Fig. 57 shows a Schumann shielded mortar (sphere-mortar,
_Kugelmorser_). In this case it will be observed that the cupola is
replaced by an enlargement of the encircling collar; and the mortar
(8.4-in. calibre) is enclosed in a sphere of cast iron, so as to close
completely the opening of the collar in any position.
Fig. 58 shows a Gruson cupola for one 4.7-in. Q.F. howitzer.
Fig. 59 shows a disappearing turret for an electric light projector.
Fig. 60 shows a Krupp transportable cupola for a 5.7-cm. gun. This is
drawn on a four-wheeled carriage, and when coming into action slides
on rollers on to a platform in the parapet. It weighs about 2-1/2 tons,
and with carriage and platform about 4 tons.
The mechanism of these cupolas is for the most part simpler than it
appears. Counterweights and hand winches are much in use for the
lighter natures of guns. The armouring of course keeps pace with
improvements in manufacture. The chilled cast iron first made popular
by the Gruson firm is now little used except for such purposes as the
collar round a cupola. Wrought iron, steel and compound plates for the
tops of cupolas have all been tried, the most recent Krupp-Gruson
designs being of nickel steel.
The sighting in some cases may be done by sights on the gun, with
suitable enlargements in the port-hole; in others by sights affixed to
the cupola itself (which of course can give horizontal direction
only); in others training and elevation are given in accordance with
the readings on electric dials, or instructions by telephone or
speaking tube. There is of course nothing unreasonable in this in the
case of indirect fire guns and howitzers, for if not firing from
cupolas they would be behind the shelter of some wood or quarry.
_Schumann's System: "Armoured Fronts."_--Lieut.-Colonel Maximilian
Schumann (1827-1889) of the Prussian engineers, who took a very
prominent part in the design and advocacy of armoured defences,
eventually produced a system which dispensed entirely with forts and
relied on the fire of protected guns. It consists of several lines of
batteries for Q.F. guns and howitzers in cupolas. He considered that
such batteries would be able to defend their own front, and the
infantry garrison was not to be called into action except in the case
of the enemy breaking through at some point of the line.
This system was actually adopted by Rumania (1889-1892) for the Sereth
Line. There are three routes by which the Russians can enter the
country across the Sereth river: through Focshani, Nemolassa and
Galatz. These three routes are barred by bridge-heads, those at
Focshani, the most important, being on the left bank of the Milkov, a
tributary of the Sereth.
The Focshani works consist of 71 batteries arranged on a semicircular
front about 12 m. long and from 8000 to 10,000 yds. in advance of the
bridges. The batteries are placed in three lines, which are about 500
yds. apart, and are subdivided into groups. The normal group consists
of 5 batteries, of which 3 are in the first line, 1 in the second, and
1 in the third. The first-line batteries each contain five small Q.F.
guns in travelling cupolas. The second-line batteries, each six small
Q.F. guns in disappearing cupolas. The third-line batteries have one
120-mm. gun in a cupola, and two 210-mm. spherical mortars with Gruson
shields. The immediate defence of the batteries consists of a glacis
planted with thorn bushes and a wire entanglement.
[Illustration: From Leithner's _Bestandige Befestigung_.