THE LIME-LIGHT 



57 



base-line A B. But when the bags have worked down as in 

 fig. 85, the weights are farther back in proportion, and so 

 far as the back edge of the bottom board is concerned, over- 

 Jiang the base. If this is not provided for, the weights may 

 therefore tip up the whole concern backwards, and roll off, 

 when there will be sudden darkness and a serious fright, 

 though no further accident could happen unless there had 

 been mixture in one of the bags ; if there had, of course the 

 removal of pressure would produce an immediate explosion. 

 I never heard of this latter happening ; but of the other I 

 have, and it is unpleasant enough. 



The boards must therefore be let down on the floor when 



A q 



G A 



FIG. 



Fio. 35 



the bags are about half emptied, or else the ' base ' must be 

 so lengthened behind the back of the bottom board, as to 

 guard against all danger. It is quite easy to do either. 

 Solid boards are generally made without any separate base, 

 for simplicity, a support being hinged to the front at A, fig. 36, 

 which may be a pair of light legs with a connecting strip. 

 Then a stretcher-bar, s, may be hinged near the back end of 

 the lower board at B, resting on the cross-piece connecting 

 the two legs ; and if a hole in the end of the stretcher drops 

 over a wire pin projecting from the cross-piece, at c, it is 

 impossible for the legs to slip from under the boards. When 



