INDEX 1788 : V.II.321

Pes ligneus, qui sex, vel septem Prismata commode sustentare potest.

A wooden stand capable of holding six or seven prisms.

This accessory, where seven prisms can be stored, could also be used to study the of the dispersion of light by a prism. It was used for experiments like those for which instrument 91 was used. The two items of apparatus differ in that this one allows the prism used in the experiment to be placed at one of seven different heights whereas the stand used for instrument 91 enables the height to be changed continuously, and is thus more useful.

From Colégio dos Nobres, catalogue n.º 311.

's Gravesande, Willem Jacob, Physices Elementa, Leiden, 1742, Vol. II, § 3480, Tab. CX, fig. 7 and § 3524, Tab. CXII.