MOUNTAIN OBSERVATORIES IN AMERICA AND EUROPE. 



55 



The rainfall for the month of December, 1884, was 83.8 inches ! The 

 following summary of rainfall and temperature observations will be 

 found interesting and instructive : 



SUMMARY OF RAINFALL AND TEMPERATURE OBSERVATIONS FROM 

 SEPTEMBER, 1880, TO NOVEMBER, 1893, INCLUSIVE, AT THE LICK 

 OBSERVATORY [COMPILED BY C. D. PERRINE]. * 



Month. 



July 



August . . . 

 September 

 October. . . 

 November 

 December . 

 January. . 

 Februarj' . 



March 



April 



May 



June 



Annual . 



inches 

 0.00 

 0.01 

 0.30 

 1.44 

 2.56 

 9.06 

 3.85 

 4.31 

 5.63 

 3.68 

 1.76 

 0.59 



33.18 



TEMPERATURE (Fahr.). 



S M 

 > 03 



79.3 

 80.0 

 73.5 

 62.9 

 56.3 

 49.7 

 48.4 

 47.9 

 51.0 

 58.5 

 64.0 

 70.0 



61.8 



-us 



60.6 

 63.3 

 56.1 

 46.9 

 41.5 

 36.3 

 36.6 

 33.6 

 37.0 

 37.1 

 46.9 

 51.1 



45.6 



69.9 

 71.7 

 64.8 

 54.9 

 48.9 

 43.0 

 43.5 

 40.7 

 44.0 

 47.8 

 55.5 

 60.5 



53.7 





94 

 96 

 93 



73 

 74 

 80 

 83 

 90 

 93 



°'B a 



36 

 39 

 30 

 25 

 26 

 17 

 14 

 13 

 18 

 31 

 38 

 31 



> cS cS 



18.6 

 16.7 

 17.4 

 16.0 

 14.7 

 13.4 

 11.8 

 14.3 

 14.0 

 21.4 

 17.1 

 18.9 



16.2 



The following short table exhibits the facts as to the humidity of 

 the air at Mount Hamilton. During the favorable months for observ- 

 ing, the air is usually extremely dry : 



RELATIVE HUMIDITY AT 9 P.M. (100 = COMPLETE SATURATION). 



The best possible tests of the condition of the atmosphere are to be 

 had from actual astronomical observations. It may be of interest to 

 recall a few made at Mount Hamilton during the years 1888-1896 

 which exhibit either the transparency or the steadiness of the atmos- 

 phere. 



Separation and measurement of dose double-stars : The long series of 

 * Publications of the Astronomical Society of the Pacific, vol. vi, p. 47, 



