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The Things of Warsaw / Room of Warsaw Clocks

Zegar słoneczny w typie kompasu walcowego, MHW 28245

Cylindrical sundial

The sun, according to different hours of the same day, or according to different days of the year, reaches a different height; and this is the principle of this compass, which measures the height of the sun with the shade cast by the gnomon to show the hour that corresponds to that height. This quotation from the manual attached to the cylindrical compass provides a brief description of its working principle. The dial consists in a diagram composed of divisions: the vertical one for hours, and the horizontal one for months and days of a year. Imposed on a grid, the curves delineated on the basis of the position of the sun at different times of day and year offer the possibility to determine the time. In order to read it appropriately, it is necessary to rotate the gnomon located at the top of the cylinder to the current day of the month, and then set its front to the sun. The cast shadow will indicate the time. Even though the description may seem complicated, only a bit of practice and good weather are needed for the small sundial to become a useful timepiece. However, one needs to remember that time measurement is correct only at the latitude for which the diagram had been prepared. In this case, it is the location of the Astronomic Observatory in Warsaw (52o13’4,6”N) and the distance of up to half degree, i.e. approximately fifty-five kilometres from that parallel.

The diagram was prepared by Jan Baranowski (1800–1879), an astronomer who in the years 1825-1869 worked at the Astronomic Observatory in Warsaw, located in the Botanic Garden on Ujazdowskie Avenues. It was there that Baranowski created a diagram
that indicated on a time chart the height of the sun in Warsaw for each day of the calendar year. Jan Baranowski was the director of the Observatory; since 1862 he also lectured at the Warszawska Szkoła Główna (Warsaw Main School)– the cradle of Polish Positivism, an intellectual and social movement that emerged after the fall of the January Uprising. Clocks were mass produced in Warsaw by the Optical Institute of Jakub Pik (1845–1886), which was renowned for precision and professionalism. The Warsaw-based optician and mechanic enjoyed the status of a zealous patriot as well as lover and propagator of inventions. The sundial of his production is light – weighing mere eighty-two grams – and has a gnomon that can be folded and hidden in the cylinder, as well as a manual in Polish and a box that protects all elements. Owing to those practical solutions, it was used in the provinces of the Kingdom of Poland until the end of the 19th century. It was still cheaper than the ever more popular mechanical clocks, and it could be more precise, despite the fact that it depended heavily on the weather conditions.

Cylindrical sundial
WARSAW; DIAGRAM (1837–1844), MADE AFTER 1845
MHW 28245/A–C
CLOCK: 12,7 × 3,1 CM
MANUAL: 19,2 × 24,2 CM
BOX: 13,2 × 3,9 CM

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