The Sun.
London, England, 1847-12-27 00:00:00

LITERATURE.

A CATECHISM OF THE STEAM-ENGINE,
illustrative of the Scientific Principles upon which its
Operation depends, and the practical details of its
Structure in its Application to Mines, Mills, Steam
Navigation and Railways. By John Bourne, C.E.
Air. Bourne is already favourably known to the
public as the author of a quarto treatise on the
steam-enginP, which is confessedly the best in the
language. The present work is not intended to
supersede the larger one, but rather as an introduction
to it. The " Catechism "is eminently practical in its
character, sound in its doctrines, and embodies the
results of the author's own experience, not being, as
is the case with many other works on the steam-en-
gine, the mere untested theorising of amateur closet
engineers. The first part of the " Catechism " treats
of the mechanical principles involved in the applica-
tion of the steam-engine ; the second of strength,
constructive details, and management. The following
theory of the causes of the destructive corrosions of
marine boilers is new, and if proved to be correct, is
most invaluable :

" Q.—What is the cause of the rapid corrosion of
marine boilers ?

" A —Marine boilers are corroded externally in the
region of the steam chest by the dripping of water
from the deck; the bottom of the boiler is corroded
by the action of the bilge water, and the ash pits by
the practice of quenching the ashes with salt water.
These sources of injury, however, admit of easy re-
medy ; the top of the boiler may be preserved from
external corrosion by covering it with felt, upon which
is laid sheet lead soldered at every joint so as to be
impenetrable to water; the ash pits may be shielded
by guard plates, which are plates fitting into the ash
pits, and attached to the boiler by a few bolts, so that
when worn they may be removed, and new ones sub-
stituted, whereby any wear upon the boiler in that
part will be prevented; and there will be very little
wear upon the bottom of a boiler if it be embedded
in mastic cement laid upon a suitable platform, The
greatest part of the corrosion of a boiler, how-
ever, takes place in the inside of the steam
chest, and the origin of this corrosion is
one of the obscurest subjects in the whole range
of engineering. It cannot be from the chemi-
cal action of the salt water upon the iron, for the
flues and other parts of the boiler beneath the water
suffer very little corrosion ; and in steam-vessels
provided with Hall's condensers, which supply the
boiler with fresh water, scarcely any increased du-
rability of the boiler has been experierced. Never-
theless, marine boilers seldom last more than four or
five years, whereas land boilers made of the same
quality of iron often last eighteen or twenty years;
and it does not appear probable that land boilers
would last a very much shorter time if salt water were
used in them. The thin film of scale spread over
the parts of a marine boiler situated beneath the
water effectually protect them from corrosion ; and
when the other parts are completely worn out, the
flues generally remain so perfect, that the hammer
marks upon them are as conspicuous as at their first
formation. The operation of the steam in corroding
the interior of the boiler is most capricious—the
parts which are most rapidly worn away in one
boiler being untouched in another; and in some
cases one side of a steam chest will be very much
wasted away, while the opposite side remains
uninjured. Sometimes the iron exfoliates in
the shape of a black oxide, which comes
away in flakes like the leaves of a book; while,
in other cases, the iron appears as if eaten
away by a strong acid which had a solvent action
upon it. The application of felt to the outside of a
boiler has in several cases been found to accelerate
sensibly its internal corrosion; boilers in which there
is a large accumulation of scale appear to be more
corroded than where there is no such deposit ; and
where the funnel passes through the steam chest is
invariably much more corroded than where the funnel
does not pass through it. These facts appear to in-
dicate that the internal corrosion of marine boilers is
attributable chiefly to the existence of surcharged
steam within them, which is, steam to which an ad-
ditional ',quantity of heat has been communicated
subsequently to its generation, so that this temperature
is greater than is due to its elastic force; and on this
hypothesis the observed facts relative to corrosion be-
come easily explicable. Felt applied:to the outside of a
boiler, may accelerate its internal corrosion by keep-
ing the steam in a surcharged state, when by the dis-
persion of a part of the heat it would cease
to be in that state ; boilers in which there
is a large accumulation of scale must hare
worked with the water very salt, which
necessarily produces surcharged steam ; for the tem-
perature of steam cannot be less than that of the
water from which it was generated, and inasmuch as
the boiling point of water, under any given pressure,
rises with the saltness of the water, the temper-
ature of the steam must rise with the saltness of
the water, the pressure remaining the same ; or, in
other words, the steam must have a higher tempera.
ture than is due to its elastic force, or be in the state
of surcharged steam. The circumstance of the
chimney flue passing through the steam will ma-
nifestly surcharge the steam with heat, so that all the
circumstances which are found to accelerate corro-
sion, are, it appears, such as would also induce the
formation of surcharged steam. Besides, the natural
effect of surcharged steam is to oxidate the iron with
which it is in contact, as is illustrated by the familiar
process for making hydrogen gas by sending steam
through a' red hot tube filled with pieces of
iron ; and although the action of the sur-
charged steam in a boiler is necessarily very
much weaker than where the iron is red hot,
it manifestly must have some oxidizing effect, and the
amount of corrosion produced may be very material
where the action is perpetual. Boilers with a large
extent of heating surface, or with descending flues
circulating through the cooler water in the bottom of
the boiler before ascending the chimney, will be less
corroded internally than boilers in which a large
quantity of the heat passes away in the smoke; and
the corrosion of the boiler will be diminished if the
interior of any flue passing through the steam be
coated with fire brick, so as to prevent the transmission
of the heat in that situation. The best practice,
however, appears to consist in the transmission of the
smoke through a suitable orifice below the water
level, so as to supersede the necessity of carrying any
flue through the steam at all ; or a column of water
may be carried round the chimney, into which as
much of the feed water may be introduced as the
heat of the chimney is capable of raising to the
boiling point, as under this limitation the presence of
feed water around the chimney in the steam chest will
fail to condense the steam."

