A VISIT TO AN OBJECTIVE FACTORY. 23 
ed Sept Ee 
Here we hada lens formed for us from the rough glass. A 
piece was examined as to freedom from flaws, and next cemented 
with best black sealing-wax to the chuck of the lathe. It was 
then turned to shape with a small, smooth-cut file moistened with 
oil of turpentine, used as a turning tool. When this stage was 
reached, the partly constructed lens was polished and finished by 
setting the polishing lap running in the lathe and working the lens 
upon it by hand—attached as it was to the chuck upon which it 
was fashioned. 
This is the way in which most small lenses are made, and it 
will be seen that their manufacture calls for a large amount of 
manipulative skill on the part of the operator. 
In another room we saw the brass work being executed, both 
for the objectives and their boxes. We also saw some of the 
mechanical arrangements for expediting the work, and one, especi- 
ally, for cutting a spiral slot for the cover adjustment struck us as 
being very ingenious. 
We now came to the mounting department where the lenses 
were tested and placed in their brass cells, and the exceedingly 
simple methods which practical opticians have of setting and 
centering these lenses greatly excited our admiration. The reflec- 
tion of the window bars and the flame of the lamps over which the 
lenses and cell were warmed before mounting, were each pressed 
into service as an aid to centering. The lens by which Mr. Wray 
illustrated to us the mounting process was a low angle half-inch, 
for use with the binocular, composed of two pairs of lenses with a 
thick, solid front. 
The brass work and lenses of the back pair being warmed, a 
drop of balsam was placed upon the anterior surface of the back 
lens. Both were then placed in the cell and screwed into the 
lathe chuck, being pressed together and manipulated with a pointed 
pencil of soft wood until the reflected image of the flame was quite 
steady upon the revolving glass. The middle combination was 
then treated similarly, the front screwed on, and finally the aberra- 
tions corrected by reducing the thickness of the front. 
Before leaving we inspected several of Mr. Wray’s glasses, one 
of which notably, a +45, gave us really a splendid show of the Podura 
scale when used with a deep eyepiece. 
Mr, Wray makes a separating lens in which the two systems 
are moved by a screw collar in a manner similar to that made by 
Zeiss of Jena, but we believe that Zentmayer was the first to pro- 
duce objectives of this pattern. ; 
Since visiting Mr. Wray’s factory we have had many of his ob- 
jectives under our notice, sent into our Verification department, 
and it is mainly on this account that the present article has been 
written, as we have been very much pleased with his productions. 


