The southern press., 1851-06-25
Mechanism, No. VnI.-By Josiah Holbreok

In mathematics an empty cask and stick of
timber are both solids; also, tumbl r of water
and bar Of ron, an empty room and block of
granite, cave and a mountain, perfect vacuum
and mass of platina. TIE terms air, gas, vapor,
liquid. and vacuum have no place in pure mathe-
matics; they belong to chemistry. Any figure
with length, breadth, and thickness is mathe-
NAUTICAL solid. Five such figures are called ere
guIar solids" Three of these are enclosed in
equilateral triangles. Their respective number
of sides are four, eight, and twenty; and they
are hence called tetraedron oclaedron, and icosa-
edron. One ofthe five is enclosed in six squares,
and is hence called hexaedron, or, more CON-
monty, cube. The remaining one of the five
is enclosed in twelve pentagons, or five-sided
surfaces, and called dodecaedron. Of each of
the 'fve regular Solids" the sides, corners,
and edges are all alike No matter which side,
corner, or edge is presented to the eye. the APP
pearance is the same. This is true, and can be
true, of no other plain figure but one of the re-
gular solids fact of great Importance in the
subject of mechanism.
Not long since chemist paid acarpenter nine
dollars for a set Of regular solids, made of some
common wood, say two or three inches in dame
ter. Thousands have been made by children,
as their richest amusement, far superior 10 many
respects and much more instructive, from being
made By the pupils twn hands. Being made
| of pasteboard, the outspread surface is seen,
showing the mode Of combining, rs well as the
| solid in its regular form.
| Not long since box containing the cube,
modified by several sections and combinations,
was procured from France, at the cost of six
dollars Last winter girl seven years old, the
daughter of member Of Congress, made, prin-
cipally under the instruction Of another girl Of
ten years old, set Of illustrations far more
complete in effecfing their object than those
procured from France, though in workmanship
inferior Of course. Topupil and teacher, it need
not be said, the work was amusing instruction,
and instructive amusement With the cube, un-
der several divisions and combinations. the other
regular solids, variously modified, were also
formed by the same young pupil, aided by her
| juvenile teacher.
BY these practical lessons the facts that in an
inch cube are eight half-inch cubes that in a
two-inch cube are eight inch cubes; and that in
a four-inch cube are sixty-four inch cubes, and
| the whole principle Of the ratio of increase in
all solids, become as familiar both TO teacher and
pupil that lead is heavy and CO. k light, or any
other physical truth learnt by repeated expert.
ments. The doctrine Of the cube, thus Familiarity.
because practically and sgreeably learnt, il Of
very great importance, rs being at the foundation
Of thousands of daily business operations, with
that importance greatly increased from the con-
slant and gross blunders ir business. arising
from the general ignorance Of this fundamental
principle Of cubic measure, even among our
most intelligent business men. The five regular
| solids together are at the foundation Of the
beautiful W pnderfu, and instructive science Of
cry,tallography, as they ere of natural and arti.
fetal mechanism generally, rs exhibited in the
works Of God and man. One or two hundred
dollars are frequently p id for models Of crys-
tails imported from France
ExPERInEST-The clerk Of steamboat once
charged for pile Of rope for passing cars on
an inclined plane. accord ng TO his measure.
ment, one-fourth Of the price intended; not hav.
Jog learnt the difference between an eight foot
cube and eight cubic feet, or other mysteries OF
the cube--also locked up from thousands h.
whom j would be we'll If they were spread out
in broad day light.