on the Rotation of the Planets , &c. rz§ 
June 15. Clock if too (low. ph. 45'. The fame figure is 
upon Mars that was there May 9. at nh. T; but it is more 
advanced. I fuppofe it to be the fame, and in the fame fitua- 
tion, as April 17, 1777, at 7 h. 50'* 
June 17. Clock 20'' flow* 
9 h. 12'. The dark fpot on Mars is rather more advanced 
than it was May nth, at xoh. 18b 
I oh. The fpot is vifibly advanced: I fuppofe it will take 
near an hour to come to the center. 
10 h. if A very thick fog obfcures the fky. 
11 h. 15'. The fame darknefs. 
June 19. Clock 22" too flow by the tranfit of 0 Scorpii ob- 
ferved this evening. 
8 h. 40b The figure on the difk of Mars appears now to be 
as it was April 26, 1777, at 9 h. f fee fig. 18. 
I I h. 30b The figure of May 1 1. which I have been hitherto 
watching, is not come to the pofition it was then at 1 1 h. 43', 
but cannot be far from it. I fear, as Mars approaches the hori- 
zon, I ftiall not be able to follow him till the figure comes to 
the center, 
1 1 h. 47'.. The ftate of the air near the horizon is very unfa- 
vourable, With much difficulty I can but juft fee that the 
figure is not quite fo far advanced as . it was May nth, at 
1 1 h. 43', but can certainly not be above two or three minutes 
from it. 
n h. 51b The undulation of the air prevents all further 
obfervation. 
Let us now examine the refu It of the above mentioned obfer- 
vations : comparing together the two following fhort intervals 
of the year 1779, we have, 
Vot. LXXL 
S 
From 
