1662220024Code 678 TheodoliteAntique theodolite of burnished brass signed Ing. Salmoiraghi Milano No. 3787 made in the second half of the 19th century, complete with original oak box complete.
This instrument was used in terrestrial observations for the measurement of horizontal and vertical angles and also used in the measurement of magnetic and geographical distances and azimuths.
It consists of a base, a telescope, two graduated circles, one horizontal and one vertical, small microscopes for reading the circles and double nonius for the centesimal reading of both the horizontal and vertical circles, leveling adjustment screws, double levels with water.
Measure instrument cm 27x26 h 43- inches 10.6x10.3 h 18.5.
Box size cm 30x24,5x47 - inches 11.8x9.7x18.5,
Very good condition, fully functional.
Topography studies instruments, surveying techniques, calculus and plans to represent graphically in scale a part of the Earth surface on a map, indicating its details like streets, rivers, buildings, cultivations… Topography is one of the most antique science. Egyptians measured lands along the Nile for tracing borders after periodic overflows of the river. Greeks and Romans used some topographical method very precise; some topographers teams (“gromatici”) following Roman legions traced borders and divided conquered lands in regular plots, then described and represented on copper plates. Arabs used topography to realize maps and to measure agrarian surfaces and lands for cadastral use.
After having stayed and worked in different locations, in Piedmont, in Paris and Florence, Ignazio Porro (1801-1875), well-known scientist, professor of optics, inventor and precursor in the field of wide-angle lenses, settled in Milan and began teaching at Polytechnic. In Milan in 1865 he also founded a school-workshop specialized in the construction of topographic instruments together with Alessandro Duroni, pioneer of Italian photography, with the name of Filotecnica. On the death of Duroni, in 1871, Angelo Salmoiraghi, a pupil of Porro, already a very young soldier during the third war of independence against the Austrians, entered into society with his master and in 1877, after the Porro's death he bought the factory, which took the name of La Filotecnica Ing. A. Salmoiraghi, expanding its product range, producing mathematical instruments for drawing, astronomy, meteorology and navigation; the company builds, among other things, the first Italian sewing machine. During the First World War, it supplied war instruments, mainly aeronautics, and created a camera for aerial photography. In 1927 the company took the name of La Filotecnica Ing. A. Salmoiraghi S.A.. In 1939 Angelo Salmoiraghi died. During the Second World War a large part of the production was dedicated to war equipment and the company was therefore considered a war target: the factories are bombed, but at the end of the conflict the company manages to recover immediately. In the '70s it was bought by Dollond & Aitchinson, together with the firm Viganò, and became the Salmoiraghi Viganò, which in 2017 became the property of Leonardo Del Vecchio's Luxottica.
