GRAND VAN HEURCK MICROSCOPE (Holos Oil Immersion Condenser)

The 'Holoscopic Oil Immersion Condenser' is suitable for use with the highest power objectives and has an immersion front which may be removed for use with dry objectives of medium to high power. It is signed: 'HOLOSCOPIC OIL IMMERSION CONDENSER , W. Watson & Sons L^td London' and also: 'n.a. 1.30, 3843'.  This condenser fits the same condenser housing as the 'Aplanatic Low Power Holos' Condenser. The condenser mount is also signed 'W. Watson & Sons London'.   A later version of the Holos Oil immersion condenser with the Circuit Stage Van Heurck microscope has a larger diameter and fits a different mount. Both condenser mounts have a nice iris diaphragm and a swing-out filter holder, that is of diameter suitable for stops supplied.   In addition to darkground stops and oblique illumination stops, a 'Dark Ground Illumination Expanding Stop (aka Travis stop) also fits the swing-out filter holder of this condenser mount.    There are several inserts for the filter holder which sits below the optical elements. These include a variety of blue and blue-green filters, a frosted glass light diffuser, 5 stops for darkfield lighting, and 6 inserts for various types of oblique illumination. There is also a centering insert. This filter holder has knurled edges and is rotatable which is handy for directing the oblique illumination from different directions.