GRAND VAN HEURCK MICROSCOPE (Parachromatic Condenser and Housing)

The Watson Parachromatic condenser was first made about 1896, and was one of their best, surpassed only by the 'Holos Oil Immersion" condenser and the Apochromatic condenser by Powell & Lealand which they also sold.

This condenser is shown with an unusual housing in which the optical elements can be quickly removed via a slider and another used in its place if needed, though only one slider accompanied this instrument. This slider mechanism as used for the nosepiece is known as a Sloan objective changer and its use as a condenser changer also appears in the more modern Swift Symposium Microscope formerly in this collection. I could find no Watson entries for this condenser housing, and it is unsigned. The swing-out stop- or filter-holder rotates.