will be found treated at considerable length in the articles Gravitation; Electricity; and Magnetism.
AT'TRIBUTE (Lat. attributum, from ad, to + tribuere, to ascribe). (1) In painting and sculpture, a symbol associated with a figure to describe and emphasize its meaning in a religious, mythological, or allegorical subject. No period of art has been without attributes, but they have been most important at times when art has been less able to give character to the figures themselves, so that they can be recognized without the help of the accompanying attributes. The brush is the attribute of the painter; the stylus, of the scribe; the crown, of royalty; wings, of genii and angels. These are class attributes. In mythology the cow is the attribute of Hathor (Egypt); the tiger, of Ishtar (Assyria); the club, of Heracles; the trident, of Poseidon or Neptune (Græco-Roman). In Christian art, the gridiron is the attribute of Saint Lawrence; the lamb, of Saint Agnes; the keys, of Saint Peter. Attributes differ from emblems (q.v.) and symbols in having no value apart from their figures. (2) In logic, a mark or quality considered as giving character to an object of thought. (See Logic.) It is a term much used in Christian theology to denote some characteristic of the Divine nature, such as omniscience.
ATTRI'TION. See Contrition.
ATTU, iit'too, or ATTOO.
One of the extreme western islands of the Aleutian Group, nearer the coast of Asia than that of America, latitude 52° 58' N., longitude 172° 66' E. (Map: Arctic Regions, A 4). Upon it is a small village, with less than 100 native families.
AT'TUCKS, Crispus. The first man killed in the 'Boston Massacre' (q.v.), March 5, 1770. He was a half-breed Indian, or a mulatto, of Framingham, Mass., born about 1720. By some he is said to have been a quiet on-looker; by others, a ringleader in the disturbance. A monument to him has been erected in Boston. Consult the American Historical Record for 1872.
AT'WATER, Wilbur Olin (1844—). An
American chemist. He was born at Johnsburg,
N. Y., and graduated at Wesleyan University,
Middletown, Conn., in 1865, received his doctor's
degree from Yale University in 1869, and after-
wards studied physiological and agricultural
chemistry at the universities of Leipzig and
Berlin. He was professor of chemistry at East
Tennessee University, at Maine State College,
and at Wesleyan University. He was first di-
rector of the Connecticut Agricultural Experi-
ment Station from 1875 to 1877, and of the Office
of Experiment Stations, United States Depart-
ment of Agriculture, from 1888 to 1891. Since
1887 he has been director of the Storrs (Conn.)
Experiment Station, and since 1894 has had
charge of nutrition investigations of the United
States Department of Agriculture. In conjunc-
tion with Rosa, he invented the well-known
respiration calorimeter for experiments on the
metabolic changes going on in the human body.
Dr. Atwater is the author of numerous articles
on physiological and agricultural chemistry, pub-
lished with Government and experiment station
reports, and in various scientific and popular
journals.
AT'WILL, Edward Robert (1840—). An
American clergyman. He was born at Red
Hook, N. Y.; graduated at Columbia College in
1862, and at the General Theological Seminary,
in New York City, in 1864. He entered the
ministry of the Protestant Episcopal Church,
and after service in New York, Vermont, and
Ohio, became Bishop of West Missouri in 1890.
AT'WOOD, Charles B. (1849-95). An American architect, noted principally as the designer of W. H. Vanderbilt's house on Fifth Avenue, New York, and as designer-in-chief of the World's Fair buildings in Chicago, where the Art Building and Peristyle Court were his work.
ATWOOD, George (1746-1807). An English mathematician and physicist. He was born in London, and graduated at Trinity College, Cambridge, with high honors in 1769. Subsequently he was appointed fellow and tutor. He received the degree of M.A. in 1772, and was elected a member of the Royal Society in 1776. Through the influence of William Pitt, he was appointed to a position in the customs service, where he performed a number of important mathematical calculations connected with the revenue. The apparatus known as Atwood's Machine (q.v.), which was designed to show the acceleration of gravity, was described in his Treatise on the Rectilinear Motion and Rotation of Bodies, with a Description of Original Experiments Relative to the Subject (1784). He also wrote A Description of the Experiments Intended to Illustrate a Course of Lectures on the Principles of Natural Philosophy (1776), and An Analysis of a Course of Lectures on the Principles of Natural Philosophy (1784), as well as a number of papers on mathematical subjects, published for the most part in the Philosophical Transactions. For one of these he received the Copley Medal in 1796.
ATWOOD, Isaac Morgan (1838—). A Universalist clergyman, born at Pembroke, N. Y. He became a Universalist minister in 1859, and was the president of the Canton (N. Y.) Theological School, and professor of theology from 1879 till 1899. Afterwards he became general superintendent of the denomination in United States and Canada. His publications embrace: A Glance at the Religious Progress of the United States (1874); Walks About Zion (1881); Revelation (1888); Balance Sheet of Biblical Criticism (1895). He edited The Latest Word of Universalism (1878).
ATWOOD'S MACHINE, ma-shen'.
An instrument for illustrating the relations of time, space, and velocity in the motion of a body falling under the action of gravity, invented by George Atwood (q.v.). It is known that a body falling freely passes through 16 feet in the first second, 64 feet in the first two seconds, 144 feet in the first three seconds, and so on. Now, as these spaces are so large, it would require a machine of impracticable size to illustrate the relations just mentioned. The object of Atwood's machine is to reduce the scale on which gravity acts without in any way altering its essential features as an accelerating force. The machine consists essentially of a pulley, P (see the cut), moving on its axis with very little friction, with a fine silk cord passing over it, sustaining two equal cylindrical weights, p and g, at its extremities. The pulley rests on a
