SLIDES, CARRIERS, AND EFFECTS 139 



occasions this is an advantage, but the panoramic carrier has 

 no other merit in my opinion. 



If different sizes have to be shown in the same lecture, the 

 best carrier is probably that known in the trade as Beard's 

 self-centering carrier, shown in fig. 73. Whatever be the 

 size of the slide, it has only to be placed upon the brass runner 

 at the bottom and pushed up till it stops, and it will be in the 

 centre of the stage. 



The best and simplest carrier for any single lantern, or 

 bi-unial, is, in my own opinion, the simple one shown in fig. 74, 

 but it is only possible for slides of uniform size. There are 

 two grooved frames with openings at the top, into which slides 

 can be dropped, the two combined sliding freely from side to 

 side in an outer frame which remains immovable in the stage. 



Fia. 74. Double Carrier 



There is a stop at each end, so that when the inner frames 

 are pushed up to either end, one frame is centered. The slide 

 done with is out on one side, and can be lifted out by the 

 fingers and the next one dropped in, at any convenient moment. 

 Once dropped in it is ready, and a push in changes the slide 

 in an instant. To prevent the dropping in of the slide making 

 any noise, it is well to jam in a narrow strip of india-rubber 

 (flat] on the bottom of the bottom groove. 



This carrier is an especial comfort to the scientific lecturer, 

 especially if he has himself to stand near his lantern, as often 

 happens. The assistant has only to concern himself to have 

 the next diagram ready in the frame not in use ; and can then 

 bring it on in place of the other in the twinkling of an eye, or 



