246 NINTH ANNUAL REPORT OF 



tell us the water came down not in drops but in streams, and that the 

 streets of the city were converted into flowing rivers and fathomless 

 quag-mires. The tubs and casks that were left out at night were 

 always found full and overflowing next morning. Unfortunately, there 

 was no rain-guage to verify these statemenis. Doubtless the rains 

 were copious at that time, probably much more so than since. But the 

 doleful traditions respecting them may be referred in part to the 

 absence of comfortable defences against the elements. The early settlers 

 had to reside in tents, or beneath cribriform roofs, and tread in 

 unplanked and submerged paths. These circumstances magnified and 

 multiplied the lalling drops, and penetrated the sufferers with indelible 

 hydropathic impressions. Hence the rainy winter of 1849-50 is 

 uniformly dwelt on with great pathos and eloquence by those who 

 endured it. 



The question may arise, whether the floods that occurred in March, 

 1852, did not require a larger supply of rain than fell at San Francisco. 

 But those who have not investigated the subject can form no adequate 

 idea of the immense quantity of water requisite to make an inch of rain. 

 Let us suppose the river Sacramento to drain a surface of one thousand 

 square miles, and the channel at Sacramento to be 200 yards wide. 

 Through this channel let one inch of rain be required to drain off" in 24 

 hours, with a current of four miles an hour. It is easiW calculated that 

 one inch of rain, falling on a surface of one thousand square miles, 

 would, under such circumstances, raise the river eight feet and keep it 

 at that height 24 hours. 



The presence of a few inches of snow, with the subjacent earth fro- 

 zen, so as to prevent it from imbibing, will greatl}^ enhance the diluvial 

 effects of even a moderate rain. The snow, first absorbs the water and 

 retains it until fully saturated, and then the entire mass rapidly liqui- 

 fies and flows off'. This was the case in the freshets that were precipi- 

 tated from the mountains and hills of California in March last. One of 

 the most destructive floods that ever occurred in eastern Pennsylvania 

 was occasioned by a warm rain of less than two inches, which fell when 

 the ground was frozen and covered with three or four inches of snow. 



It is one striking feature of the winter of California, that when the 

 weather puts on its rain}^ habit, the rain continues every day for an 

 indefinite period; and when it ceases, there is an entire absence of rain 

 for a long lime. Thus, after three days of rain in the first week of 

 December, 1851, the sk}^ was perfectly clear for 13 days. Then, be- 

 ginning with the 19th, rain fell every day for 13 days, or until the end 

 of the month. After this it continued clear for nearly two months, 

 there being but f^ur slight rains in January, and two in February, until 

 the 28th of the latter month, when the rainy diathesis again developed, 

 and rain fell daily for 12 days. After the 10th of March, there were 

 but four rains for more than a month. 



There appear to be two rainy seasons, rather than one — something- 

 like the early and later rains of Palestine. The one takes place in the 

 latter part of November or December, when the sea winds relinquish 

 their swa}^, and the other in March, when they are about to resume 

 their authority. Between those periods there is an interregnum of dry 

 weather. 



