SYS 



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T A L 



systole, Fr.) A term used to signify 

 the heart's contraction. The two 

 movements of the heart are its 

 systole and diastole; by the systole 

 of the heart, or its contraction, the 

 blood is pressed out of the heart 

 and forced into the arteries; by 

 its diastole, the blood is received 

 from the veins into the heart. 



SY'ZIGY. (from avfy<yta t Gr. con- 

 junction; syzygie, Fr.) A term 

 applied to the conjunction or oppo- 

 sition of a planet with the sun. 

 The syzygies of the sun and moon 

 occur at the time of full and new 

 moon; the tides are much increased, 

 and are called spring tides, in the 

 syzygies. 



T 



TABASHEE'E. A silicious secretion, 

 or concretion, found in the joints 

 of the bamboo : by some it has 

 been supposed to be the juice of 

 the plant inspissated and hardened. 

 It is remarkable on account of its 

 peculiar optical properties ; its re- 

 fractive power is between air and 

 water, namely 1*111. The finest 

 varieties reflect a delicate azure 

 colour, and transmit a straw-yellow 

 tint, which is complemental to the 

 azure. When it is wetted slightly 

 with a wet needle or pin, the wet 

 spot instantly becomes milk-white 

 and opaque. The application of a 

 larger quantity of water restores 

 its transparency. The word is 

 from the Persian. The tabasheer 

 found in the green bamboo is per- 

 fectly translucent, soft, and moist ; 

 but on exposure to the atmosphere 

 its moisture evaporates, and it 

 becomes opaque, hard, and of a 

 white or grey colour. 



TA'BTJLAR. (from tabularis, Lat.) 

 Formed in lamina or plates ; hav- 

 ing a flat or square surface ; in 

 large plates. 



TA'BULAR STETJ'CTTJEE. This form of 

 structure consists of parallel plates, 

 separated by regular seams ; it is 

 the consequence of crystallization, 

 and though closely allied to the 

 columnar structure, is not uncom- 



monly confounded with stratifica- 

 tion. 



TA'BTJLAR SPAR. (The schaalstein of 

 Werner ; spath en tables of Haiiy ; 

 prismatischer augit-spath of Mohs.) 

 Called also Wollastonite. A grey- 

 ish-white mineral, occurring mas- 

 sive, and in granular concretions. 

 Lustre pearly ; fracture splintery ; 

 translucent. Specific gravity 2 - 7 

 to 3-2. Its constituents are silica 

 51 '40, lime 45'0, oxide of iron a 

 trace, water 4-0. It occurs in pri- 

 mary rocks in Norway, and other 

 places. 



TJENI'ADA. The second order of 

 Scolecida, according to Busk; it 

 comprises the tape- worm. 



TALC. | (talk, Germ, talc, Fr.) A 



TALCK. ) somewhat fibrous and very 

 commonly foliated mineral, resem- 

 bling mica in its lamellar structure, 

 its laminaB not being elastic as 

 are those of mica, but only flexi- 

 ble. Its colours are white, pale 

 yellow, or greenish. Both its sur- 

 face and powder are unctuous to 

 the touch. It is so soft as to be 

 easily, scratched with the finger- 



. nail. Its lustre is often pearly, or 

 inclined to metallic. It is trans- 

 lucent, and, when divided into thin 

 laminaB, transparent. Specific gra- 

 vity from 2.58 to 2-90. Before 

 the blow-pipe it whitens, its lamina 



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