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

 degree is represented by a slightly heavier Vm& The transverse interspaces inclosed by the heavier lines represent periods of ten days each, as indicated by die dates on the 

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

 afure are plotted vnth reference to these lines. The left-hand vertical division is devoted to the air temperatures for i88i, 18S2. and 1883, the middle division tQ the. surface 

 ■water temperatures for the same yeacsj thus permitti ng of a comparison of die two ; and the right-hand division to the water temperatures for 1 SS'^t and iSSs- 



