The Liverpool Standard and General Commercial Advertiser.
Liverpool, Merseyside, England, 1843-06-02 00:00:00

CORRESPONDENCE.

DOCK WAREHOUSES.

TO THE EDITOR OF THE' LIVERPOOL STANDARD,

perceive that the warehouse owners are severely
attacked in the Albion of this week; evidently by one, •cOlo,
I am sorry to say, even now, is all powerful in guiding, and
directing the dock affairs of this port.
It is melancholy to reflect, that after the battle which the
conservatives have so nobly fought and won, that one of their
most deadly enemies—a man too, of " such manners and such
morals"—should now he the real leader in that important
trust; and the consevative party ought to be warned, that if
such men are allowed to guide the dock affairs, that that
trust, which ought to be a tower of strength to them, will
only prove a source of weakness. This man hates the ware-
house owners, first, because they are almost all conser-
vatives, and, secondly, because they were the main in-
struments in destroying the radical predominance in the
Town-hall,—l wish I could add in the Dock-office. There
is some presiding genius on the latter board, which, though
neither openly seen nor heard, seems to check control and
neutralise the conservative influence. I can give no greater
proof of the truth of this remark than by stating that God's

holy dad is habitually profaned at the new dock works, the

men working on that sacred day, as though they were living
in a heathen rather than a Christian land. The first ground
of attack upon us is, that the warehouse owners have tied
down the dock committee not to erect one-third of the ware-
houses around the Albert Dock until the one part has been
in operation for two years. Now, in my judgment, the ware-
house owners have clone a wise thing in that; their fear, all
along, has been that the dock committee, not spending their
own money, would recklessly go to work, and the sequel
has shown that their fears were not groundless. It
is said the Dock Committee have spent upwards of fifty
thousand pounds in the bringing up the foundations of the
warehouses, which, if erected, cannot be insured ; they are,
therefore, driven 'to the expedient of making their ware-
houses what is called " tire proof;" there again their folly is
seen, the walls of the foundations are laid too far apart ; or-
dinary beams will not carry the width, and they are com-
pelled to go to the 'expense of beams of an unusual length,
which are of course very expensive. By the newspaper re-
port of their proceeedings, on Thursday, the 18th of May, I
observe that the warehouses are to cost £36 ss. per
square yard, which, with, the land, may be called £4O;
and, as there are five rooms including the vaults, the cost
will be £8 per square yard of superficial warehouse room;
now, the dearest warehouse in the port has never cost more
than £2 per superficial square yard, so that if the Dock
warehouses are to pay,—or in other words, if there is not to
be a tremendous loss upon them they will have to charge four
times the rate of rent now charged in the present warehouses,
i. e. threepence per bale for cotton per week. But say their
advocates we shall save in the fire insurance. Now the in-
surance would have to be £8 per cent to make up the differ-
ence between the rent now paid for cotton, (viz. one penny
per hale per week,) and the dock warehouse rate, viz. 3d. per
bale per week ; a rate, high as the premiums are at present,
which, we are sure, never will be changed.
The length, too, of the warehouses is such that the light
cannot be carried from one end to the other; and it is very
probable that gas will have to be burned all day longin them.
Another charge is, that the transit sheds, which were a boon
to the warehouse owners, are a 'failure. Every one' knows
the difference between a thing being worked by a friendly
and an unfriendly hand ; were the transit sheds fairly worked,
I know they would be more useful than they are ; but still I,
hear of many instances, in which they have been very useful,
and are found to be a saving of time to the ship owners, and
of money to the merchants : and when they are more known,
and the rules and regulations better understood, I venture
boldly to predict, that they will be found to be a great bene-
fit to the trading interests.
One word more about fires. If the-origin of the recent
fires is what it is now generally suspected to be, the dock
warehouses would be no more free from them than any
others, but the loss would be attended with the additional
aggravation of ships with the warehouses.
In conclusion, however, let me observe that I think some-
thing ought to be done by the owners of warehouses to put a
Stop to the frequency of fires. The trade of the port will be
injured if these fires go on, and if they do not make sonic
attempt to accomplish this, their property will be superseded
by a different and safer kind of warehouses

A WAREHOUSE OWNER.

