DES 
503 
D E ft 
dead. Tlits is the same insert which makes 
in wooden furniture those little round holes 
that reduce it to powder. 
3. The viotaceus is a beautiful little insect; 
its elytra are of a deep violet-blue. The 
thorax is covered with greenish hairs ; the 
legs are black. The whole animal being of a 
glittering brilliancy renders it a pleasing ob- 
ject. The larva, as well as the perfect in- 
sect, inhabits the bodies of dead animals. 
4. The fumatus is of a light-brown colour, 
except the eyes, Which are black. It is, 
however, sometimes more or less deep. The 
thorax is margined, and the insect has the 
whole carriage of a scarabauis ; but its an- 
tennre have the character of those of the tler- 
mestifi. This little creature is found in dung. 
It also frequently finds its way into houses. 
5. The ferrugineus is the largest of the 
genus ; its colour te a rusty iron, having many 
oblong, velvety, black spots upon the elytra, 
which give the insect a gloomy, yet elegant, 
appearance. The antennae differ from the 
preceding species ; the last three articula- 
tions being considerably longer, thicker, aild 
not perfoliated. 
The twentv-fivc other species are distin- 
guished by their colour. Many varieties of 
this genus, as well as the larvae, are to be met 
\vith in dried skins, bark of trees, wood, car- 
cases of dead animals, &rc. 
DELI VIS, a name given to all Mahomme- 
dan monks, though of various orders. The 
most noted among them are the bektashi, the 
mevelevi, the kadri, and the seyah. The 
bektashi, who are allowed to marry and live 
in cities and towns, are obliged, by the rules 
of their Order, to visit remote lands, and to 
salute every one they meet with gazel, or 
love-songs ; and with esma, or the invocation 
of the names of God, and humbly to wish 
hint prosperity, which they do by repeating 
the word eivallah, a solemn exclamation of 
the wrestlers, by which the conquered yields 
the palm to the conqueror. The mevelevi, 
so called from Mevelava their founder, are 
Used to turn round for two or three hours to- 
gether with such swiftness, that you cannot 
see their faces ; they are great lovers of mu- 
sic : in their monasteries they profess great 
humility and poverty, and when visited make 
no distinction ofpersons ; they first bring their 
guests coffee to drink ; and, if the ways have 
been dirty, they wash their feet and sandals. 
The kadri, with" a peculiar superstition, ema- 
ciate their bodies ; they go quite naked, ex- 
cept their thighs, and often join hands and 
dance, sometimes a whole (lay, repeating, 
with great vehemence, “ IIu! hu ! hu!” 
(one of the names of God) till, like mad- 
men, they fall on the ground, foaming at the 
mouth, and running down with sweat: the 
prime vizir Kupruli Achvned Pasha, thinking 
this sect unbecoming the Mahommedan reli- 
gion, ordered it to be suppressed ; but, after 
his death, it revived, and is at present more 
numerous than ever, especially at Constanti- 
nople. The seyah are wanderers, and though 
they have monasteries, yet they often spend 
their whole life in travelling ; when they are 
sent out, their superiors impose upon them 
such a quantity of money or provisions, for- 
bidding them to come back till they have 
procured it, and sen., it to the monastery ; 
wherefore when a seyah comes into a town, he 
cries aloud in the market-place, “ A a allah 
«enden,” &c. “ O God ! give me, I pray, 
Yol. I. 
five thousand crowns, or a thousand mea- 
sures of rice.” Many of these dervises tra- 
vel over the whole Mahommedan world, en- 
tertaining the people wherever they come 
with agreeable relations of all the curiosities 
they have met with. There are dervises in 
Egypt, who live with their families, and ex- 
ercise their trades, of which kind are the 
dancing dervises at Damascus. - They are all 
distinguished among themselves by the dif- 
ferent forms and colours of their habits ; 
those of Persia wear blue ; the solitaries and 
wanderers wear only rags of different colours ; 
others carry on their heads a plume made of 
the feathers of a cock ; and those of Egypt 
wear an octagonal badge of a greenish-white 
alabaster at their girdles, and a high stiff cap, 
without any thing round it. 
DESCANT, in the old music, the art of 
composing in several parts. Descant is 
threefold, viz, plain, figurative, and double. 
DESCENSION, in astronomy, is either 
right or oblique. Right descension is an 
arch of the equinoctial, intercepted between 
the next equinoctial point and the intersec- 
tion of the meridian, passing through the 
centre of the object, at its setting, in a right 
sphere. Oblique descension is an arch of the 
equinoctial intercepted between the next 
equinoctial point and the horizon, passing 
through the centre of the object, at its setting, 
in an oblique sphere, 
DESCENT, in general, is the tendency 
of a body from a higher to a lower place. 
