ray-filter

Quenching the light by the ray-filter at F, and placing the pile at P, the totally reflected heat-beam is immediately felt by the pile, and declared by the galvanometric deflection.

Six Lectures on Light Delivered In The United States In 1872-1873 John Tyndall 1856

Cutting off the light by our ray-filter, and exciting the magnet, the needle is instantly deflected, proving that the magnet has opened a door for the heat, exactly as in Faraday's experiment it opened a door for the light.

Six Lectures on Light Delivered In The United States In 1872-1873 John Tyndall 1856

Possessed of this instrument, of our ray-filter, and of our large Nicol prisms, we are in a condition to investigate a subject of great philosophical interest; one which long engaged the attention of some of our foremost scientific workers -- the substantial _identity of light and radiant heat_.

Six Lectures on Light Delivered In The United States In 1872-1873 John Tyndall 1856

Marking the places of the light-images, we introduce between N and L our ray-filter (not in the figure) and quench the light.

Six Lectures on Light Delivered In The United States In 1872-1873 John Tyndall 1856

At present the possession of our more perfect ray-filter, and more powerful source of heat, enables us to pursue this identity question to its utmost practical limits.

Six Lectures on Light Delivered In The United States In 1872-1873 John Tyndall 1856

Interposing between the lamp (A) and the first prism (B) our ray-filter, the light previously transmitted through the first

Six Lectures on Light Delivered In The United States In 1872-1873 John Tyndall 1856

Introducing our ray-filter, the thermo-pile, playing the part of an eye as regards the invisible radiation, receives no heat when the eye receives no light; but when the mica is so turned as to make its planes of vibration oblique to those of the polarizer and analyzer, the heat immediately passes through.

Six Lectures on Light Delivered In The United States In 1872-1873 John Tyndall 1856

Cutting off the light by the ray-filter, and placing at the focus a thin sheet of platinized platinum, the invisible rays declare their presence and distribution, by stamping upon the platinum a white-hot image of the carbons.

Six Lectures on Light Delivered In The United States In 1872-1873 John Tyndall 1856

This ray-filter is a liquid, black as pitch to the luminous, but bright as a diamond to the non-luminous, radiation.

Fragments of science, V. 1-2 John Tyndall 1856