ON RIFLED GUNS FOR ATTACKING ARMOUR-PLATE DEFENCES. 103 
From the various observations the following are the results :—The obser-= 
vations made on the Humber comprised 55 tides: the greatest variation at 
spring tides was 22 feet 3 inches flow; and the least variation at neap tides 
a rise only of 10 feet 7 inches. The lowest level of low water at spring tides 
was 3 feet 8 inches, and the highest rise 27 feet 11 inches; the highest at 
low water of neap tides 11 feet 2inches. The mean rise of the 55 tides above 
low water was found to be 16:95 feet. The average time of rising tide is 
about 54 hours, and the falling tide about 63 hours. 
At the season of the year when the observations were taken it is generally 
calm, and there is no undue influence exerted on the rise and fall of the tides 
on the Humber ; but at the time of the equinox, and in stormy winter seasons, 
particularly during north-westerly gales, there is a much greater rise and fall 
during spring tides than would otherwise occur. 
The observations made at Goole (which port is about 30 miles above Hull) 
show on the 63 tides a mean rise of 11-67 feet,—the greatest rise above low 
water being 15 feet 4 inches, and the least rise from low-water line 7 feet 
7 inches. 
The tides at Goole average about 3 hours in rising, and a little over 9 hours 
in falling. 
The mean rate of the tidal wave on the Humber is from 24 to 3 miles at 
neap tides, and 4 to 5 miles per hour at spring tides. 
On Rifled Guns and Projectiles adapted for Attacking Armour-plate 
Defences. By T. Aston, M.A., Barrister at Law. 
[A communication ordered to be printed among the Reports. ] 
As it is now an admitted fact that naval warfare will be carried on by iron- 
clad navies, it has become an imperative necessity that the navy of England 
shall henceforth be armed with artillery adapted for attacking the new 
armour-plate defences which all nations are hastening to adopt. The supe- 
riority which defence so suddenly acquired over attack, by simply putting 
on a coat of armour, threatened to upset not only the theoretical but the 
practical tactics of modern warfare. The necessity of improving the means 
of attack so as to restore, as far as possible, the disturbed equilibrium was 
obvious to every one; and the contest which has been carried on in this 
country for the last two or three years between the attack of improved artil- 
lery and the defence of improved armour-plates has been watched by all of 
us with the greatest interest. From a scientific point of view, with which 
we are on this occasion more immediately concerned, the subject was one 
which engaged the attention of some of the keenest and most experienced 
intellects of the country,—these, on the one hand, giving practical aid on the 
side of defence, those, on the other, devoting their best energies to restore 
attack to what must be considered its normal position of superiority. For a 
long time—for too long a time—the defence-people had much the best of it. 
Under the energetic superintendence of the Plate Committee (who in this 
matter de repuvlica bene meriti sunt), armour-plate targets were erected by 
our able engineers which at fighting-ranges laughed to scorn the utmost 
efforts of the artillery attack brought against them. Some of the targets 
combined the resistance of iron with wood ; others, constructed-with far-seeing 
