9. (Math.) Belonging to, to be taken in, or referred to, some system,
in which the base is 1; -- said or certain functions or numbers; as,
natural numbers, those commencing at 1; natural sines, cosines, etc.,
those taken in arcs whose radii are 1.
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10. (Mus.) (a) Produced by natural organs, as those of the human
throat, in distinction from instrumental music. (b) Of or pertaining to
a key which has neither a flat nor a sharp for its signature, as the
key of C major. (c) Applied to an air or modulation of harmony which
moves by easy and smooth transitions, digressing but little from the
original key. Moore (Encyc. of Music).
Natural day, the space of twenty-four hours. Chaucer.
-- Natural fats, Natural gas, etc. See under Fat, Gas. etc. -- Natural
Harmony (Mus.), the harmony of the triad or common chord. -- Natural
history, in its broadest sense, a history or description of nature as a
whole, incuding the sciences of botany, zoölogy, geology, mineralogy,
paleontology, chemistry, and physics. In recent usage the term is often
restricted to the sciences of botany and zoölogy collectively, and
sometimes to the science of zoology alone. -- Natural law, that
instinctive sense of justice and of right and wrong, which is native in
mankind, as distinguished from specifically revealed divine law, and
formulated human law. -- Natural modulation (Mus.), transition from one
key to its relative keys. -- Natural order. (Nat. Hist.) See under
order. -- Natural person. (Law) See under person, n. -- Natural
philosophy, originally, the study of nature in general; in modern
usage, that branch of physical science, commonly called physics, which
treats of the phenomena and laws of matter and considers those effects
only which are unaccompanied by any change of a chemical nature; --
contrasted with mental and moral philosophy. -- Natural scale (Mus.), a
scale which is written without flats or sharps. Model would be a
preferable term, as less likely to mislead, the so-called artificial
scales (scales represented by the use of flats and sharps) being
equally natural with the so-called natural scale -- Natural science,
natural history, in its broadest sense; -- used especially in
contradistinction to mental or moral science. -- Natural selection
(Biol.), a supposed operation of natural laws analogous, in its
operation and results, to designed selection in breeding plants and
animals, and resulting in the survival of the fittest. The theory of
natural selection supposes that this has been brought about mainly by
gradual changes of environment which have led to corresponding changes
of structure, and that those forms which have become so modified as to
be best adapted to the changed environment have tended to survive and
leave similarly adapted descendants, while those less perfectly adapted
have tended to die out though lack of fitness for the environment, thus
resulting in the survival of the fittest. See Darwinism. -- Natural
system (Bot. & Zoöl.), a classification based upon real affinities, as
shown in the structure of all parts of the organisms, and by their
embryology.
It should be borne in mind that the natural system of botany is
natural only in the constitution of its genera, tribes, orders,
etc., and in its grand divisions.
Gray.
-- Natural theology, or Natural religion, that part of theological
science which treats of those evidences of the existence and attributes
of the Supreme Being which are exhibited in nature; -- distinguished
from revealed religion. See Quotation under Natural, a., 3. -- Natural
vowel, the vowel sound heard in urn, furl, sir, her, etc.; -- so called
as being uttered in the easiest open position of the mouth organs. See
Neutral vowel, under Neutral and Guide to Pronunciation, § 17.
Syn. -- See Native.
Nat"u*ral (?; 135), n. 1. A native; an aboriginal. [Obs.] Sir W.
Raleigh.