^cli .vertical interspace represents one degree Fahrenheit, and tlie fractional parts of a degree are indicated as exactly as possible in tlie plotting of flie curves. Each fifth 

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

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

 Bture; are: plotted with reference to these lines. The" left-hand vertical division is devoted to the ait temperatures for 1881, J882 and 1883, the middle division to the surface 

 water temperatures for the same years, thus permitting. of a comparison of the two; and the right-hand division to the water temperatures for 1884 and 1S85. 



