Conical tube of sheet-metal painted the color of wood, mounted on a three-wheel wooden stand, and equipped with altitude motion. The tube was part of a telescope devised by Giovanni Battista Donati, director of the Specola at the Museum of Physics and Natural History of Florence and founder of the Arcetri Observatory. The burning lens by Bregans (XI.5) constituted the objective. The focus of the lens accommodated a prism spectroscope built for the purpose by Giovanni Battista Amici.