118 NEW MEASUREMENTS OF DISTANCE OF SUN. 



But it is interesting to speculate whether astronomers will ever be 

 in the position to say, '' We have now determined the solar parallax 

 in seconds of arc to a higher degree of accuracy than that of the 

 measurement of the earth,"' and to call upon geodesists for better re- 

 sults. I can conceive only one direction in which we may be able to 

 worry the successors in your corps of Everest and Clarke. Is the 

 form of the eipiator a circle or an ellipse? I believe that there is 

 some j^light evidence for ellipticity, and that it has been put as high 

 as one in three thousand. If that is so, it is just barely possible that 

 we may have to introduce into the computation of the parallax factors 

 for different observatories a term depending upon the shape of the 

 (equator. But I confess that this prospect is remote, and that for 

 many years, in all probability, geodesists who achieve accuracies of 

 ^ne in a hundred thousand and even talk of one in a million will be 

 able to take a serene view of the labors of astronomers to arrive at 

 the distance of the sun to one part in ten thousand. 



