H. L, Smith on a new Binocular Eye-piece. 45 
measured, I find to be only (03™™, and when placed about half 
a meter from the eye, and three meters from the sash of a win- 
will vary wi 
trial. Fig. 1 
represents in section this form ; ab is the glass pl ote 
transmitted, and d the reflected ray. The cap of the eyepiece 
