232 



SOLAR MOTION. 



sent limits do not permit me to say more, it must be ob- 

 served, 1. that in cinnabar, whether natural or artificial, 

 .the metallic base, like all the other metals, at their lowest 

 degree of oxidation, resists solution in the nitric acid ; 

 ^. that in the fabrication of cinnabar in the dry way, is 

 always accompanied with an inflammation which appears 

 tome to be an oxidatimi. 



XL 



On the Quantity and Velocity of the Solar Motion. By 

 William Herschel, L.L, D. F. R. S. From the 



Philosophical Transactions for 1806. 



nr . . 



Investigation -^ HE direction of the solar motion having been suffi- 

 of the proper ciently ascertained in the first part of this paper*, we shall 

 ^ * ^ ^ now resume the subject, and proceed to an inquiry about 

 its velocity. 



The proper motions, when reduced to one direction, 

 have been called quantities, to distinguish them from the 

 volocities required in the moving stars to produce thoso 

 motions. It will be necessary to keep up the same dis- 

 ' - tinction with respect to the velocity of the solar motion ; 



for till we are better acquainted with the parallax of the 

 carth^s orbit, we can only come to a knowledge of the 

 extent of the arch which this motion would be seen to 

 describe in a given time, when seen from a star of the first 

 magnitude placed at right angles to the motion. There 

 is, however, a considerable difference between the ve« 

 locity of the solar motion and that of a star ; for at a 

 given distance, when the quantity of the solar motion is 

 known, its velocity will also be known, and every approx- 

 imation towards a knowledge of the distance of a star of 

 the first magnitude will be an approximation towards the 

 knowledge of the real solar velocity ; but with a star it 

 I will be otherwise ; for though the situation of the plane 



in which it moves is given, the angle of the direction 



♦ Phil. Trans, for 1805, page 231 ; or see our Journal, Vol. XIII. 



Of 



