NOD 



NON 



discovered by Nobili, If a feeble current 

 be applied to polished plates of platinum, 

 steel, and silver, by using them as elec- 

 trodes, and immersing them in an elec- 

 trolytic fluid, certain figures will be visi- 

 ble, generally in the form of concentric 

 circles whose centre is exactly opposite to 

 the point of the wire, very much resem- 

 bling Newton's Prismatic Rings, and so 

 firmlyfixed, that they cannot be removed 

 even by washing the metal with nitric acid. 



NOCTILIONl'N^. A family of in- 

 sectivorous Cheiroptera, which are desti- 

 tute of nasal appendages, and are almost 

 exclusively confined to tropical coun- 

 tries. 



NOCTU'RNA {nocturnus, nightly). A 

 designation of the true moths, a tribe of 

 Lepidopterous insects, the greater part 

 of which fly by night. 



NODAL LINES. A term employed 

 in speaking of the undulations of solid 

 bodies. Thus, in the movements of 

 elastic planes, complete rows of points, 

 called nodal lines, will be formed which 

 do not participate in the movements of 

 the planes, but are in a state of rest. 

 These nodal lines are produced by the 

 continuous succession of nodal points, in 

 the strings of which the plane is supposed 

 to consist. They run in various direc- 

 tions across the plane, dividing it into 

 numerous vibrating portions, the con- 

 tiguous portions invariably moving in 

 contrary directions. The nodal lines 

 form peculiar figures, called, after their 

 discoverer, Chladni's Sonorous Figures. 



NODAL POINTS. When a tense 

 cord is thrown into vibration, it assumes 

 throughout its entire length the form of 

 elevations and depressions impinging on 

 oae another, the elevation passing into 

 the form of a depression, and vice versa. 

 The point which bounds an elevation and 

 a depression, continuing at rest during 

 the vibration, is called a nodal point. 



NODE {nodus, a knot). In astronomy, 

 the nodes are the points where the orbit 

 of a planet cuts the plane of the ecliptic. 

 The node whence the planet rises to- 

 wards the north above the plane of the 

 ecliptic is the ascending node, that whence 

 it descends towards the south is the de- 

 scending node; the line joining the two 

 is called the line of the nodes. Generally, 

 the point in which one orbit cuts another 

 is called the node of the first upon the 

 second. 



NODE (in Botany). This term signi- 

 fies the thickened part of a stem or 

 branch from which a leaf is developed. 

 234 



The space between two nodes is termed 

 an iniernode. 



NO'DULE (dim. of nodus, a node). 

 A little node ; a small woody body found 

 in the bark of the beech and some other 

 trees, and formed of concentric layers 

 of wood arranged around a central nu- 

 cleus. Dutrochet terms it an embryo- 

 bud. 



NODULE (in Geology). A rounded 

 irregular-shaped lump or mass, varying 

 in size, and embedded in a stratified or a 

 massive rock. 



NOMENCLATURE. A general de- 

 signation of the terms employed in any 

 science or art. 



NOMINAL DEFINITION. In logic, 

 a definition which explains only the 

 meaning of the term defined, and nothing 

 more of the nature of the thing signified 

 by that term than is implied by the term 

 itself to every one who understands the 

 meaning of it. See Real Definition. 



NOMINALISTS and REALISTS. 

 Two scholastic sects of the 11th century, 

 the former of which afltirmed, according 

 to the Platonic doctrine, that names or 

 general terms have, apart from the mere 

 conception of them by the understand- 

 ing, an actual and eternal existence, and 

 are the models of all created beings; 

 while the latter maintained, according to - 

 the doctrine of Aristotle, that these 

 names were eternally united to matter, 

 and have no existence as unconnected 

 with it. See Idea. 



NO'MINATIVE CASE (nomino, to 

 name). The naming case; the case 

 which precedes the verb, and designates 

 its subject absolutely, without relation 

 to any other subject. A noun in the 

 nominative case [casus rectus) was con- 

 sidered by ancient grammarians as a 

 line perpendicular ; and in the other 

 cases {casus obliqui) as gradually decli- 

 nijzg or falling from the perpendicular. 

 To decline a noun, is, therefore, to make 

 it pass through these cases or fallings, 

 and the representation of them is called 

 a declension. 



NON CAUSA PRO CAUSA. A logi- 

 cal fallacy in which the premiss (whether 

 the expressed or the suppressed one) is 

 either proved false, or has no suflicient 

 claim to be received as true. 



NON-CONDUCTORS. Substances 

 which carry off free electricity slowly 

 when touched by an electrified body ; or, 

 if their condition of electrical indiffer- 

 ence is disturbed at any one point, they 

 become electrical at that point only ; and 



