Part 743

<p><b>3.</b> <def>Caused, or operated on, by the atmosphere; <as>as, an <ex>atmospheric</ex> effect; an <ex>atmospheric</ex> engine.</as></def>

<p><b>4.</b> <def>Dependent on the atmosphere.</def> <mark>[R.]</mark>

<blockquote>In am so <b>atmospherical</b> a creature. <i>Pope.</i></blockquote>

<cs><col>Atmospheric engine</col>, <cd>a steam engine whose piston descends by the pressure of the atmosphere, when the steam which raised it is condensed within the cylinder.</cd> <i>Tomlinson</i>. -- <col>Atmospheric line</col> <fld>(Steam Engin.)</fld>, <cd>the equilibrium line of an indicator card. Steam is expanded "down to the atmosphere" when its pressure is equal to that of the atmosphere. (See <er>Indicator card</er>.)</cd> -- <col>Atmospheric pressure</col>, <cd>the pressure exerted by the atmosphere, not merely downwards, but in every direction. In amounts to about 14.7 Ibs. on each square inch.</cd> -- <col>Atmospheric railway</col>, <cd>one in which pneumatic power, obtained from compressed air or the creation of a vacuum, is the propelling force.</cd> -- <col>Atmospheric tides</col>. <cd>See under <er>Tide</er>.</cd></cs>

<h1>Atmospherically</h1> <Xpage=96>

<hw>At`mos*pher"ic*al*ly</hw> <tt>(#)</tt>, <tt>adv.</tt> <def>In relation to the atmosphere.</def>

<h1>Atmospherology</h1> <Xpage=96>

<hw>At`mos*phe*rol"o*gy</hw> <tt>(#)</tt>, <tt>n.</tt> <ety>[<ets>Atmosphere</ets> + <ets>-logy</ets>.]</ety> <def>The science or a treatise on the atmosphere.</def>

<h1>Atokous</h1> <Xpage=96>

<hw>At"o*kous</hw> <tt>(#)</tt>, <tt>a.</tt> <ety>[Gr. <?/ barren; <?/ priv. + <?/ offspring.]</ety> <fld>(Zo\'94l.)</fld> <def>Producing only asexual individuals, as the eggs of certain annelids.</def>

<h1>Atoll</h1> <Xpage=96>

<hw>A*toll"</hw> <tt>(#)</tt>, <tt>n.</tt> <ety>[The native name in the Indian Ocean.]</ety> <def>A coral island or islands, consisting of a belt of coral reef, partly submerged, surrounding a central lagoon or depression; a lagoon island.</def>

<h1>Atom</h1> <Xpage=96>

<hw>At"om</hw> <tt>(#)</tt>, <tt>n.</tt> <ety>[L. <ets>atomus</ets>, Gr. <?/, uncut, indivisible; <?/ priv. + <?/, verbal adj. of <?/ to cut: cf. F. <ets>atome</ets>. See <er>Tome</er>.]</ety> <p><b>1.</b> <fld>(Physics)</fld> <sd>(a)</sd> <def>An ultimate indivisible particle of matter.</def> <sd>(b)</sd> <def>An ultimate particle of matter not necessarily indivisible; a molecule.</def> <sd>(c)</sd> <def>A constituent particle of matter, or a molecule supposed to be made up of subordinate particles.</def>

<note>&hand; These three definitions correspond to different views of the nature of the ultimate particles of matter. In the case of the last two, the particles are more correctly called <i>molecules</i>.</note>

<i>Dana.</i>

<p><b>2.</b> <fld>(Chem.)</fld> <def>The smallest particle of matter that can enter into combination; one of the elementary constituents of a molecule.</def>

<p><b>3.</b> <def>Anything extremely small; a particle; a whit.</def>

<blockquote>There was not an <b>atom</b> of water. <i>Sir J. Ross.</i></blockquote>

<h1>Atom</h1> <Xpage=96>

<hw>At"om</hw>, <tt>v. t.</tt> <def>To reduce to atoms.</def> <mark>[Obs.]</mark>

<i>Feltham.</i>

<h1>Atomic, Atomical</h1> <Xpage=96>

<hw><hw>A*tom"ic</hw> <tt>(#)</tt>, <hw>A*tom"ic*al</hw> <tt>(#)</tt>,<hw> <tt>a.</tt> <ety>[Cf. F. <ets>atomique</ets>.]</ety> <p><b>1.</b> <def>Of or pertaining to atoms.</def>

<p><b>2.</b> <def>Extremely minute; tiny.</def>

<cs><col>Atomic philosophy</col>, <cd>or <i>Doctrine of atoms<i>, a system which assuming that atoms are endued with gravity and motion accounted thus for the origin and formation of all things. This philosophy was first broached by Leucippus, was developed by Democritus, and afterward improved by Epicurus, and hence is sometimes denominated the <i>Epicurean<i> philosophy.</cd> -- <col>Atomic theory</col>, <cd>or the <i>Doctrine of definite proportions<i> <fld>(Chem.)</fld>, teaches that chemical combinations take place between the supposed ultimate particles or <i>atoms<i> of bodies, in some simple ratio, as of one to one, two to three, or some other, always expressible in whole numbers.</cd> -- <col>Atomic weight</col> <fld>(Chem.)</fld>, <cd>the weight of the atom of an element as compared with the weight of the atom of hydrogen, taken as a standard.</cd></cs>

<h1>Atomically</h1> <Xpage=96>

<hw>A*tom"ic*al*ly</hw>, <tt>adv.</tt> <def>In an atomic manner; in accordance with the atomic philosophy.</def>