STR 



till objects on which it alights ; the latter 

 moistens every thing it touches. 



STREAM-MEASURER. An instru- 

 ment for measuring the velocity of a 

 stream of water at different depths. One 

 of the simplest is Pictofs tube ; it con- 

 sists of a tube bent nearly at a right 

 angle, expanding in a funnel shape; 

 this is placed into the direction of the 

 stream ; the upper part above the water 

 must be of glass. If the water be in a 

 state of rest, the level within and with- 

 out the tube will be equal ; but if it be 

 in motion, the impulse of the stream 

 will cause a column of the fluid to ascend 

 until the weight of this column become 

 a counterpoise to the force with which 

 the water is impelled. 



STREAM TIN. Tinstone, or native 

 oxide of tin, occurring in rounded par- 

 ticles and masses mixed with other allu- 

 vial matters. The finest grain tin is pro- 

 cured from this ore. 



STREPS I'PTER A {arpevros, twisted, 

 wxepov, a wing). A singular order of 

 Insects discovered by Mr. Kirby, in 

 which the anterior wings are reduced to 

 minute appendages twisted spirally. 



STRI'ATED {stria, a streak). Marked 

 with very slender lines, or striie, either 

 indented or elevated, at parallel and 

 nearly equal distances. When the lines 

 are deeper than striae, and indented, they 

 are called grooves ; when still deeper 

 and elevated, ridges. 



STRFGID^ {strix, the screech-owl). 

 The Owl tribe ; a family of the Raptores, 

 or Rapacious birds, including all the noc- 

 turnal birds of prey, and characterized 

 by the large proportion of the head to the 

 body, and by the size of the eyes, which 

 are surrounded by a fringe of feathers, 

 most remarkable in the barn owl and its 

 allies. 



STRI'GOSE (strigosus, scraggy). A 

 term applied to a surface covered with 

 sharp, appressed, rigid hairs ; a term 

 synonymous with hispid. 



STRO'BILE (o-Tpo/3i'\n, a plug of lint 

 twisted into an oval shape like a pine- 

 cone). Cone. An amentiform fruit, the 

 carpels of which are scale-like, spread 

 open, and bear naked seeds ; sometimes 

 the scales are thin, with little cohesion, 

 as in the hop ; but they are often woody, 

 and cohere into a single tuberculated 

 mass, as in the pine. See Galbulus. 



STROBOSCO'PIC PLATES {<Trp6fio9, 



a whirling round, crKonea}, to observe). 



An apparatus invented by Stampfer of 



Vienna, by which an impression is pro- 



318 



STR 



duced on the retina of an uninterrupted 

 line of light by the rapid motion of a 

 luminous object. On the same principle 

 is explained the action of the thauma- 

 trope, and of Newton's coloured wheels. 



STRO'MA. A fleshy body occurring 

 in fungaceous plants, to which flocci are 

 attached, as in isaria, &c. 



STRO'MBID^. Wing-shells ; a fa- 

 mily of carnivorous Gasteropods, named 

 from the typical genus strombus ; the 

 outer side or lip of the aperture is con- 

 siderably dilated. ♦ 



STRO'MBINiE. The true Wing- 

 shells ; a sub-family of the Stromhidce, 

 having the outer lip greatly dilated, with 

 a lobe at the base, and often on the sum- 

 mit also of the outer lip ; the spire being 

 always more or less elevated. 



STRO'NTIANITE. Carbonate of 

 strontia; a mineral of fibrous texture, 

 sometimes transparent and colourless, 

 but generally with a tinge of yellow or 

 green. 



STRO'NTIUM. The metallic base of 

 the alkaline earth strontia, named from 

 Strontian, a mining village in Argyle- 

 shire. The earth strontia is to barytes, 

 what soda is to potash. Sulphate of 

 strontia is known as celestine, and occurs 

 in regular crystals of the same form as 

 sulphate of barytes. 



STRO'PHIOL^. Carunculce. Irre- 

 gular protuberances sometimes occurring 

 about the umbilicus of seeds; in such 

 cases, the umbilicus is said to be stro- 

 phiolate or carunculate. 



STRUCTURE OF ROCKS. The 

 structure of rocks relates to the arrange- 

 ment of their parts, viewed on a larger 

 scale than that of their texture. Struc- 

 ture is said to be massive, when the rock 

 presents no internal division into plates, 

 prisms, or balls, but is of a uniform tex- 

 ture over a great extent ; prismatic or 

 columnar, when amass of a rock is inter- 

 nally divided by fissures into prisms of 

 various sizes or forms, as in basalt, 

 greenstone, and porphyry ; tabular, when 

 a rock is composed of parallel plates, 

 separated by regular seams ; globular, 

 when globular masses of large size are 

 imbedded in a substance of the same 

 nature. 



STRUMA. Bourrelet. A dilatation 

 of the petiole of a leaf, at the extre- 

 mity where it is connected with the 

 lamina. Also, a dilatation at tne base of 

 the sporangium of mosses. 



STRUTHIO'NIDiE {struthio, the 

 ostrich). A natural family of terrestrial 



