The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1856-11-20

SCREWS AND SIDE WHEELs.-The appearance in
this port of so many large and beautiful steam
ships propelled by the screw, has led the public
mind to consider the comparative value Of this
kind of propulsion with that Of side wheels. In
Great Britain the former mode is decidedly the
favorite one, and the specimens they have been
sending to the ports Of Quebec, New York and
Philadelphia are certainly an honor to its ship
and engine builders To graceful forms they add
compact and powerful engines and handsome
rig In this country we have not yet made much
progress with the screw. Our ocean vessels built
on this principle have not hitherto been very sue
cessful; on the lakes they have worked to greater
advantage.
The introduction of the screw was of first warm
ly opposed by scientific men. The idea of work
ing wheel, or an oar, or revolving blade en-
trely under water, was considered illusory. The
resistance Of the water to the submerged screw
as the vessel moved forward and the resistance
Of the back water accumulated and dragged be-
tween the screw and the stern Of the vessel, were
thought TO be almost equal to the force Of the
screw revolving against the water behind IL. The
propelling power was considered to be nearly
neutralzed by this resistance, while the side
wheel, half in air and half in water. revolved
without those practical difficulties. For a tim
the principle Of screws was left in doubt. but lat
,erly II has iriumphed over every objection. By
a skilful adjustment of its pitch, careful modif-
cation Of the form and size OF the blades and the
shaping Of the stern TO which the screw is attach
al. naval engineers have arrived at very great
accuracy in their calculations, and pretty certain
results In the construction Of their screw en-
gines.
But there arc other advantages enjoyed by pro-
pellets, which cannot be obtained by the side
wheel steamers First, in the comparative cheap
ness of their construction. Second in the unn-
ierrupiedncss and regularity Of the action Of the
screw. not attainable by The side wheel In rough
weather. Third, in the ability to carry all SAIL
and embrace the full advantages Of canvass,
whether going before the wind or with the wind
abeam. This the side wheel steamer cannot do
Fourth, in facing head wind, as propeller Of
fers but little comparative RESISTANCE. A side
wheel steamer offers with her wheel houses and
upper Nolks, utnll uoubi' 'iat VI uhHsVefte
section Of her hull to the water lne.s
We have an illustration Of this in the last trip
Of the steamship City Of Washington, from Liver
pool to philadelphia. She left port Nov 8, at
l2:37, and at midnight passed Holyhead. Nov.
6. at noon, bad made 265 miles the wind south
Mt 1lA0 all sails set. Nov. 4 wind S. TO s. r.
light, all square sails set. Nov. g. wind s. S. E.,
W. moderate, part studding sails set. Nov. o,
wind s. s. L. moderate, all sail set. Nov. 10.
wind s. to S. E. moderate, all possible sail Nov
IL, wind s. $. r fresh, all plain sail get. Nov.
IL, wind s. T. light head winds, no calls set
(Run from the previous noon, 2s9 miIes) Nov.
Is, wind variable, no sails; run $50 miles Nov.
IA, wind n. w., no sails; steaming only 2ls
miles Nov Is, wind variable, heavy head sea.
all sail set in the morning, gale coming on.
double reefed topsails; run 2js miles. Nov. 16.
wind N. T. TO w., strong gale, in all square sails
and fore and aft canvass; run $50 miles. Nov.
~, wind W.. strong winds with heavy head sea