TAB 



TAG 



with the assumption of that which is 

 sought as if it were given, a chain of rela- 

 tions is pursued which terminates in 

 what is given (or may be obtained) as if 

 it were sought. The term Synthesis de- 

 notes a process in which the series of 

 relations exhibited commences with what 

 is given, and ends with what is sought. 

 Consequently analysis is the instru- 

 ment of invention, and synthesis that of 

 instruction. See Analysis. 



Synthesis, chemical. The formation of 

 any body by combination of its elements, 

 as opposed to analysis, or the resolution 

 of a body into its component parts. In 

 the analytic operation, a portion of water 

 is separated, by means of galvanism, into 

 the two elementary gaseous bodies, 

 oxygen and hydrogen; in the synthetic 

 operation, these two gases are again 

 made to combine, by means of the elec- 

 tric spark, and a portion of water is 

 again produced. 



SYRINGE (o-upt7f, a pipe or tube). 

 The common squirt, or hand-syringe, con- 

 sists of a cylinder or barrel, furnished 

 with an accurate piston ; at the end of 

 the barrel is a short suction-pipe ; there 

 is no valve. The action of the atmo- 



spheric pressure is the same as in the 

 suction-pump (see Pump). The water 

 which is raised into the barrel is driven 

 thence into the suction-pipe, and pro- 

 jected into the air by mechanical force. 

 The act of respiration, of suction by the 

 mouth, of drinking, of smoking, &c., 

 may all be explained by reference to the 

 same principle. 



SY'RPHID^. A family of dipterous 

 'insects, belonging to the section Atheri- 

 cera, named from the genus syrphus, and 

 closely resembling the wasps and hum- 

 ming-bees. 



SYSTEM (o-yo-rnjua, a whole com- 

 pounded of several parts). A harmoni- 

 ous arrangement of bodies with respect 

 to one another, and of the laws by which 

 their motions, functions, or develop- 

 ments are supposed to be regulated. See 

 Hypothesis. 



SYZYGY [cv^vyia, union). The name 

 given in common to the moon's oppo- 

 sition to, and her conjunction with, the 

 sun. The quadratures are the positions 

 precisely intermediate between the syzy- 

 gies ; at new and full moon the moon is 

 in her syzygies ; at half moon, in her qua- 

 dratures. See Phases and Quadrature. 



TABA'NID^. The Gad-fly tribe; a 

 family of dipterous insects, belonging to 

 the section of Tanystoma, and distin- 

 guished by their powers of perforating 

 the skin and sucking the blood of vari- 

 ous quadrupeds, and even of man. 



TABASHEER. A siliceous substance 

 found in the joints of the bamboo, some- 

 times fluid, but generally in a concreted 

 state. In foreign countries it is termed 

 bamboo milk, salt of bamboo, and bamboo 

 camphor. The word is derived from the 

 Persian scher, or the Sanscrit kschirum, 

 signifying milk. 



TABLE-LAND. An elevated plain 

 rising abruptly from the general level of 

 the country, and being, as it were, the 

 broad and horizontal, or gently undulat- 

 ing top bf an immense mountain, as the 

 Nilgherry district of India. Sometimes 

 there are several such plains placed one 

 upon another, at least on one or two 

 sides, when they are called platforms or 

 terraces, as those on the eastern slope of 

 the Cordillera of New Mexico. 



TABLE-LAYERS. This term is ap- 

 plied by geologists to extended plates of 

 327 



rock, not divided into parallel laminae. 

 Dr. MacCullock proposes to call them 

 pseudo-strata. Mr. Bakewell remarks on 

 what he calls the stratiform structure, 

 that many masses of rock, not really 

 stratified, occur divided into parallel 

 planes, by seams or divisions which re- 

 semble those found in regular strata; 

 such planes have not been super-imposed 

 in succession, but are the result of a 

 crystalline arrangement of the mass. 



TABULAR SPAR. Table Spar. An- 

 other name for prismatic augite, a mine- 

 ral occurring in primitive rocks, asso- 

 ciated with brown garnets. 



TABULAR STRUCTURE. A term 

 expressing the geological character of a 

 rock which is composed of paralled plates 

 or tables, separated by regular seams. 



TACHO'METER {rdxo^, velocity, /ue- 

 Tpov, a measure). An instrument in- 

 vented for the purpose of indicating 

 minute variations in the velocity of 

 machines. 



TACHYDRO'MIANS (raxv?, rapid, 

 ^pojLcof, a course). A term applied to a 

 family of wading birds, of which the 



