This portable Ellis-type microscope is a simple and portable device. Made according to the model described in 1755 by John Ellis (1707-1776). It was called a botanical or aquatic microscope and was very popular. This device is one of the largest of its kind ever made. It measures 21 cm and the case in which it is housed 22 x 12 x 9 cm. It contains five eyepieces and three objectives of different magnifications.

This model was used in various scientific expeditions. It is practically the same as the one designed by Robert Banks and used by Joseph Hooker, Darwin’s mentor. With this microscope Robert Brown described «Brownian motion» and the characteristics of the cell nucleus and it was used by Charles Darwin on his voyage on the Beagle in 1830.

Another similar botanical microscope model was described by G. R. Raspail in 1830 in France.