New-York daily tribune. [volume] (New-York [N.Y.]) 1842-1866, 1855-06-12
NEW INVENTIONS.

The National IntsLigeHcer presents long communi-
cation from Mr. Thomas Ewbank addressed to The
Secretary of the Navy and inviting the attention Oh
the DEPARTING mt 10 bis proposed Improvements In the
form of paddlewhee steamers This Is the SUBJECT 10
which the came writer when Commissioner OF Patents
devoted considerable number of pages of the Patent
Office Report, illustrated by number OF engravinss'
Coming from 20 high source the matter has been re-
printed in foreign journals OF the highest reputation
and has sttracr ed al unusual degree Of attention.
Commencing with several paragraphs on the pro-
crsss of the age and on the influence of form on many
portions of both artificial and natural mechanism, Mr.
Fwbank proceeds TO state that paddle blades should
be long, narrow tapered and pointed
Were these he remarks, tapered and arranged TO 90
into the water endwse and close to the vessels SIDE
with the pointed ends downward, they would APP
proach in some degree the true figure end disposition,
and AZ che reduction of thickness of natural blades out
ward is permanent feature under ell circumstances
the same trait should be exhibited in artificial propel-
lors To whatever extent the fluid medium is displaced
in the line Of the blades action by their solid contents,
room for them 10 act in and fluid TO act on Is dimn-
shed. Taking the mean thickness and number OF the
massive panks that constitute the blades OF ocean
steamers they lose from this cause from eight to ten
feet Of stroke in every turn of each wheel Assuming
two hundred and fifty thousand revolutions "a the
average number in trip the Atlantic, over nve
hundred miles 81 stroke thus lost IN each wheel,
and eleven hundred in both or in other words between
twenty and thirty thousand pounds of timber are
wbirled eleven hundred miles through air and water,
and TO no purpose but consuming power and wearing
| out the motive machinery.
A correct form, he continues, would remove the EVIL
which now attends dminuton ofthe number ofblades.
Instead of prop cling surface extending from twelve
TO fifteen feet from vessel side, being brought 10
sudden conflict with n wave, mere point OF the blade
would be presented TO it. Instead OF attempting
to arrest the SWELL and be shaken or carried away
by it. il would 90 softly and silently into and through
IT, and come out without lifting tuns OF water with It,
Recognizing briefly the fact that much propelling
surface is desirable and assuring that the propose
blades are not subject to the strains which the present
wheels UNDERGO from a vessel rolling, Mr.. Ewbank
contends that another property Indispensable to a
propeer il that The center of resistance is in the CEN
ter OF the blade not ut ts extremity Ia the present
blades the strain is collected the further point from
the shaft. while in the proposed blades a section near
the point does Just as much and only much work AS
an equal section through the wdest part, extended
sweep compeneatng for diminished surface. BY this
principle the resistance is in effect spread equally over
tie whole face of the blade, las in the wings OF bird
or propeller of a fish, aud the center OF resistance
| brought near TO the axle.
Aside fiom a few concluding remarks the
proueller We have given in the order aad genes
aly in the authors own words the prominent points
OF the article alluded to. They appear to be the same
as those set forth in the Patent0ce Report for lst9
and rot being able to agree with the views of Mr..
Ewbark, We will briefly state our objections to his
theory
The revolution Of the shafts Of a side wheel steamer
invariably produces three effects only Of which ia
useful; and it becomes important increase this
by diminisl ing the other two. The wheels churn
ogitae the water by the punging and lifting OF their
floats; they drive the water continually backward by
their direct pressure in that direction and then mpe
the vessel forward by the reaction thus induced. Ony
the last effect is useful and in the FIST starting of
heavy steamer from state of little else is effected
than the chu,ning and forcing backward of the water
As tie vessel gathers way the power lost in the latter
is diminished but the churnDg still remains and must
! from Tie nature of the
The motion of the water backward generally recog
nized by engineers the slip" Of the wheels is
decreased by charging the area o. the paddles. In
otl er words it is desirable to get firm hold of the
water by grasping as large a quantity as possible
But the paddles or floats do the water exactly
edgewise, Except in some Of the paten FORMS, and
their position in plungiug and rising becomes more
incl1 ed tbc Gtep,r the wheel is immersed. As in
creasng tic dip" Of the wheels would thus increase
the obiectiorabc channg effect, known to engineers
as the "loss by oblque action, we are compelled to
increase the area of the paddles in the other direction
and the proper theoretical paddle thus becomes very
broad blade dipping very slightly beneath the
surface.
! Iiehtness and economy demand that these paddles,
If not the frame that carries them shall be o. wood
and strength demands that these wooden planks shall
be of considerable thickness. To dip and lift thick
plank even perpendicuarly in water consumes some
power and this induces TIE employment of as small
number as possible, but desire TO divide the
sioIs and also TO leave water Enacted between
the floats tends TO the opposite extreme and the result
is a compromise; the number OF paddles immersed,
varying from two to twenty according To the nature Of
the circumstances or the skill of the designer. View
ing an ann of the wheel when in action, the upper
extremity or center of the wheel moves of course
steadily forward, while the lower extremity as we have
already seen, is slipping less backward in It's
| paving action on the water Somewhere between
these is pon; at rest and the position of this point
limits tie extreme breadth Light OF the float. As
this portion has 10 motion any quantity Of surface
there would be OF no avail in propelng, and any
above that point would be positive intolerance by
acting on the water in wrong direction II is evil
dent from this consideration alone e. at the arms should
be slender may be, and it practically posi-
be TO make each arm like the wing of bird it would
rot be desirable TO do Art not nature, has taught
US TO construct WHEELS and art has enabled us by the
| az spco .f 10