New-York daily tribune. [volume] (New-York [N.Y.]) 1842-1866, 1865-12-05
EXPANSION AND PROPULsION.

| ALI persons are familiar with the transcendent
achievements of steam, and almost all CONSIDER
them prelusive to others still greater; but wnhs
every one sees what it does, comparatively few per-
cciye how it is done. Ideas Of it that reach ne
further than external features and movements OF an
engine are indefinite, and more or less cloudy ana
chaotic Even with engineers themselves, there
are points in the evolution, treatment, action ana
applications of the fluid far from being lucid ana
sharply defined. Opinions greatly vary. Two ex-
amples may hcre be quoted: one of marked interest,"
to the engineering community, the other OF greater
importance to our national and commercial marine.
l. Economy of expansion by cut-ofs. 2. The vir-
tue Of form in propelling blades. The competing
| engines of the Algonquin and WnoOsh will go Tar
to settle the first, but not the second with under
! shot watcr-whees suspended as paddles over Inc
sides OF those vessels.
| OF the economy of stopping the flow Of steam
into cylinder before the piston reaches its rods,
there il and has been no diversity of opinion the
! fact is palpable, and such has been the uniform
practice since the beginning. The points in dispute
are the extent 10 which the principle is urged and
the amounts of gain claimed. Prevailing opinions,
right or wrong have always governed, aad much
that is due only to reflection and demonstration -
still Welded to popular dogmas, to interest and feel
| ing. Inventors ottener build without data than
With them, and what is worse, their propositions
are too commonly made bases OF speculation All
this is NATURAL at any rate unayodaoe nor Is ", ON
the whole to be regretted that truth IN meehanlca.
as in other departments oil research, naS ~ ."
reached throAh conflicts with interests and error.
Without efforts to attain It, We c9g1d ne.oec 10
prepared 70 receive IT, nor capable of properly APP
preciating it. That which costs little or nothing Id
| held of small account.
Willie warm admirers Of independent cut-ofs
\ of
TO which the advantages are attributed others
glance at what they hold as full counterbalance-
Thus when charge cutoff at one-thlrd drives me
piston through the remaining two.thrds, clean
profit is claimed. To this cool observers say nay;
that against il should be placed the expenditure or
two.thris more power-steam-On the first part of
the stroke than was required, and hence that which
is gained az one point is lost at another; at all
events, that the difference Is rather slight than
serious But may not the surplus force turned on
the first part be recovered and applied to the latter
part? No, not a particle. Misspent force can No
more be recalled than msspent time. II vanIshes
with its action, and no longer exists iet the steam
is still in the cylinder? Granted, but it no longer
possesses the power gone OUT OF ~. IL was intacs
while the piston was stationary, but diminished ~
that gave way before it, At first glance, the loss
NAV not be apparent, but the difficulty yanlsbeS
when il is remembered that communication WITH
the boiler is not closed till the piston has passed
through the cylinder the point fixed on for the cut
u
boiler, and consequently does not appear IN the
cylinder. Could unproductiye or misapplied force,
of any kind be recovered and turned to account,
the economy of creation would be very dihefchs
from what it j..
II would moreover be marvel if additionalpower
could be got out of definite quantity OF steam BY
increasing its ten.on-if onethlrd OF charge al w
fb on the inch we're more effective than atu one at
80 H. As well expect to spin more thread out of q
pound of closely than of loosely packed cotton.
Compression can add nothing 10 the fiber or huid.
The gain, however is ascribed TO economy IN ex-
pending the fuid rather than to an increase OF IFS
quantity, and engineers on both sides OF the Atau.
tic have 'indorsed the system. The Government
experiments will il is presumed, definitely settle
the question When they ere completed and pub
lshed we shall learn whether the principle OF high
or extreme expansion is to be preferred 70 me doc
rine of those who hold that the available force of
the charge can vary but little, whether compressed
into no. /, or / Of its initial volume; that ans.
bursting steam and money is much alike, gold
dollar going no further than one OF silver, nor
VARYING in value whether laid down IN one piece or
in halves quarters or dimes. There are prooa1'y
no expenditures of force unattended with loss or
waste; but by no system of saving can the princi-
pie be reversed and the outlay of one portion COM
inand return due 10 a larger portion.
To the second problem this paper is ia
tended more especially to invite attention
one of high import to the Government-since
it involves the question of speed, and that,
in vessels Of war, is vlta-is almost every
increase of few knots in our cruisers would have
virtually ended the late horrible war two or three
rears 60 saved thousands of lives and multiplied
million, of money; that il may rs vel be optalnet
IS current rates and will be, though perhaps not
without further struggling against PLAIN law OF
nhysics-plan and perfect to those who look into
L; stumbNngblock aud foolshness 10 those who
10 not, viz: those who prefer rectangular planks
to the form of blade which science prociaims
and nature everywhere confirms, whose ideas or
driving sLDs over seas ard rivers are those OF me
builders of Roman galleys and engineers OF tho
middle ages. They propelled vessels BY two, four,
and sometimes six oxen. Two were yokedto anu
travelled around a vertical shaft. and each SHAFT
carried pair Of wheels identical with those by
which they ground corn on the edge OF running
streams and in boats anchored on rapid rivers.
If there ere other examples OF non-adyancement
over the dark ages gross as this, we know ho'
where 10 look for them. Our planet Is scnooi lpT
engineers as for other professions II is alive with
illustrations OF mechanical laws, as hxed ana iui-
mutabe as the universe itself; and nothing > mors
certain than that only SO far as our devices aGcoi
with them can they succeed. Ihusit VIII peas heFe-
toforc with the propelling blades OF steamer as
with the force that propels them. Abortlve muse
be all attempts to make her speed what ought 10
be so long the principle OF tor@ so Distinctly anu
variedly manifested in organisms that move rapiuy
tbrough airand water is ignored. II Is fundamen-
taI No finite intelligence can improve or SUPER
sede IL. There is nlarvcousy more in II than
common observation perceiveS. IL governs Quiet
attributes. Endless are the projects on mnor
popts. and all of them iruitless for lack OF thae
which only can give value to any.
Every horizontal section OF blade has dImcr-
ant vel1crv and 10 make the resistance and effect
Uniform. its width must dimiaish cith t@e DIP.
The center of resistance. instead OF being near tho
extremity. will then be drawn in toward the center
of the blade and economy OF force VIII reSui'.
There is in fact, reciprocal influence pcrvadins
everv nart every feature and movement OF per-
Or tfl,i,, sud yhersver hi harmonious aeuof