56 Dr. B. F. Harrison on Solution of Ice on Inland Waters. 
as in the last, although the temperature of the atmosphere 
was much lower,—so low, indeed, as to cause a constant loss of 
heat from the waters of the lake even by bad conductors. The 
water was at no point found as high as 42°, not even at the bot- 
tom, although it was as high as last year.” 
The observations made during the summer and autumn of 1860 
show that the water at the bottom of the lake (at a depth of 25 
feet,) attains a temperature above the mean of any month in the 
year in this latitude. How much of this heat is imparted to 
the earth, or to what depth it feanieaies, I have had no means 
of observing. The rapidity with which the enter receives heat, 
after the surface is covered with ice, is as conspicuous this 
season as it was the last. iin Dee. 17th, sie 7 ng oa 1861, 
(19 days), the temperature of the lake rose m Jan, 
5th to the 23d, (18 days), the paces of as ake aa only 
0°-7, with a difference of on! o degrees in the mean tempera- 
_ ‘of the atmosphere. From 6 an. 23d to Feb. 1, (8 days), there 
no perceptible change, but from Feb. 1st to the 27th the 
lamipesiitie of the water rose 2°°8; the temperature of the at- 
mosphere had in the mean time risen too high to allow any loss 
“a heat in that direction, and even sufficiently high to supply 
eat. 
On the approach of spring, when the a and the i —— 
heat of the atmosphere have thinned the ice and opened s 
holes so that the winds may agitate the sina this peat sor 
of heat accumulated in the lower strata of waters, which n 
have their unstable equilibrium disturbed, begins to be apple 
to the ice, which under such circumstances could not be expected 
to resist solution more than a few hours. 
It should be remembered that the mean temperature of the 
earth at a depth of twenty feet is sufficient to supply a ines 
amount of heat to the bottom of the lake in winter, indepen 
ent of any accumulation during the warm seaso 
Similar observations were continued in the winter of 186162, 
with results so exactly pr seer with the preceding, that their 
presentation could be of no r value than to confirm the 
conclusions which bese! Se bet given. 
* The thermometer used in the winter of 1860 and ’61 gives temperatures & 
fraction of a degree lower than the thermometer used the previous year. The ob- 
ions for the summer and autumn of 1860 and winter of 1861 were made with 
a self-registering thermometer constructed by James Green of New York. 
