46 



THE TEANSIT OF MEECUEY, MAY 10, 1891. 



Observations taken at Private Observatory, 

 Launceston. 



By A. B. Biggs. 



The morning of the 10th set in with a dense fog, hiding 

 the sun from view. However, a few minutes before the 

 expected entrance of the planet upon the sun's face (which 

 was set down as 9h. 42min. 15sec. local mean time), the fog 

 partially broke, giving promise of a clear view of the transit, 

 a promise which was by no means fulfilled. A haze again 

 covered the sun just before the critical moment, but a careful 

 watch was kept on that part of the sun's limb where the 

 planet was to enter. At 9h. 43min. 56sec. a partial clearing 

 allowed a decided notch to be seen on the sun's edge. Of 

 course the actual contact must have taken place somewhat 

 earlier. The internal contact, so far as could be judged, 

 occurred at 9h. 45min. 58sec. At 9h. 51min. 17sec. the 

 planet was estimated to be one diameter within the sun's 

 limb. During this time a local cloud condensation was 

 taking place which almost prevented further observation, 

 allowing, however, an occasional glimpse between the clouds, 

 but through a haze at best. The alternate partial brighten- 

 ing and overshadowing was exceedingly baffling, and as a 

 consequence the programme which I had laid out was seriously 

 interfered with, besides necessitating a frequent changing of 

 the apparatus to suit the varying conditions. About noon I 

 found the speculum so bedewed that I could not see my face 

 in it, and I had to take it out and warm it at a neighbour's 

 fire. I feared at first that the silver film was destroyed, as 

 the moisture appeared to have got underneath it. However, 

 after a careful warming it came all right, and I had no further 

 trouble with it. 



There was a clear, well-defined spot on the sun's southern 

 hemisphere, not large, about half a minute in diameter as 

 nearly as I could estimate, including penumbra. Between 

 this and the planet I managed to get a few chance micrometer 

 measures, during the intervals of comparative brightness. 

 Whilst engaged in this a bright spot on the centre of the 

 planet's disc caught my attention, apparently as if the sun 

 were shining through a hole in the planet. A similar ap- 

 pearance has been noted by some observers of previous 

 transits, but the thing seems so unaccountable and improb- 

 able that it has been attributed to optical illusion. However, 

 I could have no doubt of its reality on this occasion. The 

 following note is from Chambers's Astromony : — " The 



