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The final version of the Swift Universal Condenser is shown here, as offered in the 1910 Swift catalog. It has the polarizer housing again fitting to the bottom of the substage housing but the polarizer is on a hinge so it can be thrown out of the optical axis at will without the need to completely remove the housing from the substage. An additonal accessory is a frosted glass top element for the condenser to provide diffused light. In the illustration:
A. Is the optical portion.
B. Is the lever controlling the iris diaphragm.
C. Are the centering controls of the substage.
D. Is one of the two cell receptacles in the upper frame carrying two revolving cells, geared together by fine teeth, while the other is under the condenser, so that a revolving motion may be given to either by acting on the other; one of these can carry a mica plate, the revolution of which over the selenite films gives a great variety of color-tints with polarized light while the other serves to receive oblique light disks to which rotation can be given by the same means.
E. Is a revolving diaphragm with four apertures each of which can be fitted either with a series of three central stops for darkground illumination, or selenites for the polarizing apparatus.
F. Is the rotatable polarizing prism mounted on an eccentric arm so as to be brought under the axis of the condenser when not in use, and thrown out when not wanted.