STELLAR SYSTEMS AND NEBULAE. 213 



measured the radial velocities of ten nebulae. 

 He found that the well-known planetary nebula 

 in Draco was moving towards the Solar System 

 at the rate of 40 miles a second; for the 

 Orion nebula he found a motion of recession of 

 11 miles a second; but probably this belongs 

 chiefly to the movement of the Solar System in 

 the opposite direction. 



Unfortunately Keeler did not live to carry 

 on his investigations in nebular astronomy. His 

 early death brought to an abrupt end these 

 fruitful investigations. Appointed director of 

 the Lick Observatory in 1898, he died suddenly 

 at San Francisco on August 12, 1900, at the 

 early age of forty-two. 



