LAND AND WATER 
January 23, 1915. 
EXPLOSIVES. 
To th« Editor of Land and Water. 
Sib —Mr Jane'a statement " that Germany is ahead of 
(he rest'of the world in the matter of high explosives seema 
to be well founded (at least, bo far as Tfe are concerned), and 
to constitute the explanation of several apparently isolated 
facts. I venture to put forward some suggestions and to ast 
Bome questions. , _ , 
(1) Is tbis not probably the explanaUon of the effect 
produced by the German siege guns and Jack Johnsons t The 
debated question of the size of these guns is not the impor- 
tant onei but the explosive. We hear nothing of such 
devastating effects being produced by our shells. 
(2) The pictures recently published of the ruined forts 
at Tfiinetau suggest that the Japanese possess an equally 
powerful explosive. The fall of Tsingtau seems to have sur- 
prised the Germans as much as that of Namur did ourselves. 
Further a rumour declares that the Japanese have reported 
our torpedoes to be of no use, that is (I take it), compara. 
tively speaking. Could we not get some aid from our ally ( 
(3) Does this throw any light on the comparative rapidity 
with which the Good Hope and Monmouth were destroyed once 
the German armed cruisers got the upper hand ] The Good 
Hope blew up a little more than an hour after firing began, 
and the Monmouth sank within a little more than two hours. 
On the face of it the odds did not seem to be so hugely against 
MB. The battle at the Falkland Islands was of much longer 
duration. 
(4) What effect may this superiority in explosive shells 
and torpedoes be likely to have on the great naval battle which 
will take place when the German Fleet has completed equip- 
ment, trained the reservists and new recruits, and effected a 
sufficient attrition of the British Fleet by mines and sub- 
marines 1 If it does'. It is rather melancholy that after the 
experience of the Boer war we should have allowed ourselves 
to be caught again with an inferior armament and one which 
affects everything — shells, torpedoes, bombs, mines, and hand 
grenades. .What are our chemists doing? — Yours, 
H. J. C. Geieeson. 
Imagine a ship to be constructed with an absolutely 
air-tight deck, and every part of the exterior of the ship 
below the deck also of air-tight construction. Assume 
further that the bottom of the ship is 30 feet below top- 
water level, and that the whole of the space below the deck 
is filled with compressed air at a pressure equal to the external 
head of water — in fact, under the same conditions as the 
caisson bell before referred to. If such a ship be punctured 
or breached may I not reasonably conclude that she will fill 
with water until the top of the breach is well covered 1 This 
filling with water will decrease the difference in weight 
between the water displaced by the ship and the weight of 
the ship, and if to such a degree that tlie balance of buoyancy 
is lost the ship sinks. 
Now if my conclusions with regard to the ship are 
correct then I think answers to the following questions are 
required before the practical utility of compressed air as a 
means for keeping a vessel afloat after submarine attack can 
be demonstrated : — 
I. — Is it practicable for the space below an air-tight 
deck to be filled and maintained with compressed air at a 
pressure of, say, 15 lbs. per square inch without lessening 
the fighting power of the ship or the crew to an appreciable 
extent? 
II. In the event of submarine attack would the ex- 
plosion so damage the ship as to render the deck and the 
exterior of the ship below the deck and above the highest 
point of the breach no longer air-tight? 
III. — Is the highest part of the breach caused by sub- 
marine attack at such a level that, under all conditions, 
sufficient space is left between the highest part of the breach 
and the air-tight deck to preserve the balance of buoyancy. 
—Yours faithfully, John Chadwick. 
THE LOSS OF THE "FORMIDABLE." 
To the Editor of Land and Water. 
SiE, — I have been deeply interested in reading Colonel 
Maude's description of his idea for keeping fighting vessels 
afloat aft^r submarine attack. 
