284 



Transactions of the Society. 



Fig. 72. 



Fig. 73. 



sprung in a manner still used by Powell, not only for apparatus of 

 this kind, but also for his jointed mirror arm. This method, shown 

 in fig. 75, is very simple and most efficacious ; the pivot, 

 which is carried through the plate holding it, is grooved, 

 and a flat spring with a U-shaped nick in it slips into this 

 groove. I have an old Microscope by Powell, dated about 

 1840, in which the mirror, stage forceps, stage bull's- 

 eye, &c, are all sprung in this manner ; and although it 

 |j is some sixty years old, its moving parts act in the 



smoothest way possible. 

 On examining the plates in the Transactions of the Society of 

 Arts, published both before and after this time, we find that a num- 

 ber of them were drawn by 0. Varley and engraved by 

 E. Turrell. Varley lived at 1 Chirles Street, Clarendon 

 Square, Somers Town, and Edmund Turrell was, we learn, 

 an engineer and engraver at 46 Clarendon Street. On 

 February 14th, 1832, Turrell published in the Trans- 

 actions of the Society of Arts,* an account of his well- 

 known Microscope-stage, which was at first, and for a 

 long time subsequently, made only by Powell. This is 

 still the best ever designed, and is largely used at the 

 present time ; so we see that these two men not only 

 lived in the same neighbourhood as Powell, but also 

 gave their attention to Microscope construction. The 

 question naturally arises, who was the author of all this 

 springing in the Microscope ? It is impossible to say 

 what influence Turrell had in the matter, because he pro- 

 bably died shortly after his invention of the mechanical 

 stage, as his name disappears from the plates in the 

 Society of Arts' Transactions, and in 1838 we learn that 

 he was dead. Varley certainly was the first microscopist 

 t) appreciate and record the great value of springing 

 every movement in a Microscope ; he was himself a good 

 mechanic, and had just previously designed a special lathe 



Fig. 74. 



lf"~l 

 1 !■] 



JL 



for lens work ; moreover he must have acquired a large experience of 

 mechanical appliances from the great number of plates he had drawn. 



• Vol. xlix. p. 113, pi. 4(1833). 



