TUB 



TUN 



titious : it is the statement that is either 

 "true" or "false," The "true" cause 

 of any thing, is a common expression ; 

 meaning " that which may with truth 

 be assigned as the cause." The senses 

 of falsehood correspond. Whately. 



TRYMA. The botanical designation 

 of a syncarpous fruit, which is superior, 

 by abortion one-celled, one- seeded, with 

 a two-valved indehiscent endocarp, and 

 a coriaceous or fleshy valveless sarco- 

 carp, as in walnut. 



TUBE. The surface of a tube is gene- 

 rally a cylinder, but this word may be 

 made use of in mathematics. When a 

 tube is bent, there is no distinct geome- 

 trical name for it, but the following defi- 

 nition might do very well : let a surface 

 be called a tube when it is formed by a 

 circle which moves with its centre upon 

 a given curve, and its plane always per- 

 pendicular to the tangent of that curve. 

 This would include the straight tube, or 

 common circular cylinder, and every 

 species of bent tube. — Pen. Cycl. 



TUBE OF SAFETY. A tube open 

 at both ends, inserted into a receiver, the 

 upper end communicating with the ex- 

 ternal air, and the lower being immersed 

 in water. Its intention is to prevent 

 injury from too sudden condensation or 

 rarefaction taking place during chemical 

 operations ; for, if a vacuum be produced 

 within the vessels, the external air will 

 enter through the tube ; and if air be 

 generated, the water will yield to the 

 pressure, being forced up the tube. 

 Thus, too, the height of the water in the 

 tube indicates the degree of pressure 

 from the confined gas or gases. 



TUBER. An annual thickened sub- 

 terranean stem, provided at the sides 

 with latent buds, from which new plants 

 are produced, as in the potato. When 

 very small it is called tubercle. 



TUBI'COL.^: {tubus, a tube, colo, to 

 inhabit). An order of Annellida, or red- 

 blooded worms, enclosed in an elongated 

 tube, which is formed either by the ag- 

 glutination of foreign matters, or by the 

 secretion of calcareous matter resembling 

 that of the shells of certain bivalves. 

 These are the Pinceaux de Mer of the 

 French. 



The term Tubicola also denotes a 

 family of Spiders, which enclose them- 

 selves in a silken tube, strengthened ex- 

 ternally by leaves or other foreign sub- 

 stances. 



TU'BICORNS {tubus, a tube, cornu, 

 a horn). A family of the Ruminantia, in 

 349 



which the horns are composed of a horny 

 axis covered with a horny sheath. 



TUBIPO'RIDtE {tubus, a tube, porus, 

 a pore). A class of polyps, enclosed in a 

 calcareous or coriaceous sheath or tube, 

 from the orifice of which the polyp is 

 protruded when in search of prey. These 

 are called vaginated-polyps. 



TUBITORITES. The name given to 

 the fossil species supposed to belong to 

 iubipora. 



TU'BIVALVES {tubus, a tube, vahce, 

 folding-doors). Tubicolidce. A desig- 

 nation of those bivalves which are fur- 

 nished with a testaceous tube, as teredo. 

 The animals of this family are borers, 

 burrowing in stone, wood, and even in 

 thick shell ; but some, nevertheless, live 

 in the sand. 



TU'BULATURE {tubulus, a little 

 tube). The mouth, or short neck, at the 

 upper part of a tubulated retort. The 

 long neck is called the beak. 



TU'BULIBRANCHIA'TA {tubulus, a 

 little tube, hranchiiB, gills). An order of 

 gasteropods, the shells of which consist 

 of long and irregular tubes usually fixed 

 to foreign bodies, but having the earliest 

 formed portion twisted into a few spiral 

 curves, as in vermetus. 



TU'BULIPO'RID^. A family of the 

 Polypiaria solida of Blainville, who de- 

 scribes them, as animals contained in 

 cells of a tubular figure, with a round 

 mouth, which are accumulated irregu- 

 larly, so as to form an attached solid 

 polyparium. The animals are known 

 only in the genus tubulipora 



TUFA, or TUFF, VOLCANIC. A 

 variety of volcanic rock, of an earthy 

 texture, seldom very compact, composed 

 of agglutinated fragments of scoriae and 

 loose materials ejected from volcanoes. 



1. Tufa, calcareous. A porous rock 

 deposited by calcareous waters on their 

 exposure to the air, and usually contain- 

 ing portions of plants and other organic 

 substances incrusted with carbonate of 

 lime. The more solid form of the same 

 deposit is called travertin, into which it 

 passes. 



2. Tufa, trachytic. Beds and irregular 

 deposits of conglomerate, composed of 

 fragments of trachyte and other volcanic 

 substances, are often abundant in vol- 

 canic districts. When reduced to the 

 state of sand or powder, they form beds 

 of tufa, analogous to those of the trap 

 series. 



TUNGSTEN. A Swedish term, sig^ 

 nifying heavy stone, and applied to an 



