92 THE BOOK OF THE LANTERN. 



of water. The size while on the fire should be watched 

 and occasionally stirred, but should not be allowed to boil. 

 When melted, this size is well brushed into the calico, and 

 allowed to dry. It will then be ready to receive its 

 coating of white paint. This consists of whiting which 

 has been soaked in water until it assumes the appearance 

 of thick white mud. To this strong melted size must be 

 added until the mixture is of the consistence of cream. 

 It can be left now for some hours until it has become 

 perfectly cold. At the end of that time it should have 

 the appearance of very weak jelly, a jelly which can be 

 easily broken up by the paint brush. 



The frame being placed upright and properly secured, 

 the workman commences at the top, working the well- 

 charged brush up and down, and then horizontally, so as 

 to avoid leaving any lines upon the surface, until it is all 

 covered. If the sheet be unusually rough in texture, it 

 will benefit by another cqat when the first is dry. 



When this painting operation is finished the nails must 

 be drawn from the frame, and the sheet must be tacked 

 on to a roller. This roller may be hung like a window- 

 blind at the top of the room, and governed by a cord in 

 the familiar manner. But if it is of large size, say 12 

 feet across or more, the roller is best placed at the bottom 

 of the sheet, and made to roll up by cords upon its pro- 

 jecting ends, and pulleys above like the drop scene at a 

 theatre. 



It has often struck me as a deplorable oversight that 

 halls where lantern lectures are of constant occurrence, 

 are not fitted with permanent roll-up screens of this kind. 