Heavy bodies, meeting with no resistance, 
descend with an uniformly accelerated mo- 
tion, for the laws of which see Mechanics. 
Laws of descent of bodies. 1st. Heavy 
bodies, in an unresisting medium, fall with 
an uniformly accelerated motion. For it is 
the nature of all constant and uniform forces, 
such as that of gravity, at the same distance 
from the centre of the earth, to generate or 
produce equal additions of velocity in equal 
times. So that if in one second of time 
there is produced one degree of velocity, in 
two seconds there will be two degrees of ve- 
locity, in three seconds three degrees, and so 
on ; the degree or quantity of velocity being 
always proportional to the length of the 
time. 
2d. The space descended bv an uniform 
gravity, in any time, is just the half of the 
space that might be uniformly described in 
the same time by the last velocity acquired at 
the end of that time, if uniformly continued. 
For as the velocity increases uniformly in an 
arithmetical progression, the whole space de- 
scended by the variable velocity will be equal 
to the space that Would be described with the 
middle velocity uniformly continued for the 
same. time; and this again will be only the 
space that w ould be with the half of the 
last velocity, also uniformly continued for 
the same time, because the last velocity is 
double of the middle velocity, being pro- 
duced in a double time. 
3d. The spaces descended by an uniform 
gravity, in different times, are proportional 
to the squares of the times, or to the squares 
of the velocities. Fbr the whole space de- 
scended in any number of particles of time, 
consists of the sums of all the particular 
spaces or velocities, which are in arithmetic- 
al progression ; but the sum of such an 
arithmetical progression, beginning at 0, and 
having the last term and the number of terms 
3 Hi 
DES 
the same in quantity, is equal to hall the 
square of the last term,, or of the number of 
terms ; therefore the whole sums are as the 
squares of the times, or of the velocities. 
This theory of the descents by gravity was 
first discovered and taught by Galileo,- wlm 
afterwards confirmed the "same by experi- 
ments ; which have often been repeated in 
various ways by many other persons since His 
time, as Grimaldi, lliccioli, Huygens, New- 
ton, and others, all confirming the same 
laws. 
The experiments of Grimaldi and RiccioR 
were made by dropping a number of balls, 
of half a pound weight, from the top of se- 
veral towers, and measuring the times of 
falling by a pendulum. An abstract ot their 
experiments is** exhibited here below : 
Vibrations 
of the 
pendulum. 
The time. 
Space at 
the end of 
the time. 
Space 
descended 
each time. 
5 
10 / 
IS 
20 
25 
n m 
0 50 
1 40 
2 30 
3 20 
4 10 
Rom. feet. 
10 
40 
90 
160 
250 
Rom. feet. 
10 
30 
50 
70 
90 
6 
1 0 
15 
15 
12 
2 0 
60 
45 
18 
3 0 
135 
75 
24 
4 0 
240 
105 
The space descended by a heavy body in any 
given time, being determined by experiment, is 
sufficient, in connection with the preceding 
theorems, for determining every inquiry con- 
cerning the times, velocities, and spaces descend- 
ed, depending on an uniform force of gravity. 
From many accurate experiments made in F.ng- 
land, it has been found that a heavy body de- 
scends freely through 16 feet 1 inch, or 16-J^, 
feet, in the first second of time; and conse- 
quently, by theorem ‘2, the velocity gained at. 
the end of 1 second, is 32.*. feet per second. 
Hence, by the same, and theorem 3, the velocity 
gained in any other time t is 32.*/, and the 
space descended is I6JL2 2 . So that, if v denote 
1 12 
the velocity, and i the space due to the time /, 
and there be put g i= k> ; then is 
v = =x -- . 
_ , _ 
. % v g 
The experiments with pendulums give aR» 
the same space for the descent of a heavy body- 
in a second of time. Thus, in the'latitude of 
London, ‘it is found by experiment, that the 
length of a pendulum vibrating seconds, is just 
39^ inches ; and it being known that the cir- 
cumference of a circle is to its diameter, as the 
time of one vibration of any pendulum is to 
the time in which a heavy body will fall through 
half the length of the pendulum ; therefore, as 
3.1416 * 1 * * 1 * — - — , which is the time of 
3. 1 4 1 6 * 
descending through 192Lj. inches, or half the 
length of the pendulum ; then, spaces being as 
the squares of the times, as — r " l 2 •• 19 9 
S.1416 2 "" TT 
* 193 inches, or 16 feet 1 inch, which therefore 
is the space a heavy body will descend through 
in one second ; the very same as before. 
4th, For any other constant force, instead of 
the perpendicular free descent by gravity, find 
by experiment, or otherwise, the space descend- 
