Simple aquatic microscope consisting of two profiled brass plates joined at their ends; between the plates is a hinged cross stage that rotates into position in front of the aperture formerly containing a lens, now missing. The microscope is fitted with a rotating disk with four round apertures, in front of which a forceps or spike can hold the specimen for observation. The instrument is housed in a wooden case covered in black leather and lined with velvet. There are a few accessories, including a slide carrier and a forceps. This type of microscope was invented by Christiaan Huygens. The instrument is signed Chapotot, not enough evidence to establish whether it was made by Louis Chapotot or his son.