HELIOGRAPHS
a signalling device by which sunlight is reflected in flashes from a movable mirror.
a telescopic apparatus for photographing the sun.
a type of early photographic engraving made using a sensitized silver plate and an asphalt or bitumen varnish.
send (a message) by heliograph
take a heliographic photograph of
a telescopic apparatus for photographing the sun.
a type of early photographic engraving made using a sensitized silver plate and an asphalt or bitumen varnish.
send (a message) by heliograph
take a heliographic photograph of