NOD 



C 181 ] 



NOR 



layers. These nodules often contain, at 

 the centre, a kernel or nucleus, which is 

 sometimes moveable, and always differing 

 from the exterior in colour, density, and 

 fracture. The texture of the exterior is 

 compact and solid ; but the density gra- 

 dually diminishes to the centre, which has 

 an earthy texture. Specific gravity, about 

 2*57. Its constituents are oxide of iron 

 77'0, silex 6-0, oxide of manganese I'O, 

 alumine 0'5, water 13-5. These nodules 

 have also been called CEtites and Eagle- 

 stones, from an opinion that they were 

 found in eagles' nests, where, it was sup- 

 posed, they prevented the eggs from be- 

 coming rotten. 



Nodular iron ore is found disseminated 

 in beds of ferruginous clay in secondary 

 earths, and sometimes in alluvial deposites 

 of clay, loam, or sand. This ore is fre- 

 quently worked, and yields very good 

 iron. Nothing very satisfactory can be 

 said concerning the manner in which these 

 nodules have been formed. Cleaveland. 



NO'DULE. (from nodulus, a little knot, 

 Lat.) A rounded, irregular shaped, mi- 

 neral mass. 



NO'GROBS. A fossil resembling a belem- 

 nite. 



NOMENCLATURE, (nomenclatura, Lat. no- 

 menclature, Fr. collection des mots qui 

 sont propres auoc difftrentes parties d'une 

 science ou d'un art.) The names of 

 things in any art or science, or the whole 

 vocabulary of technical terms which are 

 appropriated to any particular branch of 

 art or science. 



The imposition of a name on any sub- 

 ject of contemplation is an epoch in its 

 history of great importance. It not only 

 enables us readily to refer to it in conver- 

 sation or writing, without circumlocution, 

 but, what is of more consequence, it gives 

 it a recognized existence in our own 

 minds, as a matter for separate and pe- 

 culiar consideration. How important a 

 good system of nomenclature is, may at 

 once be seen, by considering the immense 

 number of species presented by almost 

 every branch of science of any extent, 

 which absolutely require to be distin- 

 guished by names. Thus, the botanist 

 is conversant with from 80, 000 to 100,000 

 species of plants; the entomologist with, 

 perhaps, as many, of insects. And the 

 same as regards chemistry, astronomy, &c. 

 Nomenclature, then, is, in itself, an 

 important part of science, as it prevents 

 our being lost in a wilderness of parti- 

 culars, and involved in inextricable con- 

 fusion. Happily, in those great branches 

 of science, where the objects of classi- 

 fication are more numerous, and the ne- 

 cessity for a clear and convenient nomen- 

 clature most pressing, no very great diffi- 



culty in its establishment is felt. The 

 facility with which the chemist, the bo- 

 tanist, or the entomologist, refers by name 

 to any individual object in his science, 

 shows what may be effected in this way 

 when characters are themselves distinct. 



Nomenclature, in a systematic point of 

 view, is as much, perhaps more, a con- 

 sequence than a cause x>f extended know- 

 ledge. Any one may give an arbitrary 

 name to a thing, merely to be able to talk 

 of it ; but to give a name which shall at 

 once refer it to a place in a system, we 

 must know its properties ; and we must 

 have a system, large enough, and regular 

 enough, to receive it in a place which be- 

 longs to it and to no other. 



There is no science in which the evils 

 resulting from a rage for nomenclature have 

 been felt to such an extent as in mineralogy. 

 The nomenclature of most minerals is at 

 present so encumbered with synonyma, 

 that it has become extremely perplexing 

 to the student. This may be illustrated 

 by the example of Epidote. This mineral, 

 which is called epidote by Haiiy, is named 

 pistazit by Werner, thallite by Leme- 

 therie, akanticone by Dandrada, delphi- 

 nite by Saussure, glassy actinolite by 

 Werner, arendalit by Karsten, glassiger 

 strahlstein by Emm^rling, la rayonnante 

 vitreuse by Brochant, prismatoidischer 

 augit-spath by Mohs, &c. &c. 



In all subjects where comprehensive 

 heads of classification do not promi- 

 nently offer themselves, all nomenclature 

 must be a balance of difficulties, and a 

 good, short, unmeaning name, which has 

 once obtained a footing in usage, is pre- 

 ferable to almost any other. When the 

 composition is unknown, those names, 

 which are altogether unmeaning in re- 

 gard to any property of the thing, are, 

 perhaps, the least objectionable; at all 

 events, they cannot lead to error. 



Linnaeus was the first to introduce 

 systematic names into natural history. 

 By the introduction of these scientific, 

 fixed, and universally valid names, Lin- 

 naeus has undoubtedly acquired his great- 

 est merit in science, and if every thing 

 else which he has done should be for- 

 gotten, this, which is wholly his work, 

 will secure his name from forgetfulness. 

 Herschel. Cleaveland. Burmeister. 

 NO'RKA. The name given by Cronstadt to 

 an aggregate of quartz, mica, and garnet. 

 This aggregate is included by Kirwan in 

 the granatines. 



NO'RFOLK CRAG. An English tertiary for- 

 mation belonging to the older pliocene. 

 It is observed to rest on the chalk and on 

 the London clay. It consists of irregular 

 beds of ferruginous sand clay, mixed with 

 marine shells. According to an account 



