The Liverpool Standard and General Commercial Advertiser.
Liverpool, Merseyside, England, 1844-03-19 00:00:00

THE POLYTECHNIC SOCIETY.

The monthly meeting of this society took place on
Tuesday evening last, at the Royal Institution, and was
rather numerously attended. Mr. JOHN GRANTHAM,
the President, in the chair.

RESISTANCE TO BODIES MOVING THROUGH WATER.

Mr. HENRY BOOTH (a gentleman well known from his
great improvements for the more rapid generation of
steam in locomotive engines, &c., and who had previously
published some observations on the propulsion of vessels)
read an interesting paper on " Further experiments on
the resistance to bodies moving through water at different
velocities; with some observations on the prospects of
steam navigation." He commenced by alluding to the
experiments he had formerly made, and the results of
which he had published in a small tract in 1842, on the
resistance to bodies moving through water; and stated
that he had since had the valuable assistance of Mr.
Alfred King, of the Gas Works, in trying further experi-
ments by improved and more accurate means, by which
they had arrived at more definite and satisfactory conclu-
sions. They had employed two small boats—one (as we
understood him) full in build, and the other narrow, and
sharp at the extremities, which were drawn along on a
sheet of water, by means of a weight descending by a cord
over pulleys so arranged as to remove the objections en.
tertained to that species of test. The fall of the weight
was in all the trials 13 feet, and the length of " voyage "
the same. He detailed the particulars of several experi-
ments thus carefully made, givir's minutely the respective
times occupied in each in seconds and fractions; and the
general result was, that to increase the motion of a well-
constructed vessel from a given and comparatively slow
motion, something a little more than four times the power
was required to double the velocity. He came to the
conclusion on this part of his subject, that it would be
sufficient to assume. for all practical purposes, that four
times the power was required. The lecturer then entered
into a consideration of our position as regarded steam
navigation during the last seven years, and our prospects
for the seven years to come. Much, he contended, might
be done to redeem the losses hitherto sustained by im-
proved scientific appliances. The Atlantic had certainly
been crossed in ten days, but it certainly ought to be done
in less time, especially if the object (a most valuable one)
were confined mainly to the conveyance of the mail bags,
which he thought might be accomplished in a week.
What was to be done might be stated to be the cutting of
a canal or trough across the ocean, through which the ship
would hold her way with the least possible resistance.
Hitherto very large vessels had gem rally been employed,
those running to Halifax and Bostor. baying 36 feet of
beam, and 15 or 16 feet of depth in the water. Now, he
believed that if vessels of the same length had only 22 feet
of beam, and.with an increase in depth, they would cut
their way along with much less resistance, and their speed
would consequently be much increased with the same
power. He did not see why a steamer of, say 1,000 tons,
so constructed, would not accomplish the voyage as safely
as one of double that tonnage, for sailing vessels of much
smaller size performed long foreign voyages with as much
ease and speed as those of much more burthen. The
perfection of a sailing ship was not, however, to be con-
sidered as suitable for steamers. All that was required
in the latter was so to construct then), that the trough
through which they should pass should be reduced in
transverse area, or, in other words, as narrow and as deep
only as was consistent with their safety. This was to be
accomplished by lengthening the vessel without adding to
her beam. It might be said that she would thus be ren-
dered more crank, which would certainly be the case to a
certain extent; but this objection would be (as we under-
stood him) almost wholly, if not entirely, obviated by the
employment of the screw as a propeller in place of the
paddle-wheel, which last required the vessel to be kept in
nearly an upright position. Increasing the cross-sectional
area of the steam-vessel, increased the resistance to
her forward progress ; and the narrower the angle formed
by the canal to receive her, the sharper would she
cut through it. He suggested that if a steamer were built
250 feet long and 20 feet broad only, the resistance would
be greatly decreased as compared with the present class
of vessels. They might, he repeated, double the length,
without increasing the breadth or depth ; and they might
also in such case double the power, and by these means
acquire a vastly increased speed. In support of his views
he quoted the able experiments made by Colonel Beaufort
in 1798-9. Although the body to be moved were three
times the length, the tractive, or resistive, power was
found to be only double. Experiments had also been made
with planks (in edge,) and it was found that the resistance
was not two-fold, when they were increased to three times
the length. Vessels, he believed, might be constructed of
iron of sufficient strength, and with all the adaptations he
contemplated. He also alluded to the great speed attained
by the long narrow iron canal boats (on the Androssan
principle,) which he had seen on the Preston and Lancas-
ter canal, and which travelled at the rate of nine miles an
hour. It was found with these, indeed, that the horses
drew them more easily at that speed than rt six or seven
miles an hour. II e concluded therefore, that narrow and
sharp steamers would accomplish all that could be desired ;

that vessels of 1,000 tons were sufficiently large ; and ap-
pealed to the meeting what an advantage it would be, if
the mails could be regularly conveyed be..ween Europe and
America in the short space of a week. The lecturer was
listened to with great attention, and sat down amidst con-
siderable applause.
An animated discussion ensued, in which the chairman,
Mr. Adie, Mr. Steele, Mr. King, and other gentlemen
took part, and in which the peculiar and approved moods
of ships, with reference to their sailing qualities, and the
rather conflicting opinions of distinguished individuals
who had long studied the subject, were referred to. It
was admitted that, as an abstract question, narrow sharp
vessels which required less displacement than fuller and
broader ships, would meet with less resistance, and con-
sequently sail faster, or be more rapidly propelled by
steam on a smooth sea; but some of the speakers con-
tended that in ocean storms, which had more or less to
aaciscoidiennsttatioicetdh easmaao.
be encountered on transatlantic voyages, considerable
beam and bearings aloft were required, to give sufficient
and safe buoyancy in a heavy sea-way, and to enable the
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rineattlizievv;ernpotoolfwatln
example of the necosiity. of a certain proportion of beam.
QA Q,.
She was originally 225 long ant, Wen,.
well with a head wind—in that respect beating I her
competitors. But with a beam wind and sea, she was so
chi
crank, that it was found necessary to sponson her out four
ship
etroy.
feet on each side ; and she now not only stood better to
her canvass, but steamed as fast, excepting in going head
to a gale. We forbear giving all the arguments and sug-
gestions M
adduced, that rendered o .1 . r Booth's views ques-
nly a sketch of the opinions
tionable, as we can supply
t nd he will publish his re-
marks, when we shall return he expressed. But we un dertsa
to
the subject, which is one
of paramount importance to all parties interested in the
progress of steam navigation.