CLIMATE. 39 



constant decomposition of animal and vegetable manner, lying 

 on wet ground, under a hot sun, causes the air in other states 

 to be filled with such gases as are not set free to an equal 

 extent here. 



In May and June, all California " dries up" — the rivers, the 

 brooks, the springs, the ditches, the vegetation — and, with 

 them, many of the resources of the country. 



§ 29. Length of Days. — ^The shortest day in the year, the 

 20th of December, measures nine hours and four minutes be- 

 tween sunrise and sunset at Crescent City, and ten hours at 

 San Diego ; while the longest day, the 20th of June, measures 

 fifteen hours and seventeen minutes on the southern border, 

 and fourteen hours and nineteen minutes on the northei-n bor- 

 der of the state — or, measuring from the beginning of twilight 

 in the morning to the end of twilight -at night, the day meas- 

 ures nineteen hours and forty-seven minutes on the Siskiyon 

 Mountains, and seventeen hours and forty-three minutes at 

 Fort Yuma. 



§ 30. Thunder- Storms. — Thunder-storms are very rare iu 

 California. Lightning is not seen more than three or four 

 times a year at San Francisco, and then it is never near, but 

 far off, playing about the peak of Mount Diablo. Thunder is 

 still more rare. Indeed, many persons have been here for 

 years, and cannot say that they have ever seen the one or 

 heard the other. During eleven years' residence in the state, 

 I have never seen a brilliant flash of lightning or heard a loud 

 clap of thunder. Thunder-storms are sometimes witnessed 

 high up in the mountains, and in the Great Basin ; very rarely 

 in any of the low land of the state. In May, 1860, a house in 

 Sonora was struck by lightning; and in February, 1861, three 

 vessels in Humboldt Bay were struck in the same manner: 

 and, though there were persons in the house and on all the 

 vessels, no serious injury was done to either person or prop- 

 erty in any case. On the 25th of May, 1860, a Chinaman was 



