292 TRANSACTIONS OF THE 



makes a very agreeable table water. An analysis by Professor Hilgard, 

 shows — 



Grains 

 per Gallon. 



Carbonate of soda 0.27 



Chloride of sodium, sulphate of sodium 1.42 



Carbonate of lime..- 0.31 



Carbonate of magnesia 0.25 



Silica -- 1.85 



Sulphate of lime. 0.42 



Phosphate of lime - - - 1.48 



Iron and maganese carbonates. - - 0.63 



Alumina- -.- -.- 0.07 



Vegetable matter -- 0.00 



Total .- - 1 6.69 



This equals the average drinking water in any locality. 



The climatology of Sacramento bears a general resemblance to that of 

 the great valley in which it lies ; the mean annual temperature for the nine 

 years ending 1886 being 60.2°, the mean, maximum, and minimum, being 

 82.5° and 41.4°, giving a range of 41.1°; extremes of temperature are absent, 

 the winters being mild and the summers uniformly cool. This is perhaps 

 best shown by the fact that in the nine years from 1878 to 1886 there have 

 been only 96 days on which the temperature was below 32°, and but 331 

 days on which the mercury rose above 90°, giving an annual average of 10 

 and 37 days respectively. The great feature which renders the summer 

 climate pleasurable is the universal prevalence of cool nights; the mean 

 temperature of the nights from June to August, during the years 1877 to 

 1887, was 60°, and there were only nineteen nights in which the thermom- 

 eter stood at or over 70°. This fact is due to the trade wind which reaches 

 us as a south breeze at about 4 p. m., and continues blowing with a mean 

 summer velocity of seven miles till early morning. The numerous shade 

 trees and liberal sprinkling of the streets in summer perceptibly lower the 

 temperature during the days of extreme heat. 



The seasons are divided distinctly into dry and wet. The latter com- 

 prises the months of November to May, the dry from June to October. The 

 months of greatest precipitation are December and January. For the 

 thirty-seven years from 1850 to 1886, the maximum precipitation was 34.92, 

 the minimum 8.44, giving a mean of 19.60. The mean relative humidity 

 for the years 1879 to 1884 was 67.4, or 60.2 for the dry and 72.8 for the wet 

 seasons. 



The prevailing diseases are those of a malarial type. This is invariably 

 of a mild form, the malignant ague of the Southern and Middle States 

 being here of the rarest occurrence. Malaria is now much less prevalent 

 than in former years, and shows a steady annual decline in the number of 

 cases, as well as in the change from remittent and quotidian to the milder 

 second and third day fevers. This change is due to improved drainage, the 

 general elevation of the city level, and to the great increase in the amount 

 of ground under cultivation. With the exception of malarial trouble there 

 is no endemic disease in the Sacramento Valley, and this prevalence is now 

 due to the fact that throughout the county the greater portion of the rural 

 population is located on the rich bottom lands of the Sacramento, Amer- 

 ican, and Cosumnes Rivers. Each season brings its quota of disease to 

 which atmospheric conditions may predispose, but speaking generally it 

 may be stated that owing to the milder climate, the diseases of exposure 

 are here less prevalent. In considering the subject of vital statistics, it must 

 be borne in mind that in common with other centers of population, Sacra- 

 mento receives annually many invalids whose deaths ought not properly to 



