American telegraph. [volume] (Washington [D.C.]) 1851-1851, 1851-06-27
MECHANISM, No. vIIL-Dr JOSIAH uoLpnooK

MECHANlSM, No SltL--BY JOSIAH HoLBgooK
In mathematics an empty cask and a stick Of
timber are both solids; also, tumber of water
and bar of iron, an empty room and block
OF granite, cave and u mountain, n perfect
vacuum and mass of platina. The terms air,
gas, vapor, liquid, and vacuum have no place in
pure mathematics they belong to chemistry
ANY hgure with length, breadth, and thickness,
Is mathematical solid. Five such figures are
called 'reguidr solids" Three of these are en-
closed IN equiateral triangles. Their respective
NUMBER OF SIDES are four, eight and twenty;
ana they are hence called tetraletlron, octahe-
dron, and icosahedron. One Of the five is en-
closed In six squares, and is hence called a hex
ahedron, or, more commonly, u cube The
remaining one of the five is enclosed in twelve
pentagons, or fve-sded surfaces, and called a
dodecahedron. Of each Of the g five regular
solids" the sides, corners, and edges are all
ahke;z q matter which side, corner or edge, is
presented to the eye, the appearance is the same
This is true, and can be true Of no other plain
inquire but one of the regular solids--a fact of
great Importance in the subject of mechanism
Not long since chemist paid carpenter
nine dollars for set Of regular solids, made Of
some common wood, say two or three inches in
diameter. Thousands have been made by chill
dren as their richest amusement, far superior
in many respects, and much more instructive,
from being made by the pupils own hands.
Beng made Of pasteboard, the outspread
face is seen, showing the mode of combining,
as 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 efecting their object than those
procured from France, though in workmanship
inferior Of course. To pupil and teacher, it
need not be said the work was amusing in
struction, and instructive amusement. With
the cube, under several divisions and combna-
tions, the other regular Solids variousy mod-
fed, were also formed by the same young pupil,
and by her Juvenile teacher.
By these practical lessons the facts, that in an
inch cube are eight halfinch cubes; that in q
two-inch cube are eight inch cubes; and that
in n four inch cube sixty-four inch cubes,
and the whole principle of the ratio of increase
in all solids, become as familiar both to teacher
and pupil as that lead is heavy and cork light,
or any other physical truth learned by repeated
experiments. The doctrine of the cube thus
familiarly, because practically and agreeably
learned, is of very great Importance as being at
the foundation of thousands of daily business
operations, with that Importance greatly in
creased from the constant and gross blunders in
business arising from the general ignorance of
this fundamental principle of cubic measure,
even among our most intelligent business men.
The five regular solids are at the foundation Of
the beautiful, wonderful, and instructive science
of crystallography, as they are of natural and
artificial mechanism generally, exhibited in
the works of God and man. One or two hun
dred dollars are frequently paid for models of
crystals imported from France.
E1perimenL- THE clerk of q steamboat once
charged freight for pile of rope for passing
an inclined plane, according to his mea-
surement, one-fourth of the price intended; not
having learned the difference between an eight
foot cube and eight cubic feet, or other mystic
ries Of the cube; also locked up from thousands
to whom it would be well if they were spread
out in broad daylight.
We think it due to the estimable author of
these essays to place in our columns the an
nexed testimony to their value, from the hon
orable Senator Shields, of Illinois, for which
purpose we solicited a copy of the letter
BELIEvILLE, June IL, 1851
Dear Sir: I have just received the first num-
Der of your essays on " Mechanism" 1t will
give me great pleasure to contribute to its cir
culation in this State. hope to see your essays
on L" Geology and % Mechanism in every com
mon school in this State, for the purpose of
primary instruction 1t would be impossible to
find greater quantity of useful information in
a smaller compass. Yours respectfully,
JAS. SHIELDS.
JOSIAH HoLBRooK, esq, Washington.
There is hardly n more common mistake than