III. HISTORY. 355 



1816. Telescope of Torricelli, 



Royal Institute of " Studii Superiorly Florence. 



1817. Tube of TorricelU. 



Royal Institute of " Studii Superior if Florence. 



1818. Telescope of Divini. 



Royal Institute of" Studii Superiori" Florence. 



1819. Telescope of Mariani. 



Royal Institute of " Studii Superiori" Florence. 



1820. Telescope of Campani. 



Royal Institute of " Studii Superiori" Florence.. 



1821. Telescope by Amici. 



Royal Institute of " Studii Superiori" Florence. 



1822. Lens by Benedetto Bryhens. 



Royal Institute of" Studii Superiori" Florence. 



1823. " Frimo Mobile " of Ignazio Dante. 



Royal Institute of " Studii Superiori" Florence. 



1824. Quadrant of Cosimo I. 



Royal Institute of" Studii Superiori" Florence. 



1825. Quadrant of Giusti. 



Royal Institute of " Studii Superiori," Florence. 



1826. Compass of Antonio Blaichini. 



Royal Institute of" Studii Superiori" Florence. 



1827. Graphometer of Botti. 



Royal Institute of" Studii Superiori" Florence. 



1828. Registering Thermometer of Fontani. 



Royal Institute of" Studii Superiori" Florence. 



1829. Natural Magnet of the Accademia del Cimento. 



Royal Institute of " Studii Superiori" Florence. 



1830. Volume, Experiments in Natural Science Accademia 

 del Cimento. Royal Institute of " Studii Superiori" Florence. 



1831. Telescope, by Chr. Huygens. The objective ground 

 and polished by him, and bearing his signature. 



Professor Dr. P. L. Rijke, Ley den. 



Its focal distance is 3*906 m., and its opening 0-0616 m. The eye-piece 

 is composed of three convex lenses. The lens a, the nearest to the objective, 

 and the lens 6, following it, have a focal distance of 0' 105 m., and an open- 

 ing of 0'04 ; the lens c has a focal distance of 0*079 and an opening of 

 0'038 m. The distance between a and b is 0*212 m. ; that between b and c 

 0* 182 m. The eye should be placed at a distance of 0'058 from the lens c. 

 The lenses b and c serve only to rectify the images. 



Z 2 



