5GS 
D I M 
D I A 
D I A 
lawful men, inquire what lands and tenements, 
by ttie death of tlie tenant, came to the king. 
Dyer, 360. pi. 4. 
DEVESTING, in old law-books, the re- 
verse of investing or investiture. See the ar- 
ticle Investiture. 
DEVISE, or device, in heraldry, painting, 
and sculpture, any emblem used to represent 
a certain family, person, action, or quality ; 
with a suitable motto, applied in a figurative 
sense. 
Devise, in law, the act whereby a person 
bequeaths his lands or tenements to another, 
by his last will and testament. The person 
who makes this act, is called the devisor, and 
lie in whose favour the act is made, is termed 
in law the devisee. 
DEVOTION, devotio, a sincere and ar- 
dent worship of the deity. 
DEVOU RING, in heraldry, is when fishes 
are borne in an escutcheon in a feeding pos- 
ture, for they swallow all the meat whole. 
DEW, a dense moist vapour, falling on the 
earth in form of a misling rain. See Mete- 
orology. 
D EXTANS, in Roman antiquity, ten 
ounces, or i-f of their libra. 
DEXTER, in heraldry, an appellation 
given to whatever belongs to the right side 
of the shield, or coat of arms : thus we say, 
bend-dexter, dexter point, & c. 
DIABETES, in physic, an excessive dis- 
charge of urine, which comes away crude, 
and exceeds the quantity of liquids drunk. 
See Medicine. * 
DIACAUSTIC curve, a species of the 
caustic Curves formed byrefraction.Thus if you 
imagine an infinite number of rays BA, BM, 
BD, &c. (PI. Misc-el. fig. 40) issuing from the 
same luminous point B to-be refracted to or 
from the perpendicular MC by the given 
curve AMD, and so that CE, the sines of the 
angles of incidence CME, be always to CG, 
the sines of the refracted angles C MG, in a 
given ratio; then the curve HEN, which 
touches all the refracted rays, is called the 
diacaustic, or caustic refraction. See 
Caustic curve. 
DIACHYLON, in pharmacy, an emol- 
lient digestive plaster. See Pharmacy. 
DIADELPIHA, in the Linnaxm system of 
botauv, a class of plants, the seventeenth in 
order; comprehending all those with papi- 
lionaceous and hermaphrodite Rowers, and 
leguminous seed-vessels. See Botany. 
DIADEM, in antiquity, a head-band, or 
fillet, worn by kings, as a badge of their 
rovaltv. It was made of silk, thread, or wool, 
ami tied round the temples and forehead, 
the ends being tied behind, and let fall on the 
neck. It was usually white, and quite plain, 
though sometimes embroidered with gold, 
and set with' pearls and precious stones. 
In latter times, it came to be twisted round 
crowns, laurels, &c. and even appears to have 
been worn on divers parts of the body. 
Diadem, in heraldry, is applied to certain 
circles or rims, serving to inclose the crowns 
of sovereigns and to bear the globe and cross, 
or the ilower-de -luces for their crest.. 
DLERESIS, in surgery, an operation 
serving to divide and separate the part when 
tin? continuity is a hindrance to. cure. See 
ht'RGEEY. 
Di/EUESis, in medicine, is the consuming 
of the vessels of an animal body. See Medi- 
cine. 
Diuresis, in grammar, the division of 
one syllable into two, which is usually noted 
by two points over a letter, as auia'i. instead of 
auke, dissoliienda for dissolvenda. 
DET.TET.'E, in Grecian antiquity, a kind 
of judges, of which there were two sorts, the 
cleroti and dialiacterii. The former were 
public arbitrators, chosen b) lot to determine 
all causes exceeding ten drachms, within 
their own tribe, and from their sentence 
an appeal lav to the superior. courts. 
DIAGNOSTIC, in medicine, a term 
given to those signs which indicate the pre- 
sent state of a disease, its nature and cause. 
See Medicine. 
DIAGONAL, in geometry, a right line 
drawn across a quadrilateral figure, from one 
angle to another, by some called the diameter. 
Thus ab in plate Miscel. fig. 41. is called a di- 
agonal. It is demonstrable, 1. that every di- 
agonal divides a parallelogram into two equal 
parts. 2. That two diagonals drawn in any 
parallelogram bisect each other. 3. A line 
fg, passing through the middle point of the 
diagonal of a parallelogram, divides the figure 
into two equal pifrts. 4. That the diagonal of 
a square is incommensurable with one of its 
sides. 5. That tbe sqm of the squares of the 
diagonals of every parallelogram is equal to 
the sum of the squares of the four sides. 
