VES 
hy calculation, that the apparent diameter 
of the planet Vesta is only 0.488 seconds, 
and conse< 5 uently, only halt of what I have 
found to be the apparent diameter of the 
fourth satellite of Saturn. This extraordi- 
nary smallness, with such an intense, ra- 
diant, and unsteady light of a fixed star, is 
the more remarkable, as, according to the 
preliminary calculations of Dr. Gauss, there 
can be no doubt that this planet is found in 
the same region between Mars and Jupi- 
ter, in which Ceres, Pallas, ajid Juno per- 
form their revolutions rhund the sun ; that, 
in close union with tliem, it has the same 
cosmological origin ; and that, as a planet 
of such smallness and of so very intense 
light, it is comparatively near ^o the earth. 
This remarkable circumstance will no doubt 
be productive of important cosmological 
observations, as soon as the elements of the 
new planet have been suflficiently deter- 
mined, and its distance from the earth as- 
certained by calculation." 
Much of what is said of Vesta is applica- 
ble to the other small planetary bodies re- 
ferred to in this article. 
VESTRY, a place adjoining to a church, 
where the vestments of the minister are 
kept; also a meeting at such place, where 
the minister, churchwardens, and principal 
men of most parishes, at this day, make a pa- 
rish vestry. On the Sunday before a vestry 
is to meet, public notice ought to be given, 
either in the church, or after divine service 
is ended, or else at the church door, as the 
parishioners come out ; both of the calling of 
the meeting, and also the time and place of 
the assembling of it ; and it is reasonable 
then also to declare for what business tlie 
meeting is to he held, that none may be 
surprised, but that all may have full time 
before, to consider of what is to be pro- 
posed at the meeting. 
VESUVIAN, in mineralogy, a species of 
the Flint genus,; it is of a dark olive-green, 
which passes into a blackish gree n. It oc- 
curs massive, often crystallized. Specific 
gravity about 3.5. Before the blow pipe, 
it melts, without addition, into a yellowish 
and faintly-translucent glass. It is found 
among the exuvise of Vesuvius, in a rock 
composed of mica, hornblende, garnet, and 
calc spar, which Werner imagines to con- 
stitute part of the primitive mass on 
which that volcanic mountain rests. It 
has also been found in Siberia, and in 
Kamtschatka. At Naples it is cut into 
ring'Stoiies, and is sold under various names. 
VIB 
Two specimens have been analyzed by 
Klaproth ; the results are as follow ; 
Ve^uvian of Vesuvius. 
Silica 35.50 
Lime 33.00 
Allumina 22.25 
Oxide of iron 7.50 
Oxide of manganese ... 0.25 
Loss 1.60 
100.00 
Vesuvian of Siberia. 
Silica 42.00 
Lime 34.00 
Allumina 16.26 
Oxide of iron 5 50 
Loss.... 2.25 
100.00 
VESUVIUS, a famous volcano, or burn- 
ing mountain, situated only six miles east of 
the city of Naples, in Italy. See Volcano. 
VIBRATION, in mechanics, a regular 
reciprocal motion of a body, as, for exam- 
ple, a pendulum, which, being freely sus- 
pended, swings or vibrates from side to 
side. Mechanical authors, instead of vibra- 
tion, often use the term oscillation, espe- 
cially when speaking of a body that thus 
swings by means of its own gravity* or 
weight. 
The vibrations of the same pendulum are 
all isochronal ; that is, they are performed 
in an equal time, at least, in the same lati- 
tude ; for in lower latitudes they are found 
to be slower than in higher ones. See Pen- 
nuLOM. In our latitude, a pendulum 39i 
Indies long vibrates seconds, making 60 vi- 
brations in a minute. 
The vibrations of a longer pendulum 
take up more time than those of a shorter 
one, and that in the sub-duplicate ratio of 
the lengths, or the ratio of the square 
roots of the lengths. Thus, if one pen- 
dulum be 40 inches long, and another only 
10 inches long, the former will be dou- 
ble the time of the latter in performing a 
vibration ; for 40 : v' 10 v" 4 : v' 1> 
that is, as 2 to 1. And because the num- 
ber of vibrations, made in any given time, 
is reciprocally as the duration of one vibra- 
tion, therefore the number of such vibra- 
tions is in the reciprocal subduplicate ratio 
of the lengths of the pendulums. 
Vibrations of a stvetched chord, or 
string, arise from its elasticity ; which 
7 ". 
