TURNTABLES. 281 



the slide, when clasped between them, must be perfectly 

 centered. 



In 1879, Mr. Rolfe re-invented Kinne's turntable, and 

 described the same before the members of the Quekett 

 Club, adding at the same time an idea of his own, which 

 was quite novel, and is illustrated in Fig. 234. 



FIG. 234. 



The year 1880 saw the introduction of two turntables, 

 the first by Mr. Dunning (Fig. 235), which has since 

 been made by Mr. Swift, and the second introduced by 

 Dr. Matthews. Mr. Dunning's turntable will take any 

 slides up to two inches in width, and also serves for 

 retouching slides, the circles upon which are not truly 

 central. Dr. Matthews' last production is to be found 

 fully described in the ' Journal of the Royal Microscopical 

 Society,' and as it only consists of a method of driving 

 the table, it will be of but little use mentioning it here in 

 detail. 



Another good form of self-centering turntable has lately 



