THY 



715 



TID 



tals of iron pyrites, of a cylindrical form, 

 found in the chalk beds: also fossil echi- 

 nites, of the family Cidaris. 



THL-H'DER-HOUSE. An instrument em- 

 ployed in electrical experiments, to illus- 

 trate the manner in which buildings re- 

 ceive damage by lightning. 



Tur RLS. Short communications between 

 the adits in mines. 



THTRS'DAY. The fifth day of the week. 

 Ilwr's-day, the day consecrated to Thor 

 (q-v.). 



THUS. In pharmacy, frankincense, from 

 Buaa, to sacrifice. See BALSAM and FRAN K- 



IKCENSE. 



THWARTS. Among seamen, Ac., the 

 benches of a boat, on which the rowers sit. 



THYM'ELB, &-JU.O.Y,. The place in the 

 Greek theatres where the musicians were 

 seated. These were called Thymelici, in 

 consequence. 



THYM'IAM. Musk-wood, from Buu.cn, 

 odour, because of its odoriferous smell. 

 Thymiam is a bark (supposed to be of the 

 liquid storax-tree), brought in small 

 brownish-grey pieces from Syria, and 

 some other oriental parts. It has an 

 agreeable balsamic smell, not unlike 

 liquid storax, and a subacid, bitterish 

 taste. 



THYM'US. Thyme. 1. A genus of plants. 

 Itidynamia Gymnospermia. Name from 

 Bvuat. odour, because of its fragrant smell. 

 The wild and the basil thyme are the 

 only two species indigenous to Britain : 

 our garden thyme belongs to the south of 

 Europe. The exotic species, of which 

 there are 23 known, are mostly hardy and 



permanent, though small plants. 2. In 



surgery, a small, fleshy, indolent tubercle, 

 like a wart, arising about the anus, re- 

 sembling the flower of thyme. 3. In 



anatomy, a glandular body, situated be- 

 hind the sternum, in the duplicature of 

 the mediastinum. It is large in the foetus, 

 but constantly diminishes after birth till 

 it wholly disappears (generally) in the 

 adult. Its use is unknown. In calves 

 this is called the sweetbread. 



THYN'XCS. In ichthyology, the Tunny, 

 a fish of the Mediterranean, which attains 

 the length of from 15 to 18 feet. From its 

 abundance it constitutes a great source of 

 wealth to Provence, Sardinia, Sicily, &c. 

 It is considered by Cuvier a subgenus of 

 the genus Scomber, Lin. The name is 

 Latin, from the Greek name Butves. 



THYR'OID, from Bvpos, a shield, and 

 i;&es, like. Resembling a shield. Applied, 

 in anatomy : 1. The thyroid cartilage con- 

 stitutes the anterior, superior, and largest 

 part of the larynx, forming the pomum 



Adami, or Adam's apple, in man. 2. 



The thyroid gland is situated upon the 

 cricoid cartilage, trachea, and horns of 

 *he thyroid gland. Its use i not known. 



THYRSE, Lat. thyrsus, a. young sprout- 

 A name, in botany, for a species of inflo- 

 rescence, consisting of a dense and close 

 panicle, bunch, or cluster, more or less of 

 an ovate form. 



THYSANOU'RA. The name of an order of 

 apterous insects, supported by six feet, 

 experiencing no metamorphosis, and hav- 

 ing, besides, particular organs of motion, 

 either on the sides or the extremity of the 

 abdomen. The order comprises the Lepis- 

 mente and Podurellts of Latreille. 



TIA'RA, Tiatfat. 1. An ornament of dress 

 for the head, worn by the ancient Persian 



kings,nobles, and priests. 2. The pope's 



triple crown. The tiara and the keys are 

 the badges of the papal dignity : the tiara 

 marks the civil rank of the pope, and the 

 keys his ecclesiastical Jurisdiction. It was 

 originally a round hi$h cap, encompassed 

 first by one crown, and then by another. 



TIB'IA. In anatomy, the largest bone of 

 the leg. The term is supposed to be a 

 corruption of tubia from tuba, a tube, on 

 account of its pipe-like shape. 



TIB'IAL. Belonging to the tibia, as the 

 tibial arteries, which are the principal 

 branches of the popliteal artery. 



Tic DOLOUREU'X. A French term sig- 

 nifying a painful spasm, and used to desig- 

 nate facial neuralgia. 



TICK. 1. In entomology, see ASCARCS. 



2. In manufactures, Tick or Ticken is a 



strong textile fabric, used as covering to 

 hold the feathers, down, or other mate- 

 rials of which beds are made. 



TIDES. In hydrography, the alternate 

 ebb and flow of the sea, -which takes 

 place twice in 24 hours, 56 m., 28 sec. of 

 solar time. The tides depend on the ac- 

 tion of the sun and moon, but their ex- 

 planation is one of the most difficult of 

 astronomical problems. The hypothesis 

 of Sir I. Newton is by no means satis- 

 factory. 



TIDE-GAUGE. A mechanical contrivance 

 for registering the state of the tide con- 

 tinuously. 



TIDE-LOCK. Guard-lock. A lock situ- 

 ated between an entrance-basin a^d a 

 canal, harbour, or river, and forming a 

 communication between them. It is fur- 

 nished with double gates, whereby craft 

 can pass them either way, at all times 

 of the tide. 



TIDE-MILL. Amill consisting of a water- 

 wheel connected with other machinery, 

 and moved by the ebbing and flowing of 

 the tide. Tide-mills admit of great 

 variety in the essential parts of their 

 construction. 1st. The water-wheel may 

 turn one way when the tide rises, and 

 the contrary way when the tide falls. 

 2nd. The water-wheel may be male to 

 turn always in one direction. 3rd. The 

 water-wheel may be made to rise and 

 fall as the tide ebbs and flows. 4& Tho 



