EME 



EMK 



&-*innro, in botany. See 



EMERALD. This mineral comes chief- 

 lyfrom Peru; some specimens have been 

 brought from Egypt Dolomieu found it 

 in the granite of Elba. Hitherto it has 

 been found only crystallized. The primi- 

 tive form of its crystals is are gular six-sided 

 prism ; and the form of its integrant mole- 

 cules is a triangular prism, whose sides 

 are squares, and bases equilateral tri- 

 angles. The most common variety of its 

 crystals is the regular six-sided prism, 

 sometimes with the edges of the prism, or 

 of the bases, or the solid angles, or both, 

 wanting, and small faces in their place. 



Crystals short ; lateral planes smooth, 

 terminal planes rough ; colour emerald 

 green, of all intensities ; internal lustre 

 between 3 and 4 ; vitreous ; fracture 

 small, imperfect, conchoidal, with a con- 

 cealed foliated fracture, and fourfold 

 cleavage; fragments sharp-edged; tran- 

 sparency 4 to 2 ; causesdouble refraction ; 

 scratches quartz with difficulty. Specific 

 gravity from 2.600 to 2.7755. 



The fossil here described is the occi- 

 dental emerald, and appears from agtique 

 gems to have been known in the earlier 

 ages, though at present it comes to us on- 

 ly from South America. Vauquelin found 

 it to contain of silex64.5, argil 16, glucine 

 13, oxide of chrome 3.25, lime 1.6, and 

 water 2. The oriental emerald iaa green 

 corundum, of resplendent lustre, supe- 

 rior in hardness to every stone but 

 the diamond, and of the specific gravity 

 of 4. 



EMERSION, in astronomy, is when any 

 planet that is eclipsed begins to emerge 

 or get out of the shadow of the eclipsing 

 body. It is also used when a star, before 

 hidden by the sun as being too near him, 

 begins to re-appear or emerge out of his 

 rays. 



EMERSON (WILLIAM), in biography, 

 a late eminent mathematician, was born 

 in June, 1701, at Hurworth, a village 

 about three miles south of Darlington, on 

 the borders of the county of Durham ; at 

 least it is certain that he resided here from 

 his childhood. His father, Dudley Emer- 

 son, taught a school, and was tolerably 

 proficient in mathematics ; and without 

 his books and instructions, perhaps., 

 his son's genius, though eminently 

 fitted for mathematical studies, might 

 never have been unfolded. Beside his 

 father's instructions, our author was as- 

 sisted in the learned languages by a 

 young clergyman, then curate of Hur- 

 worth, who was boarded at his father's 

 hxmse. In the early part of his life he at- 



tempted to teach a few scholars; but 

 whether from his concise method, for he 

 was not happy in explaining his ideas, or 

 the warmth of his natural temper, he 

 made no progress in his school ; he there- 

 fore soon left it oJF, and, satisfied with a 

 moderate competence left him by his pa- 

 rents, he devoted himself to a studious 

 retirement, which he thus closely pursu- 

 ed, in the same place, through the course 

 of a long life, being mostly very healthy 

 till towards the latter part of his days,, 

 when he was much afflicted with the 

 stone. About the close of the year 1781, 

 being sensible of his approaching dissolu- 

 tion, he disposed of his whole mathemati- 

 cal library to a bookseller at York ; and on 

 May the20th, 1782, his lingering and pain- 

 ful disorder put an end to his life, athis na- 

 tive village, beingnearly 81 years of age, 



Mr. Emerson, in his person, was rather 

 short, but strong and well made, with an 

 open countenance and ruddy complexion* 

 being of a healthy and hardy disposition ; 

 he was very singular in his behaviour, 

 dress, and conversation ; his manner and 

 appearance were that of a rude and rather 

 boorish countryman ; he was of very plain 

 conversation, and seemingly rude, com- 

 monly mixing oaths in his sentences, 

 though without any ill intention ; he had 

 strong good natural mental parts, and 

 could discourse sensibly on any subject, 

 but was always positive and impatient of 

 contradiction ; he spent his whole life in 

 close study, and writing books, from the 

 profits of which he redeemed his little 

 patrimony from some original incum- 

 brance ; in his dress he was as singular 

 as in every thing else ; he possessed 

 commonly but one suit of clothes at a 

 time, and those very old in their appear- 

 ance ; he seldom used a waistcoat ; and 

 his coat he wore open before, except the 

 lower button ; and his shirt quite the re- 

 verse of one in common use, the hind side 

 turned foremost, to cover his breast, and 

 buttoned close at the collar behind ; he 

 wore a kind of rusty coloured wig, with- 

 out a crooked hair in it, which probably 

 had never been tortured with a comb 

 from the time of its being made : a hat he 

 would make to last him the best part of a 

 lifetime, gradually lessening the flaps, bit 

 by bit, as it lost its elasticity and hung 

 down, till little or nothing but the crown 

 remained. 



He often walked up to London when 

 he had any book to be published, revising 

 sheet by sheet himself : trusting no eye 

 but his own, was always a favourite max- 

 im with him. In mechanical subjects, he. 



