It is a microscope of barrel (barrel) or system of drum (Drum). This simple microscope system was introduced by Oberhauser in 1835. Many models were made of it, but in reality only with minor variations.
It is possibly the most popular and cheapest type of microscope that was made when microscopes were small gadgets to satisfy the curiosity of an educated public and not yet used as a research instrument and for diagnostic purposes, as in the 20th century.
The size of this microscope is 155mm high and the base has a diameter of 50mm. This model, from an unknown manufacturer, has three interchangeable lenses of different magnifications.