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For cinema camera we use a normal Askaniawerke machine made to hold a 1 20 metre film. It moves on a vertical track placed above the microscope. A balancing weight permits of moving it up or down as desired. It also has a support which permits of it being used on its side, and its operation and placing in position of the film is very easy in this position. The vertical track on which the camera can be moved is attached by a strong spring, the tension of which can be regulated. By means of the tension in this spring, the bottom of the camera which bears on the spring does not carry the weight of the camera, and does not therefore transmit extraneous vibrations to the microscope. Again, in weak enlargements, that is when the illumination is sufficient, the aperture of the microscope can be placed directly on the film. In connection with this, there is in the back part of the camera a little aperture which in the normal position does not allow any light to reach the film, allowing at the same time the possibility of observing the picture as on a smoked glass screen when the rubber shutter of the aperture is displaced by the pressure of the eye.
The movement and rotation of the film in the camera are provided for by two different mechanisms. The first consists in a motor working cogwheels which allow of the movement being reversed. H and 2] "phe movement of the wheels is conveyed by means of inter-connected soft belts, one of which works the registering apparatus, 1^1 and the other a disc placed between the microscope and the lighting. Kl
Besides regulating the illumination, this second shutter has also the task of protecting the microscopic preparation against an excessive exposure to the light, only allowing the luminous rays to filter for the time necessary for each image. M In the latest machines of the Askaniawerke this filter consists of two discs, each of which has a round aperture of the diameter of the light ray. Between these two discs and operated by a motor, a third disc turns, one section of which forms an aperture capable of being regulated at will by means of a small lever.
A second lever permits the synchronization of the disc's movement with that of the exposure shutter of the camera. A filter can be placed in front of the apertures of the fixed discs or smoked glasses of various types. By means of change-speed gears, and without modifying the number of rotations of the motor, the movement of the two transmissions can be regulated from 16 photograms a second to two photograms a minute.
When the speed is less than 2 photograms a second, it is advisable to use instead of the procedure indicated, a machine which does not put into