THE ROYAL ARTILLERY INSTITUTION. 
7 
simply hides the interior of the work, is preferable to a mantlet. An early 
and interesting instance of the employment of this expedient will be found in 
the history of the defence of Gibraltar in 1782. 
12. Admiral Sir G. E. Sartorious has submitted to the Committee a 
number of mantlets on what he terms the jalousie principle. They consist of 
plates of iron 3 ins. wide, and of any convenient length. The specimens 
produced have varied from 18 ins. to 30 ins. in length, and from -^-th to J in. 
in thickness. These plates are riveted to raw hide, or connected with iron 
hinges at intervals, but so as to overlap each other, and have been tried in rolled 
steel and homogeneous iron. One defect was common to the whole of them; 
some of the bullets or splinters of bullets invariably passed through the 
joints, notwithstanding the overlap ; the iron hinges also gave way very soon, 
as did the narrow leather thongs or strips of hide, permitting the plates to 
separate; but this defect was not observed when they were riveted to entire 
hides. 
The following is an abstract of the experiments :— 
Thickness 
of Plates. 
Material. 
Result. 
inch. 
T2 
1 
1 0 
Homogeneous iron, riveted to cow¬ 
Plates pierCed at 50 yds. 
hide ; 5 lbs. 9 oz. to square foot. 
Ditto; 5 lbs. 9 oz. to square foot. 
Plates pierced at 50 yds. 
h 
Rolled steel, ditto; 6 lbs. 15 oz. to 
Proof at 50 yds.; one bullet 
square foot. 
penetrated at 25 yds. 
i 
Homogeneous iron, hinged with iron 
The hinges gave way, but the 
mantlet was bullet proof at 10 
straps; 6lbs. to square foot. These 
plates were curved to the ogee form. 
yards. 
i 
Homogeneous iron, hinged with iron 
Not proof at 75 yards. The 
8 
strap, curved as above; 7lbs. 10oz. to 
hinges gave way after twenty 
square foot. 
rounds. 
g 
Homogeneous iron, riveted to two 
Not proof at 75 yds. 
i 
strips of cowhide; weight 5lbs. lOoz. to 
square foot; four plates ogee; 5 plain. 
Rolled steel, riveted on cowhide; 
Bullet-proof at 10 yds. 
weight 12 lbs. 2 oz. per square foot. 
The Committee reported on 2nd February 1861, Eeport No. 1412, that, 
in their opinion, the jalousie construction is unsuitable. There is a great 
liability, however the plates are attached, for the bullets to force themselves 
through at the junctions; if they are attached to jointed iron straps, these 
get broken after a few blows ; if to hide, its tendency to stretch in wet 
weather or continued damp gradually opens the joints; and their rigidity at 
other times deprives the structure of any special advantage arising from the 
nominal flexibility of this species of construction. 
13. At the suggestion of the Inspector-General of Fortifications, a trial 
was given to a screen of l^-in. wire rope in two thicknesses, disposed so as 
to cross each other at right angles; each rope was composed of 6 strands, 
each of six galvanized iron wire of about 0 055 in. in diameter. It was very 
heavy, namely 25 lbs. to the square foot, and was penetrated readily at 50 
yds., several ropes being cut asunder. Samples of a strong wire network 
