /,f/ . 
This quantity, therefore, is to be added to the height 
of Venus’s atmofphere (15,5) as hated by Rohlius; 
which makes the true height i9 // .2 5, that is above 
4 of the diameter of the planet. I cannot but re- 
fled with fome degree of national triumph on the 
great part that our own country may juftly claim in 
many of the m oft curious difcoveries in all parts of 
the world. Mr. Meyer generoufly confefles how 
much he flood indebted to Englifli artifts. You told 
me that it is your intention to prefent that curious 
traCt to the Royal Society. You may likewife com- 
municate this if you think it contains any thing wor- 
thy of their notice. 
I am, Sir, with great efteem, 
Your moft obedient 
and moft humble fervant. 
Broad- Street, 
Tune n, 1767. 
vol. lvii. 
Sam. Horfley. 
XXXIX. 
Fff 
