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McLennan, Sir John Cunningham

(Encyclopedia)McLennan, Sir John Cunningham, 1867–1935, Canadian physicist, grad. Univ. of Toronto (B.A., 1892; Ph.D., 1900). He taught at the Univ. of Toronto from 1892 to 1932, was professor of physics from 190...

Lalande, Joseph Jérôme Lefrançais de

(Encyclopedia)Lalande, Joseph Jérôme Lefrançais de läläNdˈ [key], 1732–1807, French astronomer. Under the direction of the French Academy of Science, he went to Berlin in 1751 to make observations on the p...

sidereal period

(Encyclopedia)sidereal period, in astronomy, length of time a body takes to complete an orbit relative to the fixed stars. See sidereal time. ...

linden, in botany

(Encyclopedia)CE5 Linden, Tilia americana linden, common name for the Tiliaceae, a family of chiefly woody shrubs and trees. Most genera are tropical, but the genus Tilia, commonly called linden, or lime tree, ...

lens, in optics

(Encyclopedia)CE5 Lenses lens, device for forming an image of an object by the refraction of light. In its simplest form it is a disk of transparent substance, commonly glass, with its two surfaces curved or wi...

larkspur, in botany

(Encyclopedia)larkspur, any north temperate, Old World annual of the genus Consolida of the buttercup family. Consolida species were formerly classified in the genus Delphinium, which includes similar annual, bienn...

larva, in zoology

(Encyclopedia)larva, independent, immature animal that undergoes a profound change, or metamorphosis, to assume the typical adult form. Larvae occur in almost all of the animal phyla; because most are tiny or micro...

labor, in physiology

(Encyclopedia)labor: see birth.

labor, in economics

(Encyclopedia)labor, term used both for the effort of performing a task and for the workers engaged in the activity. In ancient times much of the work was done by slaves (see slavery). In the feudal period agricult...

laurel, in botany

(Encyclopedia)CE5 Sassafras, Sassafras albidum, a member of the laurel family laurel, common name for the Lauraceae, a family of forest trees and shrubs found mainly in tropical SE Asia but also abundant in tro...