Heliostat

George Johnstone Stoney (1826-1911), whose most important work was the conception and calculation of the magnitude of the atom for which he proposed the name 'electron', designed this cheap compact direct-drive heliostat. It was manufactured from around 1880 by Yeates and Son of Dublin.

The description of how to use the heliostat is on the accompanying leaflet: wind up the clock in the base, set the arc to the latitude, stand the instrument level, set it due north and south, turn the Sun arm towards the Sun and adjust it so the rays pass through the little sight hole, forming a bright spot of light in the centre of the disc. Then turn the mirror to the direction required, and 'the adjustment will be complete'.

The first satisfactory solar telescope was attached to the heliostat developed by Leon Foucault (1819-1868), who invented the linkage which converted the steady motion of a clock into the complex motion needed to correct the variation in the Sun's position during the day. The heliostat mirror is flat, so that it does not focus the light, but reflects sunlight into a fixed solar telescope.

Record details

To search on related items, click any linked text below.