THE SUN'S MOTION IN SPACE. 219 



trative figure, that this statement is ill-founded. Neither the 

 direction nor the quantity of the solar motion has yet been ascer- 

 tained to a high order of precision, nor has the best method of 

 determination been established beyond dispute. The general 

 mean of the whole of the results, would indicate a point approx- 

 imately having the coordinates, and velocity, 



RA. = 270-5, D.= +23-9, V,=15-3, miles = 24 6 kilometres. 

 The question as to the value of this result, turns however upon 

 the decision as to whether the Besselian, or Argelanderian or 

 Airy method should be followed, and to some extent upon the 

 definition of what is meant by the solar motion in space. This it 

 is not proposed here to inquire into. It will suffice to say that, 

 per se, a mere mean has no strong claim to acceptance. In the 

 absence however of decisive evidence that a particular solution 

 should be adopted, such a mean can be taken as affording on the 

 whole a very probable value. 



In conclusion, I desire to express my appreciation of the very 

 kind way in which the astronomical literature of the Sydney 

 Observatory has been placed at my disposal by the Government 

 Astronomer, Mr. H. C. Russell, b.a., c.m.g., f.r.s., etc., and my 

 thanks to that gentleman for his kindness and courtesy ; also ta 

 Mr. J. Tebbutt, f.r.a.s., etc., proprietor of the Observatory at 

 Windsor, for similar kindness and courtesy. 



Figures 1 and 1 (a), and Tables I., II. and III., will be found 

 in the subsequent pages. 



