A ER 



^TH 



given by Bergman n to carbonic acid, from 

 an idea that it entered into the compo- 

 sition of atmospheric air. 



A'ERIFORM {aer, air, forma, like- 

 ness). Air-like ; a term applied to gase- 

 ous fluids, from their resemblance to 

 common air. See Gas. 



A'ERO-DYNA'MICS (<i;/p, iepof, air, 

 ivva/jiii, power). The science which treats 

 of the rhotion of the air, and of the me- 

 chanical effects of the air in motion. 



A'EROGRAPHY (ci^/p, ^epo^, the air, 

 •ypa^o), to describe). A description of the 

 nature, properties, and limits of the at- 

 mosphere. 



A'EROLITE (oJJ/p, iepof, air, XiOo?, a 

 stone). A meteoric stone, or mineral 

 mass, which falls through the air, accom- 

 panied with the disengagement of light, 

 and a noise like thunder. These masses 

 invariably contain iron, cobalt, or nickel, 

 or a combination of these three metals> 

 in union with various earthly substances. 

 They have a specific gravity of from 3.3 

 to 4.3, and are more or less magnetic. 



AERO'METER (.iijp, a'epo?, air, /xe- 

 rpov, a measure). An instrument con- 

 structed by Dr. M. Hall, for ascertaining 

 the changes in the temperature of the 

 atmosphere; in the barometrical pres- 

 sure ; in the external and internal heights 

 of the fluid in the pneumatic trough ; 

 and, when this trough contains water, for 

 the elevation and precipitation of aqueous 

 vapour. 



A'ERONAU'TICS {atjp, depo^, air, 

 vavTiKoi, belonging tc ships). The art of 

 navigating the air, by means of a balloon. 



A'EROPHYTES (d^P, afpor, the air, 

 (pvTov, a plant). Plants which live ex- 

 clusively in air, as distinguished from 

 hydrophytps, which live in water. 



AERO'SCOPY {ut]p, depo^, air, a-Koneu), 

 to observe). The observation of the air. 



A'EROSTAT {iii^p, Ciepov, the air, 

 o-Tcicrtf, a standing). An air-balloon, or 

 hollow sphere^ composed of flexible and 

 air-tight materials, and filled with some 

 elastic fluid whose specific gravity is 

 much less than that of atmospheric air. 

 See Montgolfier. 



A'EROSTA'TICS {dhp, depo?, air, 

 <ndatf, a standing). The science which 

 treats of the equilibrium of air and other 

 elastic fluids. 

 > A'EROSTA'TION {atjp, aepo^, the air, 

 o-Tfio-t?, a standing). A science depend- 

 ing on the statical operations of our 

 atmosphere, and exhibited in raising 

 heavy bodies into the air, by the buoyancy 

 of gases of small specific gravity. In 

 10 



other words, it is the science which 

 teaches the equilibrium of bodies sup- 

 ported in air. 



^RU'GO {ces, copper). Verdigris ; 

 an impure subacetate of copper, formed 

 by placing piates of the metal in contact 

 with the vapours of vinegar. 



^'SCULA'CEiE. The Horse-Chestnut 

 tribe of Dicotyledonous plants, named 

 from the genus ^Esculus. Trees or 

 shrubs, with leaves opposite; flowers un- 

 symmetrical; stamens 7 or 8, unequal, 

 hypogynous ; ovary 3-celled ; fruits 1-2 

 or 3-valved ; seeds large, with a broad 

 hilum, exalbuminous. 



^STHE'TICS (aiV^no-'f, perception). 

 That science which refers the first prin- 

 ciples in the arts to sensation and senti- 

 ment, as distinguished from mere in- 

 struction and utility. •' Art," says Meu- 

 zel, " is not the result of understanding 

 alone ; the inspiration of the artist has 

 been, and ever must be, the source of 

 that which gives aesthetic value to his 

 productions." 



^STIVA'TION {cEstivus, belonging to 

 summer). Prcefloration. A botanical 

 term, denoting the manner in which the 

 floral envelopes are arranged with respect 

 to each other, before their expansion 

 Thus, in the Umbelliferae, the aestivation 

 is valvate ; in Rosa, it is qnincuncinl ; in 

 papilionaceous flowers, it is vexillary, 

 &c. See Vernation. 



iE'STUARY [cBstuarium, a firth). An 

 arm of the sea in which the tide ebbs and 

 flows. A channel of a river contiguous 

 to the sea, in which the influence of the 

 tides is perceptible, without distinct cur- 

 rent. 



^'THEO'GAMOUS {dhOm, unusual, 

 '■idixot, marriage). A term applied to 

 what are otherwise called cryptogamous 

 plants, from the notion that their mode 

 of reproduction is of an unusual rather 

 than of a hidden nature. The term would 

 be more correctly written a'etheogamous. 



iETHER (a\dh9, ether). A highly 

 limpid, volatile, and inflammable fluid, 

 produced by the action of acids on alco- 

 hol. 



^'THIOPS (at^o), to burn, w»^, the 

 eye or countenance). A designation of 

 various chemical compounds, derived 

 from their black appearance, resembling 

 that of the ^thiop. Thus we have 

 cBthiops mineral, or the black sulphuret 

 of mercurj' ; csthiops per se, or the grey 

 oxide of mercury ; cethiops martial, an 

 old name of the deutoxide of iron ; and 

 vegetable athiops, a species of charcoal, 



