Immagini

DESCRIPTION

Exhibit 600 is the Silbermann heliostat presented in 1843 to the Academy of Science of Paris. It is an instrument that reflects the sunlight in a fixed direction to facilitate experiments that require constant illumination such as spectroscopy or the use of a microscope. This device contains a mirror that guided by a clock system follows the apparent motion of the sun. Diagram 1 shows the geometry of the heliostat and diagram 2 its construction. On the base supported by three adjustable screws there is a level, a horizontal disk and two supports (n1 and n2) that hold the cylinder containing the clock system and the metal mirror. On the support n1 there is a protractor for regulating the inclination of the apparatus according to the local latitude. On the face of the clock system there are indicators of the present hour and minute time. The clock system rotates the metal mirror keeping account that the sun's ray deflects by twice as much as the mirror, the angle of reflection being equal to the angle of incidence. There are two arcs on the top, the declination arc B divided in day month and degree (M,J,J,A for May, June, July, August) and the reflection arc A located toward the exterior of the apparatus, The two arcs carry forks which together guide the mirror in the calculated movement.

ISCRIZIONI

1. Sulla superficia dell'orologio è inciso: "J. T. Silbermann inv tur¶
   Fait par J. Duboscq a Paris¶
   N. 123"

BIBLIOGRAPHY

• [1] E. Gelcich,"Ottica", Ulrico Hoepli - Editore - Milano, 1895. Pagine: 63-66.
• [2] Catalogne Maison Jules Duboscq,Fondé en 1819, Par Soleil Père.
• [3] Daguin, P.A.,'Traité de Physique', Paris (1862).§1920, Pagine:68-70
• [4] Mills, Allan A.(1982) 'Portable heliostats (Solar illuminators)', Annals of Science, 43:4, 369-406
• [5] J. H. Pepper, "Cyclopaedic Science Simplified", 1869 F. Warne and Co., Scribner, Welford, and Armstrong (London, New York) Page 87. URL [ http://www.archive.org/details/cyclopaedicscien00pepprich ]
• [6] Museo degli strumenti per il calcolo:Eliostato di Silbermann URL [ http://www.fondazionegalileogalilei.it/museo/collezioni/strumenti_scientifici/astronomia/schede_astronomia/eli_silbermann.html ]

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