PRISMATIC 



274 



PROPIONE 



usually parallel; usually means a solid with 

 three rectangular faces and two triangular 

 ends. Nicol's P., v. Nicol's Prism. 



Prismatic, (priz-mat'ik). [Prism, q.v.} Re- 

 lating to a prism. P. colours: the seven 

 colours of the spectrum, v. Spectrum. /'. 

 s?/ste)H=Orthorhornbic, q.v. 



Prismatocarpus, (priz-mat-6-kar'pus). A plant 

 belonging to Campanulaceae. P. speculnm= 

 Veuus's looking-glass. 



Pristis, (pris'tis). [Gk. pristes, sa\ver.]= Saw- 

 fish: having a long serrated snout; belongs 

 to Raiidse. 



Privet, (priv'et).=Ligustrum, q.v. P. moth 

 =Sphinx ligustri: larvae feed on privet. 



Problem, (prob'lem). [Problema, the Latin 

 word.] In geometry, something that has 

 to be done according to prescribed condi- 

 tions, and when done demonstrated to be 

 so; generally, any task which is impliedly 

 difficult. 



Proboscidea, (pro-bos-sid'e-a). [Proboscis, q.v. ; 

 Gk. eidos, form.] Elephants; animals be- 

 longing to Mammalia, known by their tusk- 

 like incisor teeth, and by the nose being 

 prolonged into a trunk. 



Proboscis, (pro-bos'sis). [The Latin word.] 

 l.=Snout; used also for the trunk of an ele- 

 phant. 2. =Manubrium: in Discophora. P. 

 moner/:=Nasali8=Sinna nasalis. 



Procellaridse, (pros-el-la'ri-de). [Procellam, 

 the typical genus.] Petrels: a family of birds 

 belonging to Natatores. 



Procellarum, (pros-el-la'rum). [L. procella, 

 storm. ]=Oceanus procellarurn : the largest of 

 the plains (formerly called seas) on the surface 

 of the Moon; about 90,000 sq. m. in extent. 



Processes, (pro'ses-sez). v. Floccular, Jngras- 

 sias, and Mammillary. 



Processionary moth = Cnethocampa proces- 

 sions: march out in armies. 



Prochilus, (pro-ki'lus). [Gk. procheilos, thick- 

 lipped. P. ia&i<ws=81oth-bear. 



Procoelia, (pro-se'li-a). [Gk. protos, first ;koilos, 

 hollow.] A sub-division of Oocodilia, q.v.; 

 named from the vertebrae being hollow in 

 front. 



Procoelous, (pro'se-lus). [Gk. pro, front; Icoilos, 

 hollow.] Vertebrae which are hollow in front. 



Proculus, (prok'u-lus). [Classical.] A moun- 

 tain-peak in the Moon. 



Procyon, (pro'si-on). [Gk. pro, before; kyon, 

 dog.]=Precursor Dog: a binary star, the chief 

 star of Canis Minor, having a blue colour. 



Productus, (pro-duk'tus). [L. productus, drawn 

 out.] A bra- 

 c h i o p o d , 

 found fossil 

 in Permian 

 and Carboni- 

 ferous rocks; 

 named from 

 one valve of 

 the shell be- Productus Horridus. 



ing longer than the other. 



Product, (pro'dukt). [L. productus, produced.] 

 1. In chemistry, the result of any synthetic 

 operation. 2. In arithmetic, the resxilt of 

 multiplication. 



Proglottis, (pro-glot'tis). [Gk. pro-glottis, 

 point of tongue.] Zooids propagated from 

 a scolex by gemmation, which in turn pro- 

 duce ova. 



Projection, (pro -jek' shun). [L. projectus, 

 stretched out.] The delineation of solids on 

 a flat surface ; a branch of descriptive geo- 

 metry. Globular P.: used for map drawing, 

 in which the eye is at some distance (about 

 of the radius) from the surface of the 

 globe. Gnomonic P. ; in which the eye is 

 supposed to be at the centre of the solid body. 

 Isometric P.: in which the plane of projection 

 is equally inclined to three axes at right 

 angles to each other. Mercator'sP.: by which 

 maps are drawn with the parallels of lati- 

 tude and the meridians as straight lines; used 

 for navigation. Natural Ps.: stereographic, 

 orthographic, &c., as opposed to Mercator's 

 P., which is artificial. Orthographic P.: in 

 which the eye is supposed to be at an infinite 

 distance. Stereographic P.: in map drawing, 

 when the eye is supposed to be at the surface 

 of the globe, so that small portions of the 

 earth's surface can be drawn without distor- 

 tion. 



Prolification, (pro-lif-i-ka'shun). [L. proles, 

 offspring; facio, I make.]=Generation: espe- 

 cially used for the growth of secondary buds. 

 Med'ian P.: adventitious bud, springing from 

 centre of flower. Axillary P.; adventitious 

 bud, springing from centre of axil. Lateral 

 P.: adventitious bud, springing from centre 

 of inflorescence. 



Promerops, (pro'me- 

 rops). [Gk. pro, 

 before; merops, bee- 

 eater.] = Sun-bird : 

 brilliantly coloured 

 birds, with Jong 

 tails, belonging to 

 Upupidae. 



Prominences of sun, ^3; 

 v. Red P. 



Prominents.=Tooth-backs, q.v. 



Pronation, (pr5-na/shun). [L.pronus, leaning 

 towards.] Turning towards the earth; used 

 specially of the hand when the palm is turned 

 downwards. 



Prongbuck. A variety of the antelope. 



Proof plane = Carrier : a small piece of gilt 

 paper, with a non-conducting handle, used to 

 convey electricity from one body to another. 



Proof spirit. Alcohol strong enough to ignite 

 gunpowder when burning on it, and having 

 a specific gravity of '920. 



Prootic, (pro-ot'ik). [Gk. pro, front; oux, ear.] 

 An ossification in the auditory capsule. 



Propane, (pro'piin). = Hydride of propyle, 

 C3&8 : one of the marsh gas series. 



Prop eller, (pro-pel ' e r). 

 [L. propello, I urge for- 

 ward.] v. Screw-pro- 

 peller. 



Propionates, (pro'pi-o- 

 nats). [Propionic, q.v.] 

 Compounds of propi- 

 anic acid and bases. 



Propione, (pro 'pi -on). Propellers. 



