THE COMING TRANSIT OF VENUS. 31 



exactly the same conclusion. The sole difference be- 

 tween his result and mine was, that he simply an- 

 nounced that Halley's method was advantageously 

 applicable, whereas I showed that it was more advan- 

 tageously applicable than Delisle's. Even this differ- 

 ance, however, is readily accounted for, since, in 

 Puiseux's investigation, several of the niceties to which 

 I had attended were neglected as unimportant. 1 



To show how completely the application of Halley's 

 method has been neglected in the choice of stations 

 for English observing parties, let the following con- 

 siderations be noticed : 



At northern stations Venus will be seen lower down 

 that at southern stations, so that as she transits the 

 upper part of the sun's disc, her chord of transit is 

 necessarily longer at northern than at southern stations. 

 Now Russia occupies the best northern stations, as is 

 her due, since they fall in Russian territory. At 

 Nertchinsk, near Lake Baikal, Russia will have an 

 observing party ; and here the transit will last longer 

 than as supposed to be seen from the earth's centre, by 

 fully 15^ minutes. For at this place the transit will 

 begin nearly 6 minutes early, and end nearly 10 

 minutes late. Now, if we had only a southern station 



and La Haye Sainte of the scientific Waterloo ; this country's duty calls 

 her to a post so important and so difficult of tenure, that it may fairly 

 be described as the Hougoumount of the position. 



1 For example, Puiseux left out of consideration the dimensions of 

 Venus's disc, regarding her transit as that of her centre. He omitted 

 also, as unimportant, the fact that mean time and apparent time are not 

 coincident on December 8. The correction due to this cause is consi- 

 derable. 



