^acli vertical interspace represjnts one degree Fahrenheit, and the h'actional parts of a degree are indicated as exactly as possible in the plotting of die curves. Each fiffll 

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

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

 ature are plotted widi reference to these Hnes. The left-hand vertical division is devoted to the air temperatures for 1881, 18S1' and 18S3, the middle division to the surface 

 ■fflatec temperatures for the same years, thus pennittiing of a comparisoa of the two; and the right-hand division to die water temperatures for 1SS4 and 1SS5. 



