i6o ENGINEERING ON THE FARM 



Metal sidings. Thin sheets of galvanized iron or tin may 

 be used as an outside covering for some buildings. They are 

 reasonably wind-tight, but transmit heat or cold and when 

 not kept painted deteriorate rapidly. 



Insulating materials. Insulating materials are used in 

 the construction of walls and floors to minimize the changes 

 due to outside temperatures. In houses and barns a higher 

 inside temperature is the object; in ice houses, the reverse. 



Paper. The lightest and cheapest kind of insulating 

 material is paper treated with various preparations. Rosin- 

 sized paper is short-lived. Tar paper is better, and asphalt- 

 saturated or coated paper still more satisfactory. Their 

 virtue lies in the length of time they will "stand up." One 

 which dries out and disintegrates in a short time is exceed- 

 ingly poor. 



Felt. Next in weight of the insulating materials are those 

 known as felts or quilts. These are made of hair, of sea 

 moss, of flax straw, or of various combinations, some with 

 a light short-lived stock of paper on one or both sides to 

 facilitate handling and placing. Another kind is a sheet 

 made of flax straw or tow which has been rolled into this 

 form after having been soaked for some time. It is very 

 stable, is not attractive to mice and rats, and possesses 

 the long life of the flax fiber. It is highly desirable for 

 insulating purposes and may be had in thicknesses up to 4 

 inches. This last is used in the insulation of ice houses 

 and dry kilns. Lith is one of the standard insulating 

 articles on the market. All fibrous insulations must be 

 kept dry; if allowed to become water-soaked, they are 

 difficult to dry and lose a large proportion of their insulat- 

 ing qualities. 



Cork. One of the best — though, at the same time, one 

 of the most expensive — insulating materials is cork, either 

 in the ground form or pressed into sheets or bricks. It has 

 a low absorption coefficient, and even when directly exposed 

 to water takes up a very small quantity. 



