VEL 
by moving parallel to itself, is supposed to 
generate a rectangle, always equal to the 
surface. The velocity with which a solid 
flows, may be measnred by the velpcity of 
a given plain surface tliat, by moving paral- 
lel to itself, is supposed to generate an 
erect prism, or cylinder, always equal to 
the solid. The velocity with which an an- 
gle flows, ts measured by the velocity of a 
point, supposed to describe the arc of a 
given circle, which subtends the angle, and 
measures it. All these velocities are mea- 
sured at any term of the time of the mo- 
tion, by the spaces which would be describ- 
ed in a given time, by these points, lines, 
or surfaces, with their motions continued 
uniformly from that term. The velocity 
with which a quantity flows, at any term of 
the time, while it is supposed to be gene- 
rated, is called its fluxion. See Fluxions. 
Velocity of bodies snorting in curtes. 
According to Galileo’s system of the fall 
ef heavy bodies, which is novv universally 
admitted among philosophers, the velocities 
of a body falling vertically are, at eadi mo- 
ment of its fall, as the square roots of tlie 
heights from whence it has fallen ; reckoning 
from the beginning of the descent. And 
hence he inferred, that if a body descend 
along an inclined plane, the velocities it 
has, at the different times, will be in the 
same ratio: for since its velocity is all 
owing to its fall, and it only falls as much 
as there is perpendicular height in the in- 
clined plane, the velocity should be still 
measured by that height, the same as if the 
fall were vertical. The same principle led 
him also to conclude, that if a body fall 
tlirough several cont%uous inclined planes, 
making any angles with each other, much 
like a stick when broken, the velocity 
would still be regulated after the same 
manner, by the vertical heights of the dif- 
ferent planes taken together, considering 
the last velocity as the same that the body 
would acquire by a fall through the same 
perpendicular height. 
This conclusion continued to be ac- 
quiesced in, till the year 1672, when it was 
demonstrated to be false, by James Gre- 
gory, who shows what the real velocity is, 
which a body acquires by descending down 
two contiguous inclined planes, forming an 
obtuse angle, and that it is different from the 
velocity which a body acquires by descend- 
ing perpendicularly through the same height; 
also that the velocity in quitting the first 
plane, is to that with which it enters the 
(econd, and in this latter direction, as ra- 
VEN 
dins to the co-sine of the angle of inclination 
between the two planes. / 
This conclusion, however, it is observed 
does not apply to the motions of descent 
down any curve lines, because the con- 
tiguous parts of curve lines do not form 
any angle between them, and consequently 
nh part of the, velocity is lost by passing 
from one part of the curve to the other ; 
and hence he inters, that the velocities ac- 
quired in descending down .a continued 
curve line, are the same as by falling per- 
pendicularly through the same height. 'This 
principle is then applied, by the author, to 
the motion of pendulums and projectiles. 
Varignon too, in the year 1693, followed 
in the same track, showing that the velocity 
lost in passing from one right lined direc- 
tion to another, becomes indefinitely small 
in the course of a curve line; and that 
therefore the doctrine of Galileo holds good 
for the descent of bodies down a curve 
line, viz, that the velocity acquired at any 
point of the curve, is equal to that which 
would be acquired by a fall through the 
same perpendicular altitude. 
VELVET, a rich kind of stuff, all silk, 
covered on the outside with a close, short, 
fine, soft shag, the other side being a very 
strong close tissue. The nap, or shag, call- 
ed also the velveting, of this stuff, is form- 
ed of part of the threads of the warp, 
which the workman puts on a long narrow- 
channeled ruler or needle, which he after- 
wards cuts, by drawing a sharp steel tool 
along the channel of the needle to the ends 
of the warp. 
VENEERING, or Vaneering, a kind 
of inlaying, whereby several thin slices or 
leaves of fine woods, of different kinds, 
are applied and fastened on a ground of 
some common wood. There are two kinds 
of inlaying: the one, which is the most 
common and more ordinary, goes no fur- 
ther than the making of compartments of 
different woods; the other requires much 
more art, in representing flowers, birds, 
and the like figures. The first kind is pro- 
perly called veneering ; the latter is more 
properly called marquetry. The wood used 
in veneering is first sawed out into slices or 
leaves about a line in thickness; i. e. the 
twelfth part of an inch. In order to saw 
them, the blocks, or planks, are placed up- 
right, in a kind of sawing press. These 
slices are afterwards cut into narrow slips, 
and fashioned divers ways, according to the 
design proposed; then the joints having 
been exactly and nicely adjusted, and the 
