VENUS ON THE SUN'S FACE. 85 



that the transit-observations will fail through meteoro- 

 logical causes is very largely diminished. Science will 

 owe much to the generosity of England in this respect. 



It is, indeed, only recently that the possibility of 

 applying Halley's method has been recognized. It 

 had been thought that the method must fail totally in 

 1S74. But on a more careful examination of the cir- 

 cumstances of the transit, a French astronomer, M. 

 Puiseux, was enabled to announce that this is not the 

 case. Almost simultaneously the present writer pub- 

 lished calculations pointing to a similar result ; but 

 having carried the processes a few steps further than 

 M. Puiseux, he was able to show that Halley's method 

 is not only available in 1874, but is the more powerful 

 method of the two. 



Unfortunately, there is an element of doubt in the 

 inquiry, of which no amount of care on the part of our 

 observers and mathematicians will enable them to get 

 rid. "We refer to the behavior of Yenus herself. It 

 is to the peculiarity we are now to consider that the 

 2^<m'-failure of the observations made in 1769 must 

 be attributed. It is true that Mr. Stone, the eminent 

 first-assistant at the Greenwich Observatory, has man- 

 aged to remove the greater part of the doubts which 

 clouded the results of those observations. But not 

 even his skill and patience can serve to remove the 

 blot which a century of doubt has seemed to throw 

 upon the most exact of the sciences. We shall now 



