458 NATURE'S TEACHINGS. 



cracked by the freezing of the water. The most common, and 

 perhaps the most unpleasant, example of this propensity is the 

 bursting of water-pipes in the winter, followed by a flooding of 

 the house when the thaw comes. 



This is caused by the expansion of the frozen water, which 

 will burst not only a thin leaden tube, but a stout iron vessel. 

 Care should therefore be taken, at the beginning of winter, to 

 cover up all exposed portions of leaden pipes, and there will 

 then be no danger. There was one pipe in my house that was 

 always bursting, but after I covered it with two or three layers 

 of carpet placed loosely over each other, so as to entangle the 

 air and form a non-conductor, the pipe has never frozen, and 

 the water supply has been uninterrupted by the severest 

 frosts. 



I am told that a still better plan exists, especially in places 

 where the pipes cannot be thoroughly protected by external 

 wrappings. Let six inches or so of the leaden pipe be removed, 

 and its place supplied by a vulcanised india-rubber tube. 



The ice must expand somewhere, and chooses the spot where 

 least resistance is offered to it. Consequently, it expands in 

 the india-rubber tube, but does not break it, and, when the 

 thaw comes, there is no overflow of water. 



MAN utilises this power of ice in stone-splitting. Instead of 

 taking the trouble to cut the stone by manual labour, the work- 

 men bore a series of holes, fill them with water, insert tightly 

 a wooden plug to prevent the ice, when formed, from oozing 

 out of the holes, and leave the rest for the frost to do. 



A like effect is produced in the warm weather by sub- 

 stituting similar plugs, but quite dry, having been baked for 

 hours in an oven, for the purpose of driving out every particle 

 of moisture. These plugs are hammered into the holes as 

 deeply as they will go, and there left. Even if there be no 

 rain, the nightly dews make their way into the pores of the 

 dry wood, and cause it to swell with such irresistible force 

 that the stone is split with scarcely any manual labour on the 

 part of the workmen. 



YET another plan for cutting hard stones. Some of my 

 readers may be aware that a singularly ingenious instrument 



