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Bausch & L o m b Optical Co m p a n y Microscope Accessories for Polarized Light For the projection of petrographical specimens, crystals, etc., we have designed a set of accessories for projection with either parallel or convergent polarized light. The accessories can be used with either the Horizontal or Combined Horizontal and Vertical Type of our Large Projection Microscope. This set of accessories is made up of the following:— Nicol prism polarizer in mounting to fit on the back of the substage condenser, and so mounted that there is no danger of overheating by the arc. Nicol prism analyzer in rotating mount which clamps over eyepiece of microscope and which can be thrown in or out of the optical axis. The mount- ing is provided with a slot for insertion of selenite plates, quartz wedges, etc. Supplementary draw tube which is attached to the revolving plate in place of one of the eyepiece adapters. This tube is required in the projection of interference figures to bring the Bertrand lens into correct position. 48 mm achromatic objective which is attached to above draw tube and serves as Bertrand lens in projection of interference figures. Substage condenser of high numerical aperture to be mounted on substage nosepiece in place of small condenser for projection of interference figures. An objective of correspondingly high numerical aperture, such as a 4 mm, must be used in this work. Circular revolving stage on plate to fit in microscope stage in place of plate carrying water cell. 115