XXII INTRODUCTION. 



Part Secern^, so tnat customers looking for the most beauti- 

 ful effects, without being restricted to a specific programme, 

 will do well to consult these choice selected lists. 



Plain slides are now more frequently called for than 

 those colored and mounted in wood, not only because they 

 are cheaper, but because they are really quite in the 

 fashion. 



Most of the plain or glass slides in market are in one or 

 other of three shapes, viz. : 



1. Views of interest in America, produced by Ameri- 

 can photographers, are mostly made on quarter plate 

 B. P. C. glass (best polished crown glass, three and 

 a quarter by four and a quarter inches). This gives 

 to the sides of the three-inch pictures a margin of fully 

 half an inch for labels and for handling. The Woodbury 

 and the Scientific Sciopticon Slides are also of the same size 

 and shape. 



2. The French slides are but four inches wide, the quar- 

 ter of an inch being taken from the picture, and they are 

 of thin glass. They are extensively used, and the best of 

 them are doubtless the best in the maiket. 



3. The English slides have also a smaller picture, with 

 just margin enough all round for binding, making the 

 whole three and a quarter inches square. They are apt 

 to fail of covering the full opening in the slide carrier ; 

 the name has to be stuck on the edge, and there are twice 

 as many ways of getting it on to the screen in a wrong 

 position. 



The Scientific Sciopticon slides are the most uniformly 

 good for their purpose, and are put at the low price of 

 thirty. cents each, or twenty-five cents each by the set, to 

 insure their being introduced so extensively as to be manu- 

 factured to advantage. French slides are here reduced to 

 sixty cents each, and the most of others to fifty cents. 