TO THE EDITOR OF THE LIVERPOOL STANDARD.
London, May 31, 1843.
SlR,—Your Numbers of the sth and 16th instant respec-
tively contain statements concerning some recent experiments
made with a screw propeller, in a vessel called the " Liver-
pool Screw," constructed by Messrs. Mather, Dixon, and
Grantham, of your town, which call for somc remark, as
they would tend, if permitted, to remain unnoticed, to lead
to erroneous conclusions, not only as to what has been here-
tofore effected by other experimentalists, but as to the abso-
lute value of propellers of this description, when compared
to that of the paddle-wheel.
The invention of the screw propeller is attributed to various
persons. But the conception of the application of such an
instrument to give progress to bodies through water, can no
more be raised to the rank of a discovery than the first use
of a paddle-wheel in a steam-vessel can he considered so now.
The idea of using a screw, (under which name we must class
all propellers whose motion in the water is helical or spiral,
whatever be the form of its blades,) is of great antiquity.
The sole merit must, therefore, be derived from the mode of
applying it, and it is my object in this communication to in-
quire in what respect the Liverpool screw is superior to its
predecessors, or wherein it merits the high encomiums which
you have bestowed upon it? To the spirited gentlemen from
whom it emanates I am ready to award the credit of having
done something to advance our knowledge on this important
subject.

The screw propeller has been applied in various positions
in the vessel, namely, at the bow, before the stern, by
Brown, in 1827; one on each quarter by Captain Carpenter,
and (with much the best effect,) in the dead wood by Mr.
Smith. This last position is selected in the " Liverpool
Screw," and, although in the details of her construction, the
precise form adopted by Mr. Smith has not been followed,
yet I apprehend it will be conceded by any impartial person,
that when the propeller is placed before the rudder, and in a
space between the stern-post and the hull of the vessel, it is
virtually placed in the dead wood. The position of the pro-
peller of the " Liverpool Screw" is clearly specified by the
expression, " in the dead-wood," and if the mere change of
form given for no obvious reason, is to constitute a novelty
or an improvement, the mere application to an iron vessel,
in which there can literally be no dead-wood, would have
equally emancipated the projectors from any claim of Mr.
Smith's. In the discussions which have from time to time
arisen in our courts of law, the nature of " mechanical
equivalents" has been well defined, and the substitution of an
eccentric for a crank, or a wedge for a lever, has been held to
be a " colourable imitation." Where, therefore, instru-
ments differing so widely in form and character, were still
held to be imitations; there can be no doubt, but that sup-
posing Mr. Smith's claim to placing the propeller in the
dead-wood to have been a new discovery at the date of his
patent, any propeller placed relatively in the like position as
regards the vessel and the rudder, will be considered an in-
fringement of his patent.

But the direct motion of the engine adopted in the " Liver-
pool Screw" is claimed as a novelty. Now the direct engine
has been adopted by Smith in the Archimedes, in her first
trials, by Ericcson in the " Stockton," and by Weinshurst
in the " Novelty." These vessels had also, like the " Liver-
pool Screw," high pressure engines and short strokes,
whereby a greater number of revolutions could be obtained
on the engine shaft than with a condensing engine. The
only difference in the examples is, that the " Liverpool
Screw" has oscillating engines. But as such engines have been
applied indiscriminately to every purpose for which steam is
applicable, it surely cannot be assumed there is either merit
or novelty here, since there is no essential advantage in this
individual application ; and were the idea of using a screw and
oscillating engines valuable, their adoption in two vessels by
Penn would have anticipated these projectors on the score of
novelty.

Passing the minor question, however, of the value of an os-
cillating engine, we must enquire what are the characteristic's
which distinguish the direct motion from that of the inter-
vening apparatus of gear wheels, or other multiplying mo-
tions—what the efficacy of this method of producing a direct
action—and lastly, are the alleged defects of a multiplied ve-
locity of the screw over that of the engine a really formidable
detect?

