Museo Galileo
Virtual Museum
Solar mirror
    • Setting:
      Room XI
    • Maker:
    • Place:
    • Date:
      first half 19th cent.
    • Materials:
      brass, glass, cardboard, leather
    • Dimensions:
      plate 194x142 mm, mirror 160x75 mm, tube length 270 mm
    • Inventory:
    • Solar mirror (Inv. 3228)

The portaluce [solar mirror] is an instrument for reflecting solar rays into a room. It consists of a brass plate fitted with a rotating disk bearing a mirror on one side and a tube on the other. The device is installed in an aperture—usually made in a window—with the mirror facing out. By rotating the disk and adjusting the inclination of the mirror with a screw, one can align the instrument so that the Sun's rays are reflected into the tube. The tube contains a diaphragm that admits only a thin beam of light into the room. The effects of the apparent motion of the Sun are corrected by periodically adjusting the mirror's position.