Projection Apparatus (1917)

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Bausch & Lomb Optical Company- Adjustable Slit An adjustable slit is an indispensable attachment in spectrum experiments with light. We furnish the adjustable slit mounted on a blackened metal front board, which may be attached to the standard in such a way as to make the slit horizontal or vertical, as desired. The plates of the slit, which are of German silver, with edges carefully ground and polished, form two sides of a parallelogram. They are adjustable by means of a micrometer screw, with a pitch of .5 mm, and a spring, producing a very gradual movement. All the bearings and fittings, as well as the edges, are precisely made, giving unusually high grade results whenever this slit is used. Prisms Prism Support This is a convenience in experiments with light, affording a support for the different prisms, etc. It has a regular standard with base block and clamp, which attaches directly to the optical bed and may be placed in any convenient position along it. It is of metal throughout. The top is circular, 75 mm in diameter, and is adjustable for height, a convenient clamping screw securing it in any desired position. 122