Gould's Improved Pocket Simple & Compound Microscope by Cary, 1835
This is the small version of a class of toy microscopes designed by Gould and made by Cary. William Cary was a very popular London microscope maker in the late 18th century. By 1821, Cary was established at 181 Strand, London, his two nephews now also working out of this shop ultimately taking control of the business after his death in 1825. One of his employees, Charles Gould, eventually designed this well-known type of "pocket microscope". The microscopes are compact and fold into their small mahogany cases, which also serve as the base for the opened instrument. These microscopes were very popular, as evident by their abundance today.
Though interesting in their concept and design, the Gould-type microscopes were completely unimportant in terms of the advance of science and field microscopy, being too delicate for professional use, having low magnifications and suffering from severe spherical and chromatic aberrations. But due to their relatively low prices, they had their role in advancing the awareness of the ability to take a compound microscope out to the open.
From the accompanying booklet: "This microscope... has been found, upon comparison, by several scientific gentlemen, superior in power to, and more distinct, than many of the larger and more expensive instruments of the kind. It shuts up in a case, three inches by three and a half, and may be carried in the pocket without the slightest inconvenience."