Other denominations
il widna [The Ear]
Original use
Military/sound mirror
Current use
Military/sound mirror
Engineers
Royal Engineers (British Military Heritage)
Concrete by reinforcement
Concrete is a relatively brittle material that is strong in compression but less so in tension.
To increase its overall strength, steel rods, wires, mesh or cables may be embedded in concrete before it sets. This reinforcement, often known as rebar, resists tensile forces. By forming a strong bond, the two materials are able to resist a variety of applied forces, effectively acting as a single structural element .
Construction method
In this case, the concrete can be made by mixing the components directly on site, or it may be transported from a production plant in concrete-mixer trucks.
This method has the disadvantage of leaving the concrete exposed to the elements while it is setting. Whereas, with other methods, the environmental conditions can be controlled during setting, providing greater control over the outcome, with cast-in-place concrete a series of tests and protocols are necessary to verify its final strength.
Architectural concrete
- textured walls
- wooden formwork finish
- stamped concrete
- exposed aggregate concrete, colored concrete, etc.
Structural types
State of Conservation
Description
This curious element, which may seem set in the landscape in a puzzling way, serves a very specific purpose. It is a defensive element designed to amplify the sound waves made by airplanes approaching the island, in order to anticipate possible air attacks.
The construction of this type of defense infrastructure was promoted by the British Empire in the 1930s to protect its overseas colonies. Later, the Second World War made them necessary in the south of England. While a number of sound mirrors of different shapes and sizes are still standing on the British coast, the one in Malta is the only one left in the entire Mediterranean basin.
The position and shape of these elements was calculated following careful study, which took into account the expected direction and height of the attacks, as well as any nearby elements, natural or man-made, that had to be avoided or that could cause interferences or reverberations. Optimization of the element’s placement and design, and the use of the most efficient electronic equipment, would help increase the possible reaction time toward mounting a defense.
The sound mirror in Malta, finished in 1935, is a very long vertical concrete wall with a double curvature and a series of buttresses at the back to improve its stability. Its design was based on another sound mirror built a few years earlier in Denge, in the county of Kent, England.
The initial tests showed an average listening distance of about 25 miles (the human ear alone reaches less than five), but its effectiveness was called into question after numerous confusions and failures in the detection of attacks. Eventually, sound mirrors became obsolete, replaced by other more precise technologies, including radar.
Malta
WCJV+9C Triq it-Targa, In-Naxxar
Commission
1934
Completion
1935
Links