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ACORN MICROSCOPE COMPENDIUM:
c. 1790, unsigned
DESCRIPTION
This is the central instrument of an 'Acorn' microscope compendium. The fleaglass allows one to trap an insect or examine some pond water inside and observe its behavior under magnification. The device consists of a cylinder which is approximately 18 mm high and 18 mm in diameter. It has a very slight taper, fitting inside the loupe perfectly. Both the top and bottom have narrow knurling around the edge to facilitate removal of those elements. About 6mm from the bottom of this little cylinder is a seam. When the bottom third of the cylinder is unscrewed, it reveals a flat glass in its bottom and a concave glass remaining in the upper portion, facing downward. This arrangement of a concave disk covered by a flat piece of glass is very reminiscent of the arrangement of the 'wet cell' type of live box supplied with my screwbarrel microscope, except that this is a single cell. The focal length of the optical element of this little cylinder is such that only an object between these two pieces of glass, is in focus. The lens for the fleaglass is held in place by a small brass dome, much like the lenses are held in the eyepiece components of a screwbarrel microscope.
