140 On the Movement of Rocks, 
as it expands from the middle of the pond towards the shore, 
carries the rock along with it. The fact, that the ice does 
expand from the middle towards the borders, in all cases 
_ where water is frozen, must be evident to all oo 
with cold climates, and who have observe ed t 
stances in which ice is feeds When wateris “left to be 
frozen ina vessel, the expansion from the middle to the 
outside is so strong as to break the vessel. ‘This is some- 
times the case even where the vessel is ofiron. There is 
often, also, a considerable elevation in the middle of the 
ice resaltifig from. the ence of the sides of the vessel 
cpansi in ponds and lakes this 
vati ae on account of the im- 
mense weight of dhe 3 ar sand ‘ihe ‘little or no resistance to 
* The nana ab ice, though so great a force, that no known resist- 
ance can confine it, is always exerted in ei direction where there is least 
resistance. Is peg times repeated the following experiment before my 
classes, while Profenite 2 f Mathematics at the University in Rho de-Island. 
ing to the expansion upwards, a cine arrives at ength, when the peeve of 
etween r 
shore is inclined at a moderate angle to the abit ce of the water, anda 
esas - te Spas will take place. This - projection must hive often 
one accu , when thick ice is melt- 
ing a8 equent 4 = pe Hs beyond the edge ofthe water. And 
e of this ice be ined, the appearance dedicates that the 
lower part of the Peurerrt rhe een forced outwards. 
e shore is pereniiala to the water, or approaching to it, 
this aclossion ennnot na e in any considerable ve te — in such 
circumstances, I hav. dmg crac in many plac num 
rous bisiese joined at pany past elevated so as tobe gently inlined to each 
otherlike a very flat roof. This was the natural effect on the mechanical 
principles which must govern the results. My views on this part of the 
subject, are very much “confirmed ed by the circumstances of the ‘‘ Deerfield 
