200 Economical Mode of building 



The form, then, of these beams is somewhat as in^^. 59. ; 

 59 



in which a is the side view, h the cross section, and c the plan 

 of the bottom rib. 



I have particularly mentioned these beams, from their 

 novelty of form, and their importance, as saving nearly one 

 fourth part of iron ; in other words, 75 tons of iron will bear 

 as much in this form as 100 tons in the common ones. 



Such beams, then, suited to the weight to be borne, and 

 the length of the beam, &c., would support ^-inch brick 

 arches ; the haunches of which should not be filled up, but 

 spandril walls built across, at certain intervals, level with the 

 crowns of the arches, and there built open. Thus ventilation 

 would be permitted between the rick and its support ; and, 

 when the roof was uncovered, would conduct the rain off. 



Such arches should be turned in summer, and two or three 

 coats of coal tar given to the extrados surface, by which they 

 will be made watertight. I have constructed many such roofs 

 as these, for various purposes, and they have been found to be 

 light, cheap, strong, and staunch. 



All buildings thus constructed would obviously be fire- 

 proof, and would last an indefinite length of time. The 

 appearance of a tool-house so constructed will be as 'mjig. 60. 



Sheds of this kind may be used for storing any garden or 

 field produce, however damp : no matter what is stacked 

 above, as no evaporation will permeate the roof. 



The shorter the bearings of the beams of the roof (I call 

 them beams, although, in most instances, they would be very 

 slender), the greater will obviously be the saving of metal : for 

 most purposes, 7 ft. or 8 ft. from post to post will be sufficient. 



The appearance of such buildings might be much improved 

 by a kind of cornice of two projecting courses of bricks 

 round the tops of the walls. Corrugated iron might also be 

 used for such flat roofs, arranged in ridges or arches from 

 beam to beam ; and the upper ribs of the beams might be 

 hollowed to carry off the rain. 



So much for these roofs and walls. All J have written 



