Eacli vertical interspace represents one degree Fahrenheit, and the fractional parts of a degree are indicated as exactly as possible in the plotting o^ die curves. Each fifth 

 iJe»ree is represented .by a slightly heavier line. The transverse interspaces .inclosed by the heavier lines represent periods often days each, as indicated by the dates on the 

 Jeit-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 are plotted nritli reference to these lines.. The left-hand vertical division is devoted to the air temperatures for iSSi, 18S2 and 18S3, the middle division to the surface 

 ■water temperatures for the same years, thus permitting pf. a comparison of the two; and the right-hand division to die water temperatures for 1884 and 1885. 



