(338) 



represents the moist year. The differences in evaporation 

 between different forest types on Mt. Desert Island less than 

 4 miles apart, were very much greater than the differences in 

 evaporation in the hemlock type, even including Cranberry 

 Lake. For example, taking white pine and spruce, both with 

 complete forest canopies casting practically full shade similar to 

 hemlock; white pine was 1 1.6 as against 4.0 for spruce in the wet 

 year, and 17.4 as against 7.0 for spruce in the dry year. Compare 

 these figures with a range of only from 12.2 to 7.5 for hemlock at 

 The New York Botanical Garden and the Adirondack Mountains. 

 Furthermore, it is of more than passing interest that the hemlock 

 evaporation, taking the stations as a whole, fits remarkably well 

 into the Mt. Desert island series, being distinctly higher than 

 spruce and lower than white pine, just as we would expect. 



The similarity between the different hemlock stations shows 

 not only in the seasonal averages, but on the chart of weekly 

 evaporation. Cranberry Lake stands out on account of being 

 the lowest, but the others criss-cross inextricably. We can 

 perhaps get some of the relationships by counting the number 

 of times (weekly readings) each station was the highest of all. 



The chart covers 22 weeks, from May 12 to October 5 inclusive. 

 Cranberry Lake does not begin till May 19 and ends September 

 21, but this does not affect the following figures. The New 

 Haven ridge top was highest 6 out of the 22 weeks, Ithaca was 

 highest 5 times, New York 4 times, and Cranberry Lake twice. 

 During the other 4 weeks the Ithaca hardwoods were highest. 

 The north slope at New Haven was never highest. This gives 

 an indication of how the curves cross and re-cross. The averages 

 given in Table I represent conditions fairly well. 



Precipitation 



The total precipitation at each station from May 12 to Septem- 

 ber 21 is given in Table I. The charts of precipitation need not 

 be reproduced. The curves for the stations outside of New York, 

 and New York hemlock, across and recross owing to the different 

 time at which the precipitation occurs. The New York curves 

 run along close together. 



We were fortunate in being able to secure figures for the pre- 

 cipitation in the open near the other stations as well as at New 

 York. For the New Haven stations the Water Company has a 