DIAGRAM, in geometry, a scheme for 
explaining. and demonstrating the properties 
of any figure, whether triangle, square, cir- 
cle, &c. 
Diagram, among musicians (from the 
Greek). The name given by the antients to 
the table, or model, representing all the 
sounds of their system. 
DIAL, or sun-dial, is a plane, upon which 
lines are described in such a manner, that 
the shadow of a wire, or of the upper edge 
of a plate stile, erected perpendicularly on 
the plane of the dial, may shew the true time 
of the day. The edge of the plate by which 
the time of the day is found, is called the 
stile of the dial, which must be parallel to the 
earth’s axis ; and the line on which the said 
plate is erected, is called the substile. The 
angle included between the substile and stile, 
is called the elevation, or height of the stile. 
Those dials whose planes are parallel to 
the plane of the horizon, are called horizon- 
tal dials ; and those dials whose planes are 
perpendicular to the plane of the horizon, 
are called vertical or erect dials. 
Those erect dials, whose planes directly 
front the north or south, are called direct 
north or south dials; and all other erect dials 
are called dediners, because their planes are 
turned away from the north or south. 
Those dials, whose planes are neither pa- 
rallel nor perpendicular to the plane of their 
horizon, are called inclining or reclining 
dials, according as their planes make acute 
or obtuse angles with the horizon; and it 
their planes are also turned aside from facing 
the south or north, they are called declining- 
inclining or declining-reclining dials. 
The intersection of the plane of the dial, 
with that ot the meridian, passing through 
the stile, is called the meridian of the dial, 
or the hour-line of XI f. 
Those meridians, whose planes pass through 
the stile,, and make* angles of 15, 30, 45, C>6, 
75, and 90 degrees with the meridian of the 
place (which marks the hour-line of 1‘J), are 
called hour-circles ; and their intersection* 
with the plane of the dial, are called hour- 
lines. 
In all declining dials, the substile makes an 
angle with the hour-line of XII ; and this 
angle is called the distance of the substjle 
from the meridian. 
The declining plane’s difference of longi- 
tude, is the angle formed at the intersection 
of the stile and plane of the dial, by two 
meridians; one of which passes through the 
hour-line of XII, and the other through the 
substile. 
We shall now proceed to explain the dif- 
ferent principles of their construction. 
The universal principle on which dialing 
depends. — If the whole earth a P cp (Plate 
fig. 1) were transparent and hollow, like a 
sphere of glass, and had its equator divided 
into twenty -four equal parts by so many me- 
ridian semicircles, a,b,c, d, c,t,g, &c. one 
of which is the geographic al meridian of any 
given place, as London (which is supposed to 
be at the point a); and if the hours of XII 
were marked at the equator, both upon that 
meridian and the opposite one, and all the 
rest of the hours in order on the rest of the 
meridians ; those meridians would be the 
hour-circles of London : then, if the sphere 
had an opake axis, as P E/>, terminating in 
the poles P and p, the shadow of the axis 
would fall upon every particular meridian 
and hour, when the sun came to the plane of 
the opposite meridian, and would conse- 
quently shew the time at London, and at all 
other places on the meridian of London. 
Horizontal dial. — If this sphere was cut 
through the middle by a solid plane AB 
C D, in the rational horizon of London, one 
half of the axis E P would be above the 
plane, and the other half below it ; and if 
straight lines were drawn from the centre of 
the plane, to those points where its circum- 
ference is cut by the hour-circles of the 
sphere, those lines would he the hour-lines 
of a horizontal dial for London: for the sha- 
dow of the axis would fall upon each par- 
ticular hour-line of the dial, when it fell upon 
the like liour-circle of the sphere. 
Vertical dials. — If the plane which cuts 
the sphere he upright, as A F C G (tig. 2), 
touching the given place (London) at E, and 
directly facing the meridian of London, it 
will then become the plane of an erect direct 
south dial ; and if right lines be drawn from 
its centre E, to those points of its circumfer- 
ence where the hour-circles of the sphere 
cut it, these will be the hour-lines of a ver- 
tical or direct south dial for London, to 
which the hours are to be set as in the figure 
(contrary to those on a horizontal dial) ; and 
the lower half E/> of (he axis will cast a sha- 
dow on the hour of the day in this dial, at 
the same time that it would fall upon the like 
hour-circle of the sphere, if the dial-plane was 
not in the way. 
Inclining and reclining dials. — If the plane 
(still facing the meridian) be made to incline, 
or recline, by any given number of degrees, 
the hour-circles of the sphere will still cut 
the edge of the plane in those points to which 
the hour-lines must be drawn straight from 
the centre; and the axis of the sphere will 
cast a shadow on these lines at the respec- 
tive hours. The like will still hold, if the 
