Accelera′tion is the rate of change of the velocity of a body under the action of a force. A body falling from a height is one of the most common instances of acceleration.—Acceleration of the Moon, the increase of the moon's mean angular velocity about the earth, the moon now moving rather faster than in ancient times. This phenomenon has not been fully explained, but it is known to be partly owing to the slow process of diminution which the eccentricity of the earth's orbit is undergoing, and from which there results a slight diminution of the sun's influence on the moon's motions.—Diurnal acceleration of the fixed stars, the apparent greater diurnal motion
of the stars than of the sun, arising from the fact that the sun's apparent yearly motion takes place in a direction contrary to that of his apparent daily motion. The stars thus seem each day to anticipate the sun by nearly 3 minutes 56 seconds of mean time.
Ac′cent, a term used in several senses. In English it commonly denotes superior stress or force of voice upon certain syllables of words, which distinguishes them from the other syllables. Many English words, as as′pi-ra″tion, have two accents, a secondary and primary, the latter being the fuller or stronger. Some words, as in-com′pre-hen′si-bil″i-ty, have two secondary or subordinate accents. When the full accent falls on a vowel, that vowel has its long sound, as in vo′cal; but when it falls on a consonant, the preceding vowel is short, as in hab′it. This kind of accent alone regulates English verse, as contrasted with Latin or Greek verse, in which the metre depended on quantity or length of syllables. In books on elocution three marks or accents are generally made use of, the first or acute (´) showing when the voice is to be raised, the second or grave (`), when it is to be depressed, and the third or circumflex (ˆ) when the vowel is to be uttered with an undulating sound. In some languages there is no such distinct accent as in English (or German), and this seems to be now the case with French.—In music, accent is the stress or emphasis laid upon certain notes of a bar. The first note of a bar has the strongest accent, but weaker accents are given to the first notes of subordinate parts of the bars, as to the third, fifth, and seventh in a bar of eight quavers.
Accen′tor (Accentor modulāris), or Hedge Accentor, a British bird of the warbler family. See Hedge Warbler.
Accep′tance, in law, the act by which a person binds himself to pay a bill of exchange drawn upon him. (See Bill.) No acceptance is valid unless made in writing on the bill, but an acceptance may be either absolute or conditional, that is, stipulating some alteration in the amount or date of payment, or some condition to be fulfilled previous to payment.
Ac′cessary, or Ac′cessory, in law, a person guilty of an offence by connivance or participation, either before or after the act committed, as by command, advice, concealment, &c. An accessary before the fact is one who procures or counsels another to commit a crime, and is not present at its commission; an accessary after the fact is one who, knowing a felony to have been committed, gives assistance of any kind to the felon so as to hinder him from being apprehended, tried, or suffering punishment. An accessary before the fact may be tried and punished in all respects as if he were the principal. In high treason, all who participate are regarded as principals.
Acciden′tals, notes introduced in the course of a piece of music in a different key from that in which the passage where they occur is principally written. They are represented by the sign of a sharp, flat, or natural immediately before the note which is to be raised or lowered.
Accipitres (ak-sip′i-trēz), the name given by Linnæus and Cuvier to the rapacious birds now usually called Raptores (q.v.).
Acclimatiza′tion, the process of accustoming plants or animals to live and propagate in a climate different from that to which they are indigenous, or the change which the constitution of an animal or plant undergoes under new climatic conditions, in the direction of adaptation to those conditions. The systematic study of acclimatization has only been entered upon in very recent times, and the little progress that has been made in it has been more in the direction of formulating anticipative, if not arbitrary hypotheses, than of actual discovery and acquisition of facts. The best-known society founded, for the purpose of naturalizing animals and plants, is the Société d'Acclimatation in Paris. It opened the Jardin d'Acclimatation in 1860. See Tropical Hygiene. The term is sometimes applied to the case of animals or plants taking readily to a new country with a climate and other circumstances similar to what they have left, such as European animals and plants in America and New Zealand: but this is more properly naturalization than acclimatization.—In agriculture the word is used with reference to stock, principally sheep, 'acclimatized' to a particular area, a special allowance being made by the landlord on transference of the farm and stock in respect of the acclimatization of the sheep. The value assigned to the advantages resulting from acclimatization of stocks varies considerably. In Argyllshire, for instance, Dumbartonshire, and the western portion of Perthshire the rates are high, while in the south of Scotland and the north of England they are much lower.
Accolade (ak-o-lād′; Fr., from Lat. ad, to, collum, the neck), the ceremony used in conferring knighthood, anciently consisting either in the embrace given by the person who conferred the honour of knighthood or in a light blow on the neck or the cheek, latterly consisting in the ceremony of striking the candidate with a naked sword.