  The spectroheliograph was invented independently by Henri Deslandres (France)
and George Hale (USA) in 1892, following the spectroscopic method suggested by
Jules Janssen in 1869. This instrument is dedicated to the production of
monochromatic images of the Sun in order to reveal the structures of the
photosphere and the chromosphere at various altitudes. Sporadic observations
started in Paris, but Deslandres moved soon to Meudon and designed, with Lucien
d'Azambuja, an universal and powerful instrument, the quadruple
spectroheliograph. It was devoted to systematic observations of the Sun (the
long-term activity survey since 1908) and scientific research in solar physics.
This paper describes the instrument and presents some original observations
made with the high dispersion 7-metre spectrograph. It was dismantled in the
sixties, but the solar patrol continued with the 3-metre chambers with
H$\alpha$ and CaII K lines, and is still working today with the numerical
version of the spectroheliograph.
