ASTRONOMY ON THE PACIFIC COAST 



215 



21. Important studies of the spectra of spiral nebulfe and star clusters have 

 been inaugurated. 



22. An atlas of the moon was made in the first year of the observatory's 

 existence, on the basis of photographs obtained with the large telescope. 



23. The motions of approach and recession of about 1,500 naked-eye stars, 

 distributed over the entire sky, have been observed with the 36-inch refractor at 

 Mount Hamilton and the D. O. Mills reflector at Santiago. 



The 36-inch Refeactor of the Lick Obsekvatoet. 



24. Spectroscopic observations at Mount Hamilton and on the summit of 

 Mount Whitney have shown that the atmosphere of Mars is of low density, prob- 

 ably much less dense at the surface of Mars than the earth's atmosphere is at 

 the summit of the highest peak in the Himalaya Mountains. These observa- 

 tions have established likewise that the quantity of water vapor in the atmos- 

 phere of Ma7-s above, say, a square mile of its surface, must be very slight as 

 compared with the quantity of water vapor in the earth's atmosphere above an 

 equal area. 