BRITISH DIPLOMACY lIV THE RIVER
PLATE.

The author of this pamphlet is evidently well ac-
quainted with his subject, and gives a clear and suc-
cinct account of the history of the quarrel between
Rosas and the French pirates (for they can be con-
sidered in no other light), who took forcible possession
of Monte Video and expelled from that city the Pre-
sident of the Oriental Republic, General Oribe. The
pamphlet shows how completely, in this as in
every other instance, Lord Aberdeen was bamboozled,
gulled, and hoodwinked by M. Guizot, and how reck-
lessly British interests were sacrificed to the main-
tenance of the entente cordiale. In fact, the incom-
petency of the late Foreign Secretary is becoming
every day so apparent, that whatever Ministerial
changes may hereafter take place, the restoration of
old Dame Aberdeen to Downing-street is impossible.

(ROMAN) CATHOLIC DIRECTORY for 1848.
From the statements contained in this annual pub-
lication, it would appear that there are in Great Bri-
tain 545 Catholic churches and chapels, ten colleges,
eleven monasteries, thirty-eight convents, and 707
missionary priests. The particulars connected with
these and other statistics are given with considerable
minuteness, and have evidently been accumulated
by a research of great; diligence. For example,
there is an alphabetical list of the grand total of 806
missionary priests resident in Great Britain, with
their private addresses. The frontispiece is a neat
engraving of the late Bishop Griffiths; and there are
besides some interesting details respecting Papal
Rome—instance the catalogue of the different car-
dinals, with their ages, and the dates of their ap-
pointment.

SHAKSPERE PROVERBS. Collected by Mary

Cowden Clarke.

Among all the variety of Shaksperian volumes it
is strange that one like this has never before (to our
knowledge) appeared. It is a little book, but a book
running over with wisdom—not the nuts of expe-
rience, but the very kernels of philosophy. Mrs.
Cowden Clarke has already shown her industry and
her familiarity with the writings of the greatest bard
God ever placed on this earth, by her elaborate and
comprehensive Concordance to Shakspere. Here she
has, as she explains (quaintly enough) on the title-
page, given us " Shakspere Proverbs, or the Wise
Saws of our Wisest ;Poet, collected into a Modern
Instance." As a specimen of how:the little book has
been compiled, we transcribe a single page :
" The shepherd seeks the sheep, and not the sheep
the shepherd."

" They do not love that do not show their love."
" To plead for love deserves more fee than hate."
" Truth hath better deeds than words to grace it."
" The current, that with gentle murmur glides,
Thou know'st, being stopp'd, impatiently doth rage."
" That man that hath a tongue, I say, is no man,
If with his tongue he cannot win a woman."
" The strongest oaths are straw
To the fire i' the blood."
" To die, is to be banished from myself,"

" 'Tis the curse in love and still approved.
When women cannot love where they're beloved."
There is one thing in the volume we must heartily