IV. On a new arrangement of binocular spectrum-microscope

The spectrum-microscope, as usually made, possesses several disadvantages: it is only adapted for one eye; the prisms having to be introduced over the eyepiece renders it necessary to remove the eye from the instrument, and alter the adjustment, before passing from the ordinary view of an object to that of its spectrum, andvice versâ ; the field of view is limited, and the dispersion comparatively small. I have devised, and for some time past have been working with, an instrument in which the above objections are obviated, although at the same time certain minor advantages possessed by the ordinary instrument, such as convenience of examining the light reflected from an object, and comparing its spectrum with a standard spectrum, are not so readily associated with the present form of arrangement.