THE LIME-LIGHT 45 



pattern is used, as shown in fig. 26, which speaks for itself. 

 It is only necessary to say, in case a pair of boards is home- 

 made, that the pair must not come closer at the hinges than 

 half-an-inch apart, to 

 allow for the thick- 

 ness of the bag when 

 flattened. If this is 

 not attended to, the 

 boards will not shut, 

 or use the last por- 

 tion of the gas. In FlQ> 26 _ Bag in use 

 case of an emergency, 



a bag has been ere now laid on the floor, and a black-board, 

 or the ends of a couple of reversed forms, hinged down to 

 the floor by two pairs of staples or hooks driven into floor 

 and board respectively. 



25. Tubing. The best soft grey or red vulcanised tubing 

 should be used; common harsh grey, or cheap red, spoils 

 very soon. Tubing with spiral wire inside must be scrupu- 

 lously avoided ; the wire soon rusts, breaks, and chokes and 

 perforates the tubing. There should be a clear ^ bore for 

 oxy-calcium jets, and not less than f for high-pressure jets. 

 The ordinary ' stout ' thickness answers, but successive coilings 

 after use generally twist and kink it up after a bit, especially 

 the red. For anything like regular use, therefore, the cheapest 

 in the end is good soft tubing of best quality and double thick- 

 ness. Fig. 27 is an exact section of what I use. 

 It is more than double the price of the common 

 tube, owing to the weight of material ; but 

 there is immense wear in it, it never kinks, 

 and it may be slipped on a nozzle in any posi- 

 tion without choking the bore at a bend. 27 



Occasional extra long lengths of tubing are 

 joined up by slipping the shorter pieces over the ends of a 

 few inches of brass tube. All such pipes and nozzles should 



