DIA 
♦►ight lines, passing through the several 
points ascertained on the line of sines, to 
the quadrant B D ; these will cut the chord 
subtending that quadrant, and give thereon 
a line of latitudes, of equal length with tlie 
line of chords, but very differently divided. 
The remaining quadrant CA is to be di- 
vided into six equal parts, viz. of 16° each : 
make the chord C F A, and draw its paral- 
lel tangent G H. Through the several 
points of division on the quadrant, draw 
lines from the centre E to the line G H, 
which will then represent a line of hours : 
one of the extremes will be XII, the other 
will be VI ; the several intermediate places 
of I, II, III, IV, and V, being ascertained 
by the various lines proceeding from E. 
The 6th figure shews part of a dial, con- 
structed by means of the lines of latitudes 
and of hours. Having set off the parallels 
for the substile, and drawn tlie line of VI 
o’clock, set off the latitude of your place 
from A towards B ; taking the measure- 
ment from tlie line of latitudes. Then mea- 
sure the whole extent of your line of hours, 
and, placing one leg of your compasses at 
B, let the other fall wherever it may reach 
on the line C A. Divide the line B C ac- 
cording to the measures on your line of 
hours; and from A draw lines through tlie 
points of division to the hour circle, which 
will thus he truly intersected at the horal 
points. AV-e have before stated, that by 
dividing the quadrant C A, in fig. 4th, more 
minutely, that is, by dividing each of the 
six portions into four, the halves and quar- 
ters of hours may be shewn. 
Having already shewn the modes of con- 
structing those dials which are in ordinary 
use, we must refer the more curious reader 
to Ferguson’s “ Lectures,” for a great va- 
riety of dials, which could not be introduced 
into this work without greatly augmenting 
the volume. He will there find the modes 
of constructing dials by logarithms, and by 
trigonometry; together with many items re- 
lating to the more abstruse parts of our 
subject. We shall briefly add, that the fol- 
lowing general principle governs the forma- 
tion of all dials. Take the words of that 
great luminary of mechanics, the late Janies 
Ferguson, F. R. S. 
“ If the whole earth were transparent 
and hollow, like a sphere of glass, and had 
its equator divided into 24 equal parts, by 
so many meridian semi circles, one of them 
being the geographical meridian of any 
given place, say London ; and if the hoims 
of XII. were marked on the equator, both 
DIA 
on that meridian, and on its opposite otic, 
and all the rest of the hours on the rest of 
the meridians, those meridians would be 
the hour-circles of London; then if the 
sphere had an opaque axis, terminating at 
its poles, the shadow of that axis would fall 
upon every particular meridian and hour, 
when the sun came to the plane of the op- 
posite meridian ; and would, consequently, 
shew the time at London, and at all the 
other places on the meridian of London.” 
DIALECT, an appellation given to the 
language of a province, in so far as it 
differs from that of the whole kingdom. 
The term, however, is more particularly 
used in speaking of the ancient Greek, 
whereof there were four dialects, the Attic, 
Ionic, .®olic,and Doric, each of which was a 
perfect language in its kind, that took place 
in certain countries, and had peculiar beau- 
ties. In Great Britain, besides the grand 
diversity of English and Scotch, almost 
every county has a dialect of its own, all 
differing considerably in pronunciation, ac- 
cent, and tone, although one and the same 
language. 
DIALIUM, in botany, a genus of the 
Diandria Monogynia class and order. Es- 
sential charaeter : calyx none ; corolla five- 
petalled ; stavnina at the upper side of the 
receptacle. There is but one species, viz. 
D. indnm, a tree with alternate pinnate 
leaves, having seven ovate ohlong, acumi- 
nate, petioled, even leaflets, a hand in 
length. Flowers panicled, nodding. Na- 
tive of the East Indies. 
DIALECTICS, in the literaiy history of 
the ancients, that branch of logics which 
taught the rules and modes of reasoning. 
DIALLING lines, or scales, are gra- 
duated lines placed on rulers, or the edge 
of quadi-£Hits and other instruments, to ex- 
pedite the construction of dials. They 
are, 1. A scale of six hours, which is only a 
double tangent, or two lines of tangents 
each of 45°, set together in the middle, and 
equal to the whole line of sines, witli the 
declination set against the meridian alti- 
tudes in the latitude of the place. 2. A 
line of latitude, which is fitted to the hour- 
scale, and is made by this canon. As the 
radius ; to the chord of 90° : : s® are the 
tangents of each respective degree of the 
line of latitudes : to the tangent, of other 
arcs. And then the natural sines of these 
arches are the numbers, which taken from a 
diagonal scale of equal parts, shall graduate 
the divisions of the line of latitudes to any 
radius. The fines of hours and latitudes 
