This tiny microscope gives its name to a type known as "minerals" or "furnace". It is housed in a 10.5x6x5 cm mahogany box and its base is conical in shape, so that it can fit into the slot in the box to give it stability. Although it seems incredible, it has all the necessary elements for its correct use and in fact allows observations of small preparations (5.5x1.5 cm), some of which are preserved inside. In the working position, its height is 9 cm.
References: "Billings Microscope Collection" pag 36, fig. 69
"Billings Microscope Collection" pag 43, fig .81
H. Moe, "The Story of the Microscopes", pag 189