Each ventjcal intecspaee represents one degree Fahrenheit, and the fractional parts of ^a degree are indicated as e.xactly as possible in the plotting of :the curves. Each fifth 

 ic^ree is represented by a slightly heavier line, The transverseainterspaces inclosed by tlie heavier lines represent periods of ten days each, as indicated by the dates on the 

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

 Bturci are plotted'withjjeference' to these lines. The left-hand vertical division is devoted to tlie air te.-nporatures for I'JSi, 10S2 and 1S83, the middle division to die surface 

 ■water temperatures ibrtlie sam&years. thus pennitting of a comparason-of the two; aad the tightJiand division to the watertemperatnres for i884Liand 1883. 



