166 TRANSIT OF MERCURY. 
the time of external contact as observed by me with 7}ineh 
_ refractor and power 150, Sh. 21m. 44°64s, The circumstances were 
time taken was when I was certain internal contact was made; as 
the definition continued very bad it may be late. The sun being 
tower I used the 114-inch refractor with 6inch 
stop, and a polarizing eye-piece without coloured glass, magn 
fying powers from 100 to 200 were used, some having 
lenses; but though the planet was very carefully watched for halo, 
seen. During the forenoon from about 9 a.m. thin cuTus clouds 
were forming and steadily shutting out the sunlight but the 
optical illusion, caused by the vibration, which transposed rapidly 
on my retina the dark planet and bright sun. I did not see 
‘was repeated several times in as many seconds, and then ceased, 
bs, and 
