750 



Transactions of the Society. 



XXII. — On an Improved Finder. By W. Webb. 

 (Bead Uth April, 1880.) 



The finder wliicli I bring before the Society this evening consists 

 of a square having sides of f inch, and divided into 22,500 smaller 

 squares with sides the -^ho of an inch (enclosing a space therefore 

 equal to the toftt^ of an inch), being 20,000 more squares than 

 the Maltwood finder, which is an inch square. The lines are ruled 

 by a diamond upon the under side of the thin cover-glass (for 

 better use with higher powers), and are filled in with black, the 

 field being transparent. 



One square of the Maltwood finder more than covers the field 

 with a ^-inch objective and A eye-piece, all the corners of the squares 

 being out of the field ; but in the new finder there are sixteen 

 squares in the same space as one in the other. 



Fig. 71. 



With some of the higher powers, it is not incorrect to say that 

 it is absolutely impossible to use the ordinary finder, because (1) 

 being a photograph an inch on each side, it is necessarily so very 

 coarse that when used with the high powers the image as a whole 

 is destroyed in consequence of the separation of its component 

 grains of silver ; and (2) all specific trace of locality is absolutely 

 lost by the great size of the squares. 



