SURGEONS REPORTS — CALIFORNIA — NORTHERN DISTRICT. 



485 



Tabic of successive hourly ranges of the thermometer for 1857. 



The mean daily range for each month is exhibited in the subjoined table, which embodies the 

 two last years' observation with the thermometrograph : 



Dividing the year into its meteorological seasons, the mean daily range will be as follows : 

 Spring, (February, March, i;nd April,) 15° 84' ; autumn, (October and Js^ovember,) 16° 83' ; summer, 

 (May, June, July, August, and September,) 19° 64' ; winter, (December and January,) 12° 18'. 



Iteverting to the table of montlily and annual means, we find the resi)ective mean tempera! nre of 

 the seasons to be as follows: For the spring months, mean, 55° 31'; the mean maximum being 

 71° 20', and the mean minimum, 42° 13'; for the summer, mean, 70° 19', and the mean maximum 

 and minimum, 92° 50' and 55° n' respectively; for the autumn, meau, 58° 47' ; and mean maximum 

 and minimum, 78° 20' and 44° 00' respectively ; in the two winter montlis, is 45° 94' ; the mean 

 maximum, 00° 90', and the mean minimum, 29° 70'. Thus it is demonstrated that there is a mean 

 difference between winter and spring of 90 35' ; between spring and summer of 14° 88' ; between 

 summer and autumn of 11° 72'; and between autumn and winter oi' 12'' 52'. The dilference of 

 means of the hottest and coldest months, between summer and winter, is also shown tfl be 24^ 25' ; 

 and the extreme variation, or the difference between the meiin maximum of the former and mean 



