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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. ...

eider, in zoology

(Encyclopedia)eider: see duck.

diet, in nutrition

(Encyclopedia)diet, food and drink regularly consumed for nourishment. Nutritionists generally recommend eating a wide variety of foods; however, some groups of people survive on a very limited diet. The traditiona...

dike, in technology

(Encyclopedia)dike, in technology: see levee.

dimension, in mathematics

(Encyclopedia)dimension, in mathematics, number of parameters or coordinates required locally to describe points in a mathematical object (usually geometric in character). For example, the space we inhabit is three...

dimension, in physics

(Encyclopedia)dimension, in physics, an expression of the character of a derived quantity in relation to fundamental quantities, without regard for its numerical value. In any system of measurement, such as the met...

e, in mathematics

(Encyclopedia)e, in mathematics, irrational number occurring widely in mathematics and science, approximately equal to the value 2.71828; it is the base of natural, or Naperian, logarithms. The number e is defined ...

earth, in chemistry

(Encyclopedia)earth, in chemistry, metallic oxide not readily reducible by chemical means, e.g., alkaline earths, rare earths, and alumina. The name is also applied to certain absorbent clays, e.g., fuller's earth,...