76 LOCAL PAETrCULARS OF THE TRANSIT OF VENUS, 1874. 



We have thus i^apidly pointed out what is to be observed, and 

 the methods of doing it, and we come now to the consideration 

 of those points which are of local interest. And w^e notice that 

 Australia is not w^ell situated for observing the commencement of 

 the transit ; for since the question is one of parallax, those wdio 

 are best situated for observing it are those who are nearest to the 

 edge of the illuminated hemisphere of the earth, or whose posi- 

 tions, as seen from the sun, are as far from the centre as possible. 

 Now, as I have pointed out, one part of Australia as seen from 

 the sun will occupy the centre of the earth, and is therefore not 

 well suited for observation : but towards the end, circumstances 

 Avill have changed, and Australia will have moved so that the 

 south-east part of it will occupy a good position for observing 

 egress. In some respects I think it will be the best ; for although 

 we shall not be so well situated in regard to the actual amount 

 of disjDlacement or parallax as ]S^ew Zealand, we shall have nearly 

 as much, and a far better prospect of getting good observations, 

 both on account of the greater altitude of the sun and the 

 probable state of the w^eather, for I find that a great deal of rain 

 falls at the meteorological stations of New Zealand in December, 

 and the weather seems A^ery uncertain. 



For observing the end of the transit, then, according to Delisle's 

 method, which has been strongly recommended by tlie Astronomer 

 Koyal, we are w-ell situated for observing the accelerated egress ; 

 and for Halley's and the direct or photographic method, all parts 

 of Australia are available ; and it is my intention to make the 

 observations at each station serve for each of the three methods, 

 by observing the ingress and egress, and filling up the time by 

 taking as many photographs as possible. I communicated this 

 intention to the Astronomer Royal, and have received a letter 

 from hiui in which he says : — 



" No better arrangement for observing the transit of Venus can be made 

 than that which you propose, namely, to observe by eye at the telescope the 

 completed ingress and the beginning of egress (which I fully expect to be the 

 most accurate observation of all, noting carefully the two phenomena, of 

 when Tenus xeeins to be just wholly on, and when Yenus Ls- wholly on, as 

 shown by the breakmg of the ligament), and to fill vip the time by taking 

 photographs." 



The stations which are now provided for are Sydney, Eden, and 

 Blue Mountains — Sydney, because we have greater facility for 

 observation than is possible at a temporary station ; Eden, be- 

 cause it is near the best point of Australia, and within telegraphic 

 reach for determining its position ; and Blue Mountains as a 

 stand-by, in case the two coast districts are cloudy, and because 

 I find, from recent experiments, that the additional altitude adds 

 much to the probability of good observations. I have asked for 

 money for a fourth station, which, if granted, will provide for one 



