The southern press., 1851-07-09
MECHANISM No x.-By John Holbock.

The sphere, cylinder, and cone are called +" the
three round bodies" They are so called from
the fact that most other round bodies may be
viewed as notifications Of these. The sphere
may be called the "regular curved solid" 1t Is
even more regular than either of the five regular
sohus already named Ii has no distinction of
sides, edges, or corners. 1t presents the same
view, from whatever point examined 1t is a
perfectly rouni body. BY pressing and rolling
the sphere may be changed into two spheroids,
fattcned and heightened, called oblate and
probate The sphere and two spheroids can be
readily illustrated and formed by putty, dough,
exhibited in many vegetables. The turnip,
onion, peach, and cantelope are oblate spheroids.
The plum and watermelon are probate spherods.
The earth is an oblate spheroid, being very
slightly fattened at the poles.
A plane passing through the centre of a
sphere divides it into two hemispheres. These
can be divided again and again, presenting
various interesting divisions of this interesting
mathematical solid. The cylinder is a round
body of uniform diameter and circular ends.
The cone is round body, with one end n
circle, the other point, called the base and
apex The trunks of trees and stems of
grasses are cylinders, or cylindrical the carrot,
beat, and parsnip are cones.
! The cone can be divided in five different
sections. making by these divisions triangle,
circle, ellipse, hyperbola, and parabola. The
properties of these figures are 80 interesting as
to be the subject of distinct science, under the
title Of "CoNIc SECTIONS" This science is suf.
ficient in its details to occupy a volume of
considerable size.
The three round bodies can be brought en-.
tirely within the comprehension Of young chill
dren, say six or eight years old, by the revolu-
tons Of four figures, made Of brass, tin, or iron
The revolut n of circle produces the sphere.
An ellipse revolving around its two diameters
produces the two spheroids, obate and probate.
square or oblong gives a cylinder, and a
triangle the cone These revolutions also give,
clearly and strkingly, some interesting facts
about the earth.
A circle, by different divisions, shows a semi
circle, quadrant, sector, segment, diameter, ra-
due, chord, are tangent, secant, sine, cosine &c,
all important TO be familiar at least TO every
one engaged in business pursuit. BY lathe
any person can form, for his own instruction
and amusement, not only three round bodies,
but innumerable notifications of them, as called
for in the daily purposes of farming, mechanism,
and domestic economy. No other instrument
probably combines so much utility, amusement,
and taste. Many literary and other sedentary
personages provide themselves with lathes, FIRE.
quently the amusement of ladies' ms well as
gentlemen, excellent for boys, and girls too
Il ExpERMEST.---In one building not thou
sand miles from Washington were two schools
In one, pupils were whipped daily and severely
for playing truant in the other they would need
whipping, if at all, to keep them from school
The former was "BooK ScnooL y the latter 8
@WoaKING ScHooL"--usng the hand in aid O
the mind.
DEATH ON THE STAGE.--The following parti
culars Of tragedy, Of which the telegraph ha
already furnished us brief account, are from
the 81 Louis Union Of 18th ult
AT about 9 o'clock and while the second &c
of the drama of Jack Sheppard was progressln!
in the front part of the stage, number of thu
company were arranging for dance N bacl
scene, and of course excluded from view of thu
audience. Mrs. Shea, very cstimable lady 0
the corps, had just completed her toilette, and
entered upon tic stage when she engaged IL
conversation with Mr. Watson, relating to some
minuiie Of the performance. Scarcely, however
had word been uttered when large flat-iror
suspending the lamp from the ceiling, slipped
from its fastenings, ard fell to the ground
striking Nrs. Shea or the top of tne head. She
uttered faint 20 my God and in moment
fell stone dead upon the stage. which was soor