m the Rotation of the Planets , Sec. tty 
June 15. Clock if' too flow, 9 h. 45k The fame figure is 
upon Mars that was there May 9. at 1 1 h. 1 ' ; but it is more 
advanced. I fuppofe it to be the fame, and in the fame fitua- 
tion, as April 17, 1 777 ^ at 7 la. 50 k 
June 17. Clock 2o v flow. 
9 h. 12'. The dark fpot on Mars is rather more advanced 
than it was May nth, at 10I1. 18k 
I oh. The fpot is vifibly advanced: I fuppofe it will take 
near an hour to come to the center. 
10 h. 15'. A very thick fog obfeures the fky. 
11 h. if. The fame darknefs. 
June 19. Clock 22" too flow by the tranfit of $ Scorph ob- 
ferved this evening, 
8 h. 40k The figure on the diik of Mars appears now to be 
as it was April 26, 1777, at 9 h. f, fee fig. 18. 
I I h. 30k 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 ' i 
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. 47k 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 1 1 th, at 
1 1 h. 43', but can certainly not be above two or three minutes 
from it. 
nh. 51k The undulation of the air prevents all further 
obfervation. 
Let us now examine the refult of the above mentioned obfer- 
vations : comparing together the two following fliort intervals 
of the year 1779, we have, 
Vol. LXXI. 
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