BRICKWORK. 99 



covered with tarpaulins, which quantity should be used first. A space, 

 twelve feet by ten feet, and three feet six inches deep, will hold ten tons of 

 coal. 



In the example just referred to, the spaces were divided into three, by pas- 

 sages five feet wide, the entire length of the store being seventy feet ; the 

 spaces for the coal were fifteen feet by twelve at each end, and one thirty feet 

 by twelve in the centre : 200 tons could be stored with convenience. When 

 full, the stacks must be retained by three-inch planks, placed vertically and 

 strutted, spaces being.left to work the coal. 



As a check upon the delivery and use of the coal, the walls of the stores 

 should be marked at certain heights corresponding to five or ten tons. 



The adjoining cut (Fig. 21.) represents a retort-house built of brick, upon 

 the most simple construction, and well adapted for a town requiring 70,000 

 cubic feet of gas for the supply of each night in the winter season. Being 

 without coke-cellar, the charges must be drawn into wrought-iron barrows, 

 the contents wheeled into the open air, and spread abroad to cool. 



The outside walls are calculated to give the greatest security with the least 

 possible material. The piers a a, are eighteen inches thick at the base, pro- 

 jecting 4^ inches (on the outside) from the brickwork filling the space be- 

 tween them. Half-way up the walls there is a 4^-inch offset, which leaves the 

 thickness of the panels fourteen inches below, and nine inches above the 

 offset. 



The roof is of wrought-iron, covered with common pantiles. The ventila- 

 tor is of wood. 



The estimate for this house, including a chimney seventy feet high from the 

 ground-line, was 550. The cost of the ovens for the reception of the retorts, 

 eight in number, was 57, and the setting of the retorts cost 103. 



The retorts were set five in one oven, making forty retorts ; which will allow 

 two extra benches for repairs. 



In twenty-four hours, thirty working retorts will carbonize 240 bushels, or 

 180 cwt. of coal, and produce 78,000 cubic feet of gas. In some places where 

 little gas is required in the summer season, one half or even the entire num- 

 ber of retorts may be set three to one oven with ceconomy. 



o2 