The reference to the " diving bell," which under the new 
name of a caisson bell is now of such, practical utility in 
civil engineering works, very happily illustrates Colonel 
Maude's suggestion for lessening the dangers attendant on 
naval wai-fare. 
There is, however, this difference between the diving 
bell and the warship. The diving bell rests on the ground 
at the bottom of the water, the weight of its structure being 
greater than the weight of the water which it displaces. 
The filling of a space in a warship with compressed air is 
intended to prevent it reaching the bottom — in fact, to main- 
tain it at the surface. If the bottom of a caisson bell is, 
say, 30 feet below top water level, it will be necessary in 
order to prevent water entering the bottom, of the bell to 
charge the bell with compressed air and maintain it at a 
pressure per square inch equal to the weight of a column 
of water 30 feet high and 1 inch, square in section. The 
pressure of the air inside will then balance the external pres- 
sure of the water at the bottom of the bell. 
Now, supposing when in this condition the bell is punc- 
tured — say, at a vertical height of 4 feet from the bottom — ■ 
the balance in pressure between the air inside and the water 
outside is broken ; for at the point of puncture the head of 
water is reduced to 26 feet, whilst the pressure of the internal 
air at this level is still equal to a column of water having a 
head of 30 feet. Air will now escape through the puncture 
and water will rise in the bell until it reaches and covers 
the orifice. The remaining air will then be locked in the 
upper part of the bell, and water will cease to enter. If 
the bell had been constructed with a watertight bottom, and 
instead of being punctured it had ripped open — say, from 
the bottom to a vertical height of 4 feet from the bottom, 
the result would have been the same. 
With considerable diffidence I would like to compare the 
punctured bell with the punctured ship, but wish it to be 
quite understood that I make no pretence to a knowledge 
of marine engineering, and if my comparisons are at fault 
I welcome corrections. 
1 believe that a ship floats because the weight of water 
wliich it displaces is less than the weight of the ship itself, 
and that when a ship fills with water to such an extent that 
this difference in weight ceases to exist the balance of 
buoyancy is lost and the ship sinks. 
OILSKINS AND RUBBER BOOTS. 
To the Editor of Land and Water. 
Deab Sib, — The response to the appeal wliich I made 
for oilskins and " gum " boots through the medium of 
your paper, has been most generous, but further efforts are 
needed to collect the large number (4,000) asked for by the 
Commandant of No. 1 Base (France). The receiving Depot is 
at 8, Beauohamp Place, Drompton Road, S.W., where all gifts 
are gladly acknowledged. Letters may be addressed to Mrs. 
Bruce Williams, 22, Alexander Square, S.W.— I am. Sir, 
yours faithfully, M. A. Williams. 
22, Alexander Square, S.W., 
Burke's Peerage (1915 edition), published by Messrs. Harrison & Sena 
(Bookselling Dept.), 45, Pall Mall, London, is now to hand. This 
valuable work of reference should be in every library. 
As evidence of the fact that "Burke" is corrected efficiently and 
right up to date we notice that the following items appear in the text of 
the work : 
The death pf Sir John Barker, December 16th, 1914 ; 
The death of Sir H. F. Grey, December 17th, 1914 ; 
and the Addenda brings the happenings up to December 19th. 
Mention is also made in the text of the honours given by the King in 
France, i.e., The Order of Merit to General Sir John French, The Garter 
to the King of Belgians, The Bath to General Joffre, and The St. Michael 
St. George to other French Generals, and all the D.S.O.B and V.C.8 
conferred up to December 19th. 
The deaths of tliree Baronets who had long been lost Sight of are 
also now recorded, ie., Sir Henry Burnaby, 5th Bart. ; Sir Richard H. K. 
Farmer, 5th Bart. ; and Sir George Compton Reade, 9th Bart. 
The price of the volume is £2 28. net. 
LOOKING BACKWARDS. 
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on " The War by Land and Water " will doubtless 
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of articles by HILAIRE BELLOC and FRED T. JANE. 
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