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Bausch & Lomb Optical Company Home Balopticon Figure 1—Home Balopticon, Simple Form for Projection of Opaque Objects Only- Interior View, Showing Reflecting Mirrors and Watch on Object Holder. This Balopticon has been designed to meet the popular demand for a really efficient, but inexpensive instrument, for the projection of post cards, photographs and similar objects in the home, the small classroom and the Sunday school room. It is meeting the popular demand in a most satisfactory manner and is also proving an excellent instrument for small schools that are unable to purchase more elaborate or expensive equipments. It is so simple in operation that any child can operate it, yet it far excells the ordinary post card projector in the quality of the picture produced, the illumination and its wide range of usefulness. The apparatus is made in two forms: for the projection of opaque objects only and in combination form for the projection of opaque objects and lantern slides as well. In the latter model the interchange between the projection of opaque objects and of lantern slides is instantaneous, being effected by simply turning a convenient lever on the outside of the dark chamber. This lever operates an in- terior shield which cuts off the light from the lens for either form of projection not desired at the time. One of the great advantages of this apparatus is that the object holder occu- pies a horizontal position against the floor of the dark chamber, rather than in the wall, as is the case with the ordinary post card projector. This permits solid objects of all kinds, such as coins, curios, etc., to be laid on the object holder and pro- jected on the screen, while any part of a magazine can be shown without trimming or in any way mutilating it. Further, this arrangement makes the changing of opaque specimens by the operator more convenient. A single interior mirror brings the image always into correct position, from left to right, on the screen, so that reading matter appears unreversed—another strong feature. The lenses are of achromatic construction, designed to give maximum illumination and a flat field. These lenses project a picture that is clearly defined to the extreme margin. The illumination is furnished by one of the new gas-filled Mazda lamps of 400-watt capacity. With this lamp and the use of a special, accurately corrected optical mirror, we are able to secure 47