-1859] WRITINGS OF JOSEPH HENRY. 205 



ing up however be too great, cracks are produced at the most 

 elevated parts. 



After a quantity of water has been solidified it ceases to 

 expand ; and with a still further diminution of temperature 

 shrinks, in accordance with the law to which all solid bodies 

 are subjected. Indeed it is now known that most liquid sub- 

 stances which pass into the solid state enlarge their volume 

 at the moment of transition, and that the phenomenon ex- 

 hibited by ice is only a conspicuous illustration of a general 

 rule. Ice once formed is found to shrink more rapidly with 

 a diminution of temperature than any other substance on 

 which experiments have yet been made. 



The expansion of water and shrinking of ice serve to ex- 

 plain a variety of phenomena presented in the operations of 

 nature and the processes of the arts. Those who reside near 

 the borders of rivers or fresh-water lakes are often startled 

 during cold winter nights by explosions apparently as loud 

 as those of discharges of heavy ordnance. These are pro- 

 duced by the rupture of long lines of ice — the gradual shrink- 

 ing of which has been going on during the reduction of tem- 

 perature tending to bring the whole mass into a state of ten- 

 sion, which is relieved by the sudden giving way along the 

 line of least strength. I am informed by Captain M. C. Meigs, 

 who has paid particular attention to the cracking of ice on 

 Lake Champlain, that it most frequently takes place in the 

 narrower parts of the lake — the shrinking of portions on 

 each side of this line of least resistance tends to separate the 

 two masses. The water sometimes rises in the cracks thus 

 formed, a new freezing takes place, and when the weather 

 moderates and the field expands to its original dimensions, 

 it becomes too large for the area it covers, and long ridges 

 are thrown up. 



A similar effect is sometimes produced on the surface of 

 damp ground subsequently frozen. During the winter of 

 1856 and 1857, we received accounts of injury done to several 

 brick houses by the separation due to the shrinking of the 

 surface, passing through the foundation of the edifice, and 

 extending up along the walls. We might infer from the 



