New-York tribune., 1841-12-14

tubes backward and forward Though the wsteF IN
the boiler Until. II finally passes through into the
chimney: beng impaired 10 the X IL course
The stssr prodHcei nuds is way 70 The steam or
valve box which contains sliding plce BY which
eirher of the valves can be opened and the other
closed at pleasure. Suppose the steam he let IN
over the piston. it will force 1t downward; when
Il reaches the bottom the steam IS admitted below
i and il Is thu, raised again. In this WAY the Side
valve admits the steam on each side alternately
In the mean time valve : opened by when TIE
steam above the piston make- IT. e>caps and passes
INTO the condenser where i "a reiszled with wnter
But II this process wcrs allowed to 90 On with no
provision made 10 assist II. the condenser would
become chokcd with the hot water produced from
the steam To avoid this pump Is furnished
called the air pump. The OBJECT OF which !, to ara"
the water from the condenser. W hen The piston
Of the air pump ssccnds it opens valve drawing
the water from the condenser into th- ves>al be!o"
II when II desccnds il close, the valve ana thus
the water cannot return. The siston then comes
in contact with the water which Immediately passes
through valves in the piston; when it ascends
these close and the piston lifts it up, drives 1t
through pipes into forcing pump which carries
it into "a cistern. 1t Is not deposited here for no.
thing, a. will be seen hereafter.
Il Ia essential that the condenser be kept cold;
therefore common pump i. provided to draw up
cold water for lis supply.
In order to impart rotary motion to the snaii
the force Of the steam exerted In the rise and tall
# the piston. Is applied by contrivance called
parallel motion 10 a beam placed upon pivot
which raises and depresses a rod attached to
crark tha, act, like a mans arm. There are two
positions Of the arm ia which ise moving power Is
without effect; one is where the Is directly
above the centre OF the shaft nsd the other whers
nj. directly below it, In both these the only
effect produced Is pressure against the axle and
The Engine u in mechanical dilemma In all
ether positions the power will be greater IN pro-
portion The cra'k approaches horizontal, IN
which position il will De greatest. We see thu'
that the power exeited by the Engine will be IRE
gular and in consequence the motion produced VIII
not be uniform. This Is remeded by very sln-
pie contriyance which depends for its ificency
upon ono o.; the common properties III matter.
heavy wheel Is provided winch By its revolving mo-
ton renders the action of the Engine steady and
constant. When the arm Is in lis most favorable
position the engine Is partly employed IN driving
the machinery and partly in turning the wheel 10
which a portion OF its power Is thus impaired
When the arm comes round to the position in
winch it has no Stficscy the power formerly dePo-
>itcd in the wseel comes to relief and carries
trout of its diffculty-and throws up the arm into
il, position of power so that between ths Engine
ard the iy-whecl there is continued interchange
OF power.
The velocity of the Engine will Of course vary
with the work TO be done tho resistance IN
creases the velocity will diminish But II is de-
,reblc To keep the velocity Uniform, and tins Is
done BY A costfvance called the rOreTnOr The
object Is 10 vary the supply of steam according TO
the velocity power required. For this purpose
two heavy balls are suspended from perpendicu-
lar which is attached to the iiy-wheel VI course
they are so suspended TO dlverge from each ohcI
and from the perpendicular when the velocity 10
Increased and falls toward,thc perpendicular when
1t is diminished These balls attached to II
combination Of levers which turn valve in the
passage from the boiler TO the steam-box. When
tae steam is too high. u swter motion will be given
TO tho engine Of course the balls will whir with
greater velocity and will diyerge, which will cause
the lever to partly shut the valve in the passage
which will shut off part of the steam and OF course
diminish the Engines velocity When the steam
low. precisely the opposite effect will be pro-
duced This is an invention of great beauty and
regularity; far efficient in is operation than
any manipulation could be. In early times the
same result was produced witE much less certainty
bv having man TO watch and open or close the
valve as he though, necessary. In examining the
fad this 10 be true; that in proper ION n the Ia
teect is quick 30 i. the man untitled for any mano'
toneus employment.
NAV observe that steam by condensation pro-
ducr. Vacuum as may be shown ~ filling glass
tube with steam. placing one end in water and al
lowing the steam to condense. The water will
Immediately Use in the tube-showing that IL Is
perfect vacuum.
1t IS oil the utmost importance that the water he
kept al proper level in the boiler in order that
the engine may uniform power. In the
earliest engines the same continuance was adopted
which Is now in use, although others have been
added TO make it more perfect. .wo tubes de-
,cend into the boiler, the lower ends OF each being
osen and the upper ends closed by stoFcock.
One of them descend below the proper level and The
other stops above IT, Ii the csck OF the short tube
be opened and steam ru.hss out, you are told that
the water is not too nigh if you open the long one
and cater IS forced By tho pressure OF the steam
upoH it. surface you know that 1t /. not too low
You know then that all Is right. But ii on opening
the short tube water rushes OUT you know 1t IL TOO
nigh; if the long one be opened and steam rushes
out sou know the water is too low You Anow
then either that the engine feeding or that
il has TOO much already. To the mouths OF these
tubes whistle was formerly attached, SO thst
the engine would fairly scream for food whenever
it lacked. The lack TOO great supply was re-
NEEDED BY person whose duty 1t WAS TO listen for
the signal.
But Watt introduced a Continuance y hich super
seeded all attention. By enabling the engine to feed
itself, with proper quantity aad ct the proper time
"a practice when it would be well if mere nteili-
gent being. than the Steam Engine would follow.
Upon the surface OF the water in the boiler va.
placed hoat mi. is attached 10 rod which
passes up and Is attached 10 the end of lever TO
the other arm OF which is suspended weight which
nearly but not quite balances the float 10 ths
same arm i. attached wire which de'cends int
the cistern which receives the water from the con-
danser 2. We hay- slready seen When The wa.