SPE 
§PE 
tlie species, it is plain that the genus and 
specific dilFerence arc the proper and con- 
stituent parts of the species. If we trace 
the progress of the mind still further, and 
observe it advancing through the inferior 
species, we shall find its manner of pro- 
ceeding to be always the same ; since every 
lower species is formed, by superaddiiig 
some new idea to the species next above : 
thus if animal be the genus, by superadding 
the notion of four limbs, we obtain the idea 
of quadrupeds ; if to this we add further, 
the peculiar form and characters which dis- 
tinguish mankind, we get the idea of the 
human species; and by adding the pecu- 
liarities wliich distinguish a particular per- 
son fropi all others, we form the notion of 
an individual, which is called the last spe- 
cies, or species specialissinmm. 
For the use of the genus, species, and 
specific difference in defining things. See 
Definition. 
Species, in logic, is one of the five words 
cglled by Porphyry universals. See Uni- 
versal. 
Species, in rhetoric, is a particular thing, 
contained under a more universal one. 
Species, in commerce, are the several 
pieces of gold, silver, copper, &c. xvhich 
having passed their full preparation and 
coinage are current in public. 
Species, in algebra, the c'.-aracters or 
symbols made use of td represent quantities. 
SPECIFIC, in philosophy, that which is 
peculiar to any thing, and distinguishes it 
from all others. 
Specific, in medicine, a remedy whose 
virtue and effect is pecnliarly adapted to 
some certain disease, is adequate thereto, 
and excris its whole force immediately 
thereon. 
Specific gravity, is that by wdiich one 
body is lieavier than another of the same 
dimension, and is always as the quantity of 
matter under that dimension. As to the 
method of finding the specific gravities of 
bodies. See Hydrostatics. 
SPECTACLE. See Vision. 
SPECTRA, ocular. See Retention. 
SPECTRUM, in ojitics. ■ When a ray of 
light is admitted through a small liole, and 
received on a white surface, it forms a lu- 
minous spot. If a dense, transparent body 
be interposed, tlie light will be refracted, 
in proportion to the density of tiie medium ; 
but if a triangular glass prism be inter- 
posed, tlie Uglit is not merely refracted, but 
it is divided into seven different rays. The 
ray of light no longer forms a luminous 
spot, but has assumed an oblong shape, terj 
minating in semicircular arches, and exhi- 
biting seven different colours. This image 
i.s called the spectrum, and, from being pro- 
duced by the prism, the prismatic spec- 
trum. These different coloured rays ap- 
pearing in different places of the spectrum, 
show that their refractive power is differ- 
ent. Those which are nearest the middle 
are tlie least refracted, and those which are 
the most distant, tlie greatest. The order 
of the seven rays of the spectrum is the fol- 
lowing : red, orange, yellow, green, blue, 
indigo, violet. The red, which is at one 
end of the spectrum, is tlie least, and the 
violet, which is at the other end, is the most 
refracted. Sir Isaac Newton found, if the 
whole spectrum was divided into 360 parts, 
the number of the parts occupied by each 
of the colours to be the following : 
Red 
Orange 
Yellow 
Green 
60 
Blue 
Indigo 
........ 40 
Violet 
These different coloured rays are not 
subject to further division. No change is 
effected upon any of them by being further 
refracted or reflected ; and, as they differ 
in refrangibility, so also do tliey differ in 
the power of inflection and reflection. The 
violet rays are found to be the most reflex- 
ible and inflexible, and the red the least. 
SPECULATIVE, something relating to 
the theory of some art or science, in con- 
tradistinction to practical. 
SPECULUM, a looking glass, or mirror, 
capable of reflecting the rays of tke sun, 
&c. See Mirror and Telescope. 
Speculum, in surgery, an iiistnimeiit for 
dilating a wound, or the like, in order to 
exaniiiie it attentively. 
SPERGULA, in botany, spurrey, a ge- 
nus of tlie Decandria Peiitagynia class and 
order. Natural order of Caryophyllei. Es- 
sential character : calyx five-leaved ; petals 
five, entire ; capsule ovate, one-celled, five- 
valved. There are seven species. The S.ar- 
veusis, corii spiirrey, has linear-furrowed 
leaves, from eight to twenty in a whorl. 
The flowers are small, white, and terminal. 
It is frequent in corn-fields. In Holland it 
is cultivated as food for cattle, and has the 
advantage of growing on the very poorest 
soils, but does not afford a! great deal of 
food. Poultry are fond of the seeds ; and 
the inhabitants of. Finland and Norway 
