Lighting Van Leeuwenhoek's samples.

Possible techniques for lighting opaque samples while using Van Leeuwenhoek microscopes have been tested, and the results are presented in relation to published material. The design of the microscope causes the sample to be in shadow with any form of top lighting. It is therefore suggested that Van Leeuwenhoek's hinted 'particular method of observing' might refer to a different style of microscope as shown in the frontispiece of the sale catalogue for his microscopes, and available at that time for purchase from sellers of optical equipment.