Our experience in paddle-wheels and in the theory of the
resistance of fluids leads to the almost self-evident truth
that the greatest effect in re-action, as compared to the im-
pulsive effort, is obtained by having the plane or surface of
the impelling body at a right angle to the line of motion of
the body propelled. This is only obtainable in the paddle-
wheel when the float is vertical, and in the screw propeller
no portion thereof can ever be in this position ; it is only
possible, therefore, to approximate thereto, which is done by
making the screw as flat as possible, or, as it is technically
termed, having a short pitch. Hence it is obvious that, as
the pitch is decreased for this purpose, the velocity of the
screw axis must be proportionably increased. The rules
which must be observed to get the best mean with reference
to the difficulties on either hand are beyond the sphere of
these remarks—but suffice it to say, that in all cases the ve-
locity of the screw axis considerably exceeds that of the axis
of a condensing engine, but does not necessarily exceed that
of a high pressure one. Hence we are reduced to the di-
lemma of either using high steam or of multiplying the mo-
tion of the engine shaft, and I shall now proceed to enquire
the relative value of each system.

The condensing engine may be considered as a perfectly
safe instrument. In the vast experience we have had in this
country of every variety of vessels and engines, there is not
an instance in my recollection of the life of a single passenger
having been lost by the explosion of a well constructed low-
pressure boiler. On the other hand we have a melancholy
list of fatal catastrophes which have been caused by even
small increases of the pressure on the boiler beyond what
may be properly termed low pressure steam. With this
striking contrast in results, we cannot hesitate to designate
the man a bold one who would send a vessel on a long voy-
age with a high-pressure engine. Rather, I will say, (advo-
cate as I am of screw propulsion, and sanguine, yea! confi-
dent as I feel of its ultimate general introduction,) let us
stick to the much abused paddle wheel, which has been thu
mercilessly attacked by the writer of the articles alluded to,
but which. despite its effects, has produced those miracles in
Trans-Atlantic Steam Navigation which have added to our
country's glory. The worst that can happen to a paddle-
wheel leaves many chances of escape, but high pressure
steam, when it causes explosion, must surely be attended
with fatal consequences to many, if not all, on board, and
from which there is no possibility of escape.
The adoption of a multiplied motion by means of spur
wheels (for I have no hopes that ropes or chains can be ren-
dered durable) enables us then to use a condensing engine,
and our inquiry is next directed to the amount of drawback
entailed by the gearing. Now we have numerous instances of
such wheels having lasted upwards of 20 years, and there is
an admirable specimen in the Mint, by Rennie, of wheels
which have been in constant use for upwards of thirty years,
and which are still in good condition.
It is futile then to talk of the " well known disadvantages
of spur wheels," Machinery can never he so perfect as we
desire it, and at every arrangement comprises advantages and
disadvantages; experience and judgment enabling us to strike
the balance in favour of the most efficient. No engineer
would hesitate to guarantee constructing toothed wheels of
any conceivable strength, and I have no hesitation in saying
that with gearing judiciously constructed, we may insure a
really simple, safe, and more economical arrangement than
with either the direct high pressure engine and screw, or the
condensing engine and paddle-wheel, subjected as the latter
is to concussion and irregular resistance, from which the
screw propeller is wholly exempt.
Having, therefore, disposed of the alleged superiority of
The direct high pressure engine, I may next consider the
merits of the propeller itself. The modification now brought
forward in the " Liverpool Screw," under the name of
Woodcroft, is clearly enough described in Tredgold, in the
first edition of his Treatise on. the Steam Engine, published
in 1827, where, in a very brief notice of the theory of screw
propulsion, he calculates the effect of using a screw with an
increasing pitch. I could easily demonstrate such a modifi-
cation to be worse than valueless. I shall not, however
stop to discuss that point, but reserve any demonstration
my opinion if it is challenged.o.
The resulis in the " Liverpool Screw," (which I shall
shortly shew are vastly inferior to other examples
of the like
nature,) are, in my opinion, attributable in a great measure,
if not wholly to the peculiar form of the screw therein ado
ed
The performance of the " Liverpool Screw," is alleged
be superior to that of the paddle wheel in the proportion to
sto 4. I must say that the writer betrays great want ofeto
gineering experience in jumping to this conclusion from such
imperfect data. With vessels of the same power and dimen-