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winter from the year eighteen hundred and forty-nine on. The horizontal lines represent 

 inches of rain, and the distance from the base or zero line at which each curve crosses the ver- 

 tical line appropriate to any year, indicates the amount of rain which fell in San Francisco 

 during that year. The three diagrams represent respectively the rainfall before the first of 

 January, after the first of January, and the total rainfall. The scale of years is continuous, 

 and is the same for all the curves; the scale representing inches, on the other hand, is different 

 for each, and is inversely proportional to the amount of rain which has fallen during the period 

 covered by the diagram. The consequence of this selection of scales will evidently be that if 

 the amount of rain falling before the first of January were simply proportional to the total 

 rainfall for the season, and if, in each year, just two-fifths of the rain came before January 

 first, the three curves would be identical. Hence, their variation expresses exactly the limits 

 within which this rule applies. 



As your readers are interested in the weather, perhaps some of them may find this chart a 

 convenient record of the past. 



G. F. BECKER. 



University of California, December 20th, 1877. 



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