EME 
which he wrote good treatises, though in a 
rough and unpolished style and manner. 
He was not remarkable, however, for ge- 
nius or discoveries of his own, as his works 
hardly shew any traces of original inven- 
tion. He was well skilled in the science of 
music, the theory of sounds, and the various 
scales both ancient and modern ; but he 
was a very poor performer, though he could 
make and repair some instruments, and 
sometimes went about the country tuning 
harpsichords. 
The following is the list of Mr. Emer- 
son’s works, all of them printed in 8vo., ex- 
cepting his “ Mechanics ” and his “ Incre- 
ments,” in 4to., and his “Navigation” in 
12mo. 1. The Doctrine of Fluxions. 
2. The Projection of the Sphere, Ortho- 
graphic, Stereographic, and Gnomonical. 
3. The Elements of Trignometry. 4. The 
Principles of Mechanics. 5. A Treatise of 
Navigation on the Sea. 6. A Treatise on 
Arithmetic. 7. A Treatise on Geometry. 
8. A Treatise of Algebra, in two books. 
9. The Method of Increments. 10. Arith- 
metic of Infinities, and the Conic Sections, 
with other Curve Lines. 11. Elements of 
Optics and Perspective. 12. Astronomy. 
13. Mechanics, with Centripetal and Cen- 
trifugal Forces. 14. Mechanical Princi- 
ples of Geography, Navigation, and Dial- 
ling. 15. Commentary on the Principia, 
with the Defence of Newton. 16. Tracts. 
17. Miscellanies. 
EMERY, a stone of the ruby family, of 
which three kinds are usually distinguished in 
commerce ; the Spanish, red, and common 
emery. The first sort is found in the gold mines 
of Peru, and being judged a kind ofmarcasite 
of that rich metal, is prohibited to be export- 
ed. The red emery is found in copper mines, 
and the little there is of it in England comes 
from Sweden and Denmark. The common 
emery is taken out of iron mines, and al- 
most the only sort used in England ; it is of 
a brownish colour, bordering a little on red, 
exceedingly hard, and in consequence diffi- 
cult to pulverize. The English are the only 
people who have the art of reducing com- 
mon emery into powder, and thus send it to 
their neighbours. Of the powder, the most 
subtile and impalpable is the best ; as to the 
stone, it should be chosen of a high colour, 
and as free of the rock as possible. 
The consumption of emery is very consi- 
derable among the armourers, cutlers, lock- 
smiths, lapidaries, masons, and other me- 
chanics ; some of whom use it to polish and 
burnish iron and steel works; others, to 
EMP 
cut and scallop glass, marble, and precious 
stones. 
EMETIC, a medicine which induces vo- 
miting. 
Emetic tartar, the old name for tartrite 
of antimony. 
EMOLLIENTS. See Pharmacy. 
EMPETRIJM, in botany, heath, a genus 
of the Dioecia Triandria class and order. 
Natural order of Erica', Jussieu. Essential 
character: male, calyx three-parted ; corolla 
three-petalled ; stamens long : female, calyx 
three-parted ; corolla uiree-petalled ; styles 
nine; berry nine-seeded. There are two 
species ; viz. E. album, white-berried heath, 
and E. nigrum, black-berried heath, crow 
or crake berry. These are low shrubs, sel- 
dom propagated in gardens, unless for va- 
riety’s sake. They are natives of wild 
mountains, where the soil is heathy and full 
of bogs. 
EMPIS, in natural history, a genus of in- 
sects of the order Diptera. Generic cha- 
racter : mouth with an inflected sucker and 
proboscis; sucker with a single-valved 
sheath and three bristles; feelers short, fili- 
form ; antennas setaceous. These minute 
insects live likewise by sucking out the 
blood and juices of other animals. There 
are about 30 species. One of the most 
common species is the E. livida, which is a 
brownish fly ; the wings are transparent, with 
dark veins. They are observed in fields 
and gardens. E. borealis, is of a more slen- 
der form than the common window fly, and 
of a blackish colour, with large, broad, oval 
wings, of a brown colour, and rufous legs, 
varied with black. 
EMPLASTRUM, in pharmacy, a com- 
position for external use, generally spread 
upon leather, linen, or some other conveni- 
ent thing before it is applied. See Phar- 
macy. The following is a recipe for making 
the Ladies’ Court Plaster : “ Dissolve five 
ounces of isinglass in a pint .of water, and 
having ready a quantity of thin black sarse- 
net, stretched in a proper frame, apply the 
solution warm with a brush equally over the 
surface. This is to be repeated, after it is 
dry, two or three times.” Some give it a 
coat of gum benzoin dissolved in alcohol - 
but this is injurious rather than beneficial. 
EMPLEURUM, in botany, a genus of 
the Monoecia Tetrandria class and order. 
Natural order of Aggregate. Rutaee*, 
Jussieu. Essential character: male, calyx 
four-cleft; corolla none: female, calyx four- 
cleft, inferior; corolla none; stigma cylin- 
dric, placed on the lateral toothlet of the 
