Each vertical interspace represents one degree Falirenlieit, and die fractional parts of a degree are indicated as exactly as possible in die plotting of die curves. Each fifth 

 degree is represented by a slighdy heavier line; The transverse interspaces inclosed by die heavier lines represent periods of ten days each, as indicated by tlie dates on the 

 left-hand side of the plate. The lighter transverse lines, intermediate between the heavier ones, are intended to represent the mean of each ten days, and the curves of temper- 

 ature ar,e plotted with reference to these lines. The left-hand verlicaL division is devoted to the air temperatures for i8Sr, 18S2 and. i8S3,the middle divisionto the surface 

 lyatfir teinperatures. for the same years- tlius permitting of a comparison of the two; and die right-hand division to the water temperat;ures for 1S84 andiSSs, 



