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Bausch & Lomb Optical Company Figure 6—Vertical Attachment No. 4290 for Model D Balopticon. Vertical Attachments For the projection of transparent objects which must be maintained in the horizontal position two attachments are available. The one illustrated in Figure 6 is attached to the slide carrier support by removing the bellows and substituting in the sliding ways the prism-shaped metal box which contains a reflecting mirror. The vertical bed is attached to the slide carrier support by two strong screws. The front standard of the Balopticon carrying the pro- jection lens is removed and placed on the vertical bed together with a mirror which fits over the lens hood. The third condensing lens in mount is removed from the back of the slide carrier support and placed over the opening in the top of the prism box. It not only converges the light on the projection lens, but, the plane side of the condenser being uppermost, it serves as a stage, 4/4 inches in diameter, upon which the glass dishes, specimens, etc., to be projected are placed. The second type of vertical attach- ment, shown in Figure 7, is far more con- venient and affords a much wider range of usefulness because one can change instantly from projection with this attachment to the use of lantern slides, and vice versa. Consequently the attachment may be left in position on the lantern as long as any other work undertaken does not require the addi- tional space on the optical bed occupied by the vertical attachment. The instrument has a dark cham- ber supported by two standards which fit the optical bed and are provided with clamps. Within this dark chamber is the reflecting mirror, controlled by an exterior lever as shown in the illustra- tion. When the mirror is dropped to the 45° angle, it reflects the light up Figure 7—Vertical Attachment No. 4136B through the vertical attachment. When * or ® Balopticon. the mirror is turned up, it covers the condenser of this attachment, permitting an 43