CONSTRUCTION. 



29 



a floor of this description. In this case the joists are 9 inches 

 by 3 inches, and 26 feet 6 inches long ; they are supported in 

 the centre by a longitudinal girder, 10 inches by 4 J inches, 

 40 feet long, and resting at either end on the stone template of 

 a brick pier and built into the wall, with three cast-iron columns 

 as its intermediate supports. The joists have two rows of 

 herring-bone strutting, one on either side of the girder, and are 

 15 inches from centre to centre. The columns, which are 

 shown in detail by Fig. 5, Plate 54, are 9 feet 9 inches in height, 

 and weigh 3J cwt. each. They are socketed into a block of 

 Portland stone, resting on concrete. The boards are i J inches 

 thick, planed on the upper surface, and grooved and tongued 

 with hoop iron. 



Posts of wood are also used as supports, in many cases fitted Posts for 

 into cast-iron sockets, as shown in Fig. 7 on the same Plate, ^*^^^^' 

 bedded on stone or concrete, and tenoned into the under side 

 of the girder. The floors of corn-stores should be made to 

 carry a weight of 2 J cwt. per foot super. 



The floor of the corn-store and hayloft 

 over the car-shed at Cambridge was 

 boarded, and Fig. 11 shows a section of 

 the oak sill and rolled girders carrying 

 the floor over the gateway to the car- 

 shed at H, on Plate 51. 



The construction of stables upon upper 

 floors, referred to in the last chapter, 

 may be carried out in two different ways ; 

 either by means of arches built in rings, of 

 brickwork in cement and springing from 

 rolled or cast-iron girders (the former are 

 now in most frequent use), or of rolled-iron joists bedded in 

 concrete, as previously described, the method now most com- 

 monly followed. 



In those erected for Messrs. Crosse and Blackwell's stables, 

 the former method was adopted. The brick arches, carrying 



Fig. II. 



Sills. 



Stables on 

 upper floors. 



