A visit to this marine exhibition, located near the Danube canal (Heustadelwasser), at the Prater, offers everyone, whether a sailor or a land rat, so much interest that we believe we must give some details.
The pavilion itself and the maritime objects which are close to the pavilion (the lantern-lighthouse with the Semaphore and the Telephone, which became so popular so quickly) are due to the munificence of the Ministry of Trade, which has devoted 42,000 florins to this exhibition.
The lighthouse consists of a small 8-sided building, whose platform, 3 toises high, is topped by a 40-foot iron lantern. It is a hollow cylinder, inside which there is a spiral metal staircase leading to the lantern, which is 8 feet high. A dioptric apparatus, consisting of 20 glass lenses, projects petroleum light from the lantern, rotating continuously at a distance of 17 nautical miles or 4 German miles.
The semaphore is an optical telegraph, with three movable wings, attached to a mast of 10 toises height and whose point is provided with a target to give signals. The mast can rotate on its axis.
It is known that all maritime nations have a common language for signals and use coloured flags and lights. The semaphore's purpose is to communicate ships at sea with the coast, and it is in communication with all the cities along the coast.
The telephone is a sort of paper clip, one and a half cubits long, made of yellow copper, resting on a trestle with a pivot, placed on the platform. It can be turned in all directions, and makes sounds so loud as to make you tremble at a distance of 15 nautical miles (3 1/2 German miles). These sounds are produced by a metal tongue, placed inside the instrument, by means of jets of steam from a machine placed in the light-house. The vibrations of the metal tongue can be modified, at will, according to whether the steam is introduced through the main pipe or through the secondary pipe.
The telephone can, therefore, play various tunes and produce different musical sounds, which is very advantageous for giving signals. The steam engine has a power of 4 horses; but it is easy to understand that at the Prater the trombone is not played with full steam. Its real purpose is to signal the reefs and rocks of the coast, in times of fog, when the lights of the lighthouse can no longer be seen.
Inside the pavilion, we notice a diving apparatus which is very complete. The air is communicated by means of a pneumatic machine, through a long rubber hose. Above this are all the oars and rowing machines.
Near the doors there is a complete collection of all the lights in use for signals and as prescribed by the International Maritime Code; on the walls are hydrographic charts of the Adriatic Sea.
©L’Exposition Universelle de Vienne 1873