1781538572Code 8511 TacheometerCentesimal brass tacheometer, designed by Eng. A. Salmoiraghi, Milan, No. 7886, from the late 19th century.
This is a scientific instrument used in terrestrial observations to measure horizontal and vertical angles. The instrument consists of a three-spoke base with adjustment screws, a telescope, a graduated vertical circle and horizontal circle, four microscopes for reading the circles, and a double level. Dimensions: height 36 cm - 14 in, telescope length 38.5 cm- 15.3 in base width 20 cm - 7.9 in.
The Salmoiraghi company was founded in Milan in 1865 by Ignazio Porro (1801-1875) under the name Filotecnica, a school-workshop specializing in the construction of surveying instruments. Porro was a skilled builder and inventor, sometimes ahead of his time: consider his invention of the anallactic telescope, a system of lenses with variable focal length (now known as a zoom lens); or the "Porro vehicle," an arrangement of prisms for erecting images in telescopes and binoculars. After living and working in various locations, including Piedmont, Paris, and Florence, Porro settled in Milan and began teaching at the Polytechnic. There, his student was the young Angelo Salmoiraghi, and it was he who, a few years later, transformed the company into an industrial enterprise, while maintaining its initial focus on teaching. In 1871, Salmoiraghi became a partner in Porro and in 1877 purchased the factory, expanding it. By 1890, it employed approximately 150 workers and covered a surface area of 1,500 square meters. From 1906 to the beginning of the First World War, the company changed its name to Filotecnica Salmoiraghi and expanded its product range: in addition to surveying instruments, it produced mathematical, drawing, astronomy, meteorology, and navigation instruments, and its catalog included more than 300 pieces. The instruments it produced were of excellent quality and achieved numerous successes at World Fairs. During the Second World War, the company was considered a war target and its facilities were bombed, but at the end of the conflict, it quickly recovered. In the 1970s, it was purchased by Dollond & Aitchinson, along with Viganò, an optics company that had long been a competitor of Salmoiraghi. The Salmoiraghi & Viganò firm still exists today and returned to being “Italian” in 2000.
Topography studies the tools, surveying techniques, calculations, and drawings needed to graphically represent a portion of the Earth's physical surface on a map, highlighting details such as roads, rivers, buildings, and crops. Topography is one of the oldest sciences. The Egyptians measured the land along the Nile to retrace its boundaries after the river's periodic floods. The Greeks and especially the Romans already employed highly precise topographical methods; teams of surveyors (the gromatici), following the Roman legions, traced boundaries and divided conquered lands into regular plots, which were then described and represented on copper plates. Among the Arabs, topography served to construct geographical maps and to measure agricultural areas and land for cadastral purposes.
