ABERDEVINE ABERRATION favorite rendezvous of sportsmen. The Bullers of Buchan, near Peterhead, are also an at- tractive object to the tourist. The chief rivers are the Dee and the Don. The climate, ex- cept in the mountain districts, is mild, and wheat prospers. Cattle, sheep, pigs, eggs, and butter are transported by steam from Aber- deen to London, to the value of about 1,000,- 000 annually. Granite is the most important mineral production. Besides the queen's es- tate of Balmoral, Aboyne castle, belonging to the earl of Aboyne, Haddo houSe, seat of the earl of Aberdeen, Huntly lodge, of the duke of Richmond, and Forbes castle are noteworthy. ABERDEVINE (carduelis spinus), also called the siskin, a small European song bird, which breeds in the north of Europe, and visits Eng- land, France, and Germany during the winter season only. It somewhat resembles the green variety of the canary bird, with which it is so far connected that it will interbreed with it in confinement, when the produce is what are known by bird fanciers as mules. Its length is about 4f inches, its tail short and forked. Its upper parts are variegated with olive brown, yellow, and pale green, the feath- ers being edged with yellow ; its bill and legs are light horn brown. Its note is soft and pleasant. It builds in the topmost branches of pine trees, and lays four or five bluish white eggs, speckled with purplish red. Its Latin name carduelis expresses its fondness for the seeds of the thistle. ABERNETHY, John, an English surgeon, born either in Scotland or Ireland in 1764, died at Enfield, April 18, 1831. He was a pupil of Sir Charles Blick, surgeon to St. Bar- tholomew's hospital, London, and afterward of the celebrated John Hunter. Early in his career, in a work entitled " The Constitutional Origin and Treatment of Local Diseases," he established the fundamental principles upon which surgical operations have since been con- ducted. His bold and successful operations of tying the carotid and external iliac arteries established his reputation, and almost revolu- tionized surgery. He acquired great distinc- tion as an anatomist and physiologist, suc- ceeded Sir Charles Blick at St. Bartholomew's, was appointed surgeon to Christ's hospital in 1813, and in 1814 professor of anatomy and sur- gery to the royal college of surgeons. His works became text books in nearly all the medical colleges in Europe and America. He contributed the anatomical and physiological articles to Dr. Rees's " Cyclopaedia " from A to C, and published numerous tracts, treatises, and surgical and physiological essays. One of the most popular and well known of his works was his "Surgical Observations," the pe- rusal of which he almost invariably recom- mended to his patients. His last production (issued a few months prior to his death) was a collected and revised edition of his " Lectures on the Theory and Practice of Surgery." His writings are remarkable for clearness, concise- ness, and simplicity. His simple and impres- sive style of lecturing never failed to enchain his audience, despite his dogmatism and con- tempt of others' opinions. His private charac- ter was admirable, but in public his manners were uncouth, churlish, and capricious. Many anecdotes of his eccentricities are current. ABERRATION. I. Aberration of Light, the al- teration of apparent position in a heavenly body, due to the fact that the observer is car- ried along by the earth's motion, the velocity of which is a measurable quantity in relation to the velocity of light. The aberration of light is therefore due to the combined effect of the transmission of light and of the earth's motion. The solution of all problems to which it gives rise is due to the astronomers of the last century ; their calculations are in perfect accord with the minutest practical observa- tions, made with the most elaborate and largest astronomical instruments constructed in some observatories chiefly for the purpose of measur- ing this amount of aberration. If, at a time when rain drops were falling in a perfect calm per- pendicular to the earth's surface, we were standing on a platform car on a railroad track, and rapidly moving forward or backward, the drops would strike us under an angle deviating from the perpendicular in proportion to the swiftness of our motion. The direction of this deviation would in either case be toward the side we are moving to, and this is exactly the case with the light coming to us from the heavenly bodies. This is evident when we compare the direction of the rain drops with that of the light, and that of the car with the motion of the earth in its yearly orbit. If now the direc- tion in which light reaches us be changed, the apparent position of the body from which the light proceeds must be changed also. Let A B T T'
A * B C Aberration of Light. represent a small portion of the earth's orbit, and S M the ray of light from a fixed star S ; the motion of the earth from B toward A will cause the light to come in the direction S' A, and the star will appear to stand in S'. If C D represents a small portion of the earth's orbit half a year later, thus moving in an opposite direction, the star T will for the same rea-
