36 EESOUUCES OF CALIFOENIA. 



There was, then, a f^ill of three feet of water over an area of 

 about twenty-two thousand five hundred square miles, and a 

 fall of eight and a half feet over an area of fifteen thousand 

 square miles. This would give us an average of five and one- 

 fourth feet over an area of thirty-seven thousand five hundred 

 square miles. The first foot was absorbed by the sand and 

 earth, dried during a very arid summer and fall; and then 

 there were four feet of water to escape through an outlet half 

 a mile wide, from an area nearly as large as England, or the 

 state of Ohio. 



The outlet proved insufficient: the waters heaped them- 

 selves up in the lowest part of the Sacramento Basin, the size 

 of wliich low portion I have already given as one hundred and 

 fifty miles long and twenty wide, or an area of three thousand 

 square miles. Now, four feet of water over an area of thirty- 

 seven thousand five hundred square miles, Avill, if collected 

 within three thousand square miles, form a body forty-eight 

 feet deep ; and that figure represents the amount of water that 

 had to escape through the Sacramento River, below the mouth 

 of the San Joaquin. It is to be observed that, as the outlet of 

 the Sacramento Basin is in its centre, so the freshets come 

 simultaneously from the north and from the south. The rains 

 fall along the whole length of the Sierra Nevada at the same 

 time ; and as the mountain-streams are short and swift, they 

 pour down their floods immediately and all together. Such 

 are the circumstances which contributed to the great flood of 

 1862, and may contribute to other floods in the future. 



During January, 1862, 24.36 inches of rain fell in San Fran- 

 cisco, according to records kept by Thomas Tennant, Esq. ; 

 8.66 inches fell in Sacramento, according to Dr. T. M. Logan ; 

 37.79 inches fell at Downieville, according to Dr. T. R. Kibbe ; 

 and 33.79 inches fell in Grass Valley, according to Mr. Atwood. 

 I presume that all these figures are correct save those for San 

 Francisco ; and while I admit the care and accuracy of Mr. 

 Tennant, I must suspect that somebody played tricks with his 

 gauge, upon which he could not keep a constant watch. 



