66 STRUCTURES ADAPTED TO PARTICULAR PURPOSES. 



The ridge-and-furrow roof may be formed by placing the 

 rafters as in making a common roof, say four feet apart; then 

 placing the ridge-bars in such a manner that, contiguous to each 

 other, they will form an angle of 45 with the furrow-bar, or 

 rafter. Or the angle included within the ridge-bar may be 

 formed to suit the climate of the neighborhood, bearing in 

 mind the principles already laid down regarding the effects of 

 intense sunshine upon flat roofs. 



The sides of the ridge may be glazed of small panes, as in 

 common sashes, or may be made of single panes, as in the finest 

 houses now erected ; but, whichever method is adopted, the 

 rafters should terminate in one horizontal line on the top of the 

 parapet : this is also desirable at the back wall. Some apparent 

 difficulty is thus occasioned in the lower part of the roof; but 

 this difficulty is only apparent, especially if the front of the 

 ridge be made to slope on the same angle as the side. Only 

 the smaller and triangular pieces of glass can be used. It 

 becomes, in fact, more economical, as the smaller pieces of glass 

 may be all used up, which would, otherwise, be thrown away. 



The ridge-and-furrow roofs are especially advantageous in 

 countries liable to heavy falls of snow or rain, and in large 

 houses which are parallelograms in plan. Almost any w r eight 

 of snow may be carried by such roofs, especially where the fur- 

 row is small, as the pressure will then be chiefly on the bars 

 and rafters, and not on the glass. As to hail, which is some- 

 times very heavy in this country, breaking the glass in flat-roofed 

 houses, it will always meet the glass of a ridge-and-furrow house 

 at an angle which will prevent breakage. 



The advantages of these ridge-and-furrow roofs, as we have 

 already stated, their presenting the surface of the glass at an 

 oblique angle to the noon-day sun, while the morning and even- 

 ing sun is admitted almost perpendicular to the surface on 

 which it falls, ought not to be altogether overlooked in this 

 country; and we think that a great deal might be done with 

 houses of this kind, probably upon an improved plan, where- 

 by the effect of the intense sunshine of mid-summer might be, in 

 some measure, deprived of its meridian force upon glass-houses. 

 Whatever may be thought of the plan here given, the principle 



