MELLONI, MACEDONIO (1798-1854)

This article appears in Volume V18, Page 96 of the Encyclopedia Britannica.

Encyclopedia Britannica - Main :: MEC-MIC

MELLONI, MACEDONIO (1798-1854) , Italian physicist, was born at Parma on the

lath

LATH (0. Eng. laett, Mid. Eng. lappe, a form possibly due to the Welsh llath; the word appears in many Teutonic languages, cf. Dutch lat, Ger. Latte, and has passed into Romanic, cf. Ital. latta, Fr. latte)

of April 1798. From 1824 to 1831 he was professor at Parma, but in the latter year he was compelled to escape to France, having taken

part

PART

in the revolution. In 1839 he went to Naples and was soon appointed director of the

Vesuvius

VESUVIUS (also Vesevus in ancient poets)

observatory

OBSERVATORY

, a post which he held until 5848. Melloni received the Rumford

medal

MEDAL (Fr. medaille, from Lat. metallum)

of the Royal Society in 1834. In 1835 he was elected correspondent of the Paris

Academy

ACADEMY, GREEK
ACADEMY, ROYAL

, and in 1839 a .foreign member of the Royal Society. He died at Portici near Naples of cholera on the

lath

LATH (0. Eng. laett, Mid. Eng. lappe, a form possibly due to the Welsh llath; the word appears in many Teutonic languages, cf. Dutch lat, Ger. Latte, and has passed into Romanic, cf. Ital. latta, Fr. latte)

of August 1854 Melloni's reputation as a physicist rests especially on his discoveries in radiant heat, made with the aid of the thermomultiplier or combination of thermopile and

galvanometer

GALVANOMETER

, which, soon after the discovery of thermoelectricity by T. J. Seebeck, was employed by him jointly with L.

Nobili

NOBILI, LEOPOLDO

in 1831. His experiments were especially concerned with the power of transmitting dark heat possessed by various substances and with the changes produced in the heat rays by 'passage through different materials. Substances which were comparatively transparent to heat he designated by the

adjective

ADJECTIVE (from the Lat. adjectives, added)

" diathermane," the property being " diathermaneite," while for the heat-tint or heat-coloration produced by passage through different materials he coined the word " diathermansie." In English, however, the terms were not well understood, and " diathermancy," was generally used as the equivalent of " diathermaneite." In consequence Melloni about 1841 began to use " diathermique " in place of " diathermdne," " diathermasie " in place of "diathermaneite," and " thermocrose " for " diathermansie." His most important book, La thermocrose au la coloration calorifique (vol. i., Naples, 1850), was unfinished at his death. He studied the reflection and polarization of radiant heat, the magnetism of rocks, electrostatic

induction

INDUCTION (from Lat. inducere, to lead into; cf. Gr. ilrayu yli)

, daguerrotypy, &c.

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