The picture, even when the highest powers are made use of, and the screen is at a distance of twelve feet from the apparatus, is of sufficient clearness and brightness to be available for demonstration to a large audience.
For the projection of lantern slides or of large section of tissue following parts of the apparatus are required: Lamp, condenser, cooler and bellows are the same as in the above described apparatus.
The stage and objective carrier are swung to one side.
The special-projection lens of 300 mm focal distance is to be used.
A slide carrier slips into the frame of the bellows, which is sufficiently large to accommodate lantern slides 9×10 and 9×12 cm in size. The slide carrier has a stop at both ends which facilitates its adjustment in the axis of the instrument, and is arranged for the simultaneous reception of two slides, so that while one is being projected it may be charged with a second which may then without delay be pushed into the optical axis as the first is removed. In this way series of pictures may be thrown on the screen without interruption.
When so arranged the projection can be made upon a screen 30 feet from the apparatus, over the heads of an audience.
Prices:
| No. 117. | Projection-lamp for current of 20 Ampères, with centering arrangement | $92.— |
| Fixed rheostat | $30.— |
(The same, adjustable $45.—.)
Lamp and rheostat are furnished at factory prices. In ordering it is well to state the strength of the available electric current, also whether it is constant or alternating.