STA 
Would be balanced by the intervention of a 
given machine, or the proportion of the 
parts of a machine, by which two known 
forces may balance each other. This view 
of the matter introduced a principle, which 
even Gralileo considered as a mechanical 
axiom, viz. that what is gained in force, by 
means of a machine, is exactly compensated 
by the additional time which it obliges 
us tp employ. This is not quite accurate, 
and not only prevents improvement in the 
construction of machines, bnt leads to 
erroneous maxims of construction. The 
two principles of dynamics teach us, that 
there is a certain proportion of the machine 
dependent on the kind and proportion of 
the power and resistance, which enables 
the machine to perform the greatest possi- 
ble work. It is highly proper, therefore, 
to keep separate these two ways of consi- 
dering machines, that both may be im- 
proved to the utmost, and then to blend 
them together in every practical discussion. 
Statics, therefore, is preparatory to the pro- 
per study of mechanics ; but it does not 
hence derive all its importance. It is the 
sole foundation of many useful parts of 
knowledge. This will be best seen by a 
brief -enumeration. 1. It corpprehends all 
the doctrines of the excitement and propa- 
gation of pressure, through the parts of so- 
lid bodies, by which the energies of ma- 
chines are produced. A pressure is exert- 
ed on the impelled point of a machine, such 
as the float-boards or buckets of a mill- 
wheel. This excites a pressure at the pi- 
vots of its axle, which act on the points of 
support. This must be understood, both as 
to direction and intensity, that it may be 
effectually resisted. A pressure is also ex- 
cited at the acting tooth of the cog-wheel, 
on the same axle, by which it urges round 
another wheel, exerting similar pressures 
on its pivots, and on the acting tooth, per- 
haps, of a third wheel. Thus a pressure is 
ultimately excited in the working point of 
the machine, perhaps a wiper, which lifts a 
heavy stamper, to let it fall again on some 
matter to be pounded. Now statics teaches 
us the intensities and direction of all those 
pressures, and therefore how much remains 
at the working point of the machine unba- 
lanced by resistance. 2. It comprehends 
every circumstance which influences the 
stability of heavy bodies; the investigation 
and properties of the centre of gravity ; the 
theory of the construction of arches, vaults, 
and domes ; the attitudes of animals. 3. The 
strength of materials, and the principles of 
STA 
construction, so as to make the proper ad- 
justment of strength and strain, in every 
part of a machine, edifice, or structure of 
any kind. Statics, therefore, furnishes us 
with what may be called a theory of car- 
pentry, and gives us proper instructions for 
framing floors, roofs, centres, &c. 4. Sta- 
tics comprehends the whole doctrine of the 
pressure of fluids, whether liquid or aeri- 
form, whether arising from their weight, or 
from any external action. Hence, there- 
fore, we derive our knowledge of the sta- 
bility of ships, or their power of maintain- 
ing themselves in a position nearly upright, 
in opposition to the action of the Wind on 
their sails. We learn on what circumstances 
of figure and stowage this quality depends, 
and what will augment or diminish it. See 
Dynamics, Mechanics, &c. 
STATION, in practical geometry, &c. is 
a place pitched upon to make an observa- 
tion, or take an angle, or such like, as in 
surveying, measuring heights and distances, 
levelling, &c. An accessible height is taken 
from one station ; but an inaccessible height 
or distance is only to be taken by making 
two stations, from two places whose dis- 
tance asunder is known. In making maps 
of counties, provinces, &c. stations are fixed 
upon certain eminences, &c. of the coun- 
try, and angles taken from thence to the 
several towns, villages, See. In surveying, 
the instl’ument is to be adjusted by the nee- 
dle, or otherwise, to answer the points of 
the horizon at every station ; the distance 
from hence to the last station is to be mea- 
sured, and an angle is to be taken to the 
next station; which process repeated, in- 
cludes the chief practice of surveying. 
STATIONARY, in astronomy, signifies 
the appearance of a planet, when it seems 
to remain immoveable on the same point of 
the zodiac for several days. As tlie earth, 
whence we view the motions of the planets, 
is out of the centre of their orbits, the pla- 
nets appear to proceed irregularly ; being 
sometimes seen to go forwards, that is, 
from west to east, which is called the direc- 
tion ; sometimes to ^o backwards, or from 
east to west, which is called the retrogra- 
dation. Now between these two states 
there must be an intermediate one, where- 
in the planet neither appears to go back- 
wards nor forwards, but to stand still, and 
keep the same place in her orbit ; which is 
called her station : and this will happen, 
when the line that joins the earth’s and pla- 
net’s centre is constantly directed to the 
same point in the heavens ; that is, when 
