B A S 



[ 50 ] BAT 



its name from its having been for- 

 merly used as a touchstone in 

 trying the purity of metals : it also 

 was called Lydian stone, from its 

 being found abundantly in Lydia. 

 According to an analysis of it, its 

 constituents are, silica 75 per cent. , 

 lime, magnesia, carbon, and iron. 

 See Lydian Stoue. 



BASILOSATT'BTJS. The name of an 

 enormous fossil reptile, described 

 by Dr. Harlan of Philadelphia. 

 Neither the relation of the basilo- 

 saurus to other species, nor its geo- 

 logical position, has been accurate- 

 ly determined. Mantell. 



BASE, (from basis, Lat. /3a<rt?, Gr. 

 lase, Pr. lasa, It.) 



1. The bottom, or lowest part, of 

 any thing. 



2. In conchology, that part of the 

 shell in univalves by which they 

 are attached to rocks, or other sub- 

 stances ; in multivalves, the oppo- 

 site extremity to the apex. 



3. The substance to which an acid 

 is united; as in oxide of copper, the 

 copper is the base. 



BA'SIN. (bassin, Fr. latino, It.) In 

 geology, large concavities filled 

 with deposits, as the London basin, 

 the Paris basin, &c. are called 

 basins. The surface of the earth 

 is covered with a series of irregular 

 depressions or basins, divided from 

 one another, and sometimes wholly 

 surrounded by projecting portions 

 of subjacent strata, or by unstrati- 

 fied crystalline rocks, which have 

 been raised into hills and moun- 

 tains of various degrees of height, 

 direction, and continuity. This 

 disposition in the form of basins, 

 which is common to all formations, 

 has been more particularly ob- 

 serve^, in the carboniferous series, 

 from the beds of coal contained 

 therein having been wrought 

 throughout their whole extent. In 

 consequence of this basin-shaped 

 disposition of the carboniferous 

 strata a most beneficial result 



obtains, namely, that these strata, 

 which an uninterrupted inclination 

 in one direction only would soon 

 have plunged into depths inacces- 

 sible to man's greatest efforts, are, 

 by their being placed around the 

 circumference of the basin, all 

 brought sufficiently near the sur- 

 face to be attainable, and are thus 

 made subservient to his benefit and 

 comfort. 



BA'SSET. A term, used by miners, to 

 express an upward slanting direc- 

 tion of a vein, from below to the 

 surface. 



2. The mergence of strata in suc- 

 cession from each other. 



The angle of inclination between 

 these planes and that of the horizon, 

 is called their dip or pitch. 



BA'SSETTING. Slanting upwards. 



BATH- STONE. A species of limestone, 

 called also Bath- oolite. This mem- 

 ber of the oolite formation has 

 been called the great oolite ; it is 

 of considerable thickness, and 

 yields an abundant supply of free- 

 stone for building. It has obtain- 

 ed the name of oolite from its 

 being composed of small rounded 

 grains, or particles, supposed to 

 resemble the roe of a fish. Bath- 

 stone consists of minute globules, 

 cemented together by yellowish 

 earthy calcareous matter, and a con- 

 siderable portion of broken shells. 

 Each of the little grains, rarely 

 exceeding the size of a pin's head, 

 would, if broken open, be found to 

 be composed of concentric coats or 

 shells, sometimes hollow in the 

 centre, sometimes enveloping a 

 small grain. When these grains 

 are larger, and of the size of peas, 

 the rock is called Pisolite, or Pea- 

 stone. When first quarried, Bath- 

 stone is soft, but it soon becomes 

 hard by exposure to the atmosphere. 



BATH- OOLITE. See Bath-stone. 



BATEA'CHIA. (from fiaT-pa^o?, a frog, 

 Gr.) The second order of the 



