34 The Ottawa Naturalist. [May 



■^etc. This can readily be effected by putting field tiles around the 

 outside of the house wall 6 inches below the cellar level, and 

 having them connected with the glazed tiles which will then 

 carry away the ground water to the sewer. This is much more 

 important and successful than attempting to keep out the water 

 by laying cement floors and covering the walls on the outside 

 with cement and wood tar, although both these are of sup- 

 plementary value. ■ How much difference there is in soils may 

 be seen in the fact that different sands hold by capillary attrac- 

 tion from 15 to 25 parts in 100 of water, loam some 40 parts and 

 clay 75 parts. 



It is, however, most desirable that besides this drainage, we 

 have a non-conducting wall, since the moisture of a cellar is 

 often due to the wall of stone or cement being a good conductor 

 and so, by stealing away heat, condensing the moisture on the 

 cellar walls. This can be overcome by a wall with hollow 

 spaces, gotten either by using hollow blocks or making a two- 

 inch air space between the plaster and the wall, and providing 

 by windows or other method for circulation of air. 



Having arrived above the ground level, locality, as regards 

 the price of stone, cement, brick, wood, etc., will assist in deter- 

 mining of what materials the house win be built. As regards 

 warmth and dryness, it may be said, speaking generally, that 

 the thicker the walls the stronger and warmer the house ; but 

 to even & greater degree warmth depends upon the nature of 

 the materials used and the mode of construction. 



To illustrate, it may be said that a wall made of silver a foot 

 thick would be nearly ten times colder than one built of iron, 

 as its conductivity is 1,000 to 125, while one built of stone is 

 100 times colder than one foot of air hermetically sealed between 

 two boards, and glass 50 times colder, and brick 25 times colder 

 than confined air of the same thickness. 



It will be seen that this fact depends upon the relative 

 conductivity of different materials, and of all the best non- 

 conductor is a dr\' gas. We have to-day in a cement hollow wall 

 combined much more nearly than in any other material, the 

 elements of strength, warmth and cheapness, since while air 

 spaces can be had with wooden and brick walls, the former will 

 not remain close owing to its dr\'ing and warping, while a thor- 

 oughly good grouted brick wall with a really good air space will 

 be notabty more costly than cement. 



The aesthetic question must be decided in conjunction with 

 these several other elements. Having, however, gotten the kind 

 of walls settled upon we have something to determine regarding 

 the lighting of the house. The long side of the house ought, 



