See also:

• ACTINOMETER (Gr. locals, ray, ,arpov, measure)

ACTINOMETER (Gr. locals, See also:

• RAY (Lat. raia)
• RAY (or WRAY, as he wrote his name till 1670), JOHN (1628-1705)

ray, ,arpov, measure)  , an See also:

• INSTRUMENT (Lat. instrumentum, from insincere, to build up, furnish, arrange, prepare)

instrument for measuring the See also:

• HEATING

heating and chemical effects of See also:

• LIGHT

light . The name was first given by See also:

• SIR

Sir See also:

• JOHN
• JOHN (1167–1216)
• JOHN (1290-c. 1320)
• JOHN (1296-1346)
• JOHN (1371–1419)
• JOHN (1468-1532)
• JOHN (1801-1873)
• JOHN (Heb. llni')
• JOHN (ZAPOLYA) (1487-1540)
• JOHN, 4TH MARQUESS OF TWEEDDALE (c. 1695-1762)
• JOHN, DON (1545-1578)
• JOHN, DON (1629–1679)
• JOHN, GOSPEL OF ST
• JOHN, or HAYS (1513–1571)
• JOHN, THE APOSTLE
• JOHN, THE EPISTLES OF

John See also:

• HERSCHEL, CAROLINE LUCRETIA (1750-1848)
• HERSCHEL, SIR F
• HERSCHEL, SIR FREDERICK WILLIAM (1738-1822)
• HERSCHEL, SIR JOHN FREDERICK WILLIAM, BART

Herschel to an apparatus for measuring the heating effect of See also:

• SOLAR, SOLLER (Lat. solarium, Fr.• galetas, Ital. solaio)

solar rays (Edin . Journ . See also:

• SCIENCE (Lat. scientia, from scire; to learn, know)

Science, 1825); Herschel's instrument has since been discarded in favour of the pyrheliometer (Gr. aGp, See also:

• FIRE (in O. Eng. f j'r; the word is common to West German languages, cf. Dutch vuur, Ger. Feuer; the pre-Teutonic form is seen in Sanskrit pu, pavaka, and Gr. irup; the ultimate origin is usually taken to be a root meaning to purify, cf. Lat. purus)

fire, ijXios, See also:

• SUN
• SUN (0. Eng. sonne, Ger. sonne. Fr. soleil, Lat. sol, Gr. ijXior, from which comes helio- in various English compounds)

sun) . (See See also:

• RADIATION, THEORY OF

RADIATION.) The word See also:

• ACTINOMETER (Gr. locals, ray, ,arpov, measure)

actinometer is now usually applied to See also:

• INSTRUMENTS

instruments for measuring the actinic or chemical effect of luminous rays; their See also:

• ACTION

action generally depends upon photo-chemical changes (see PHOTO-See also:

• CHEMISTRY
• CHEMISTRY (formerly "chymistry"; Gr. xvµela; for derivation see ALCHEMY)

CHEMISTRY) . Certain See also:

• PRACTICAL

practical forms are described in the See also:

• ARTICLE (from Lat. articulus, a joint)

article See also:

• PHOTOGRAPHY (Gr. bias, light, and ypa w, to write)
• PHOTOGRAPHY, CELESTIAL

PHOTOGRAPHY .