  Broad-band observations of the solar photosphere began in Meudon in 1875
under the auspices of Jules Janssen. For his part, Henri Deslandres initiated
imaging spectroscopy in 1892 at Paris observatory. He invented, concurrently
with George Hale in Kenwood (USA) but quite independently, the
spectroheliograph designed for monochromatic imagery of the solar atmosphere.
Deslandres developed two kinds of spectrographs: the ''spectroh{\'e}liographe
des formes'', i.e. the narrow bandpass instrument to reveal chromospheric
structures (such as filaments, prominences, plages and active regions); and the
''spectroh{\'e}liographe des vitesses'', i.e. the section spectroheliograph to
record line profiles of cross sections of the Sun with a 20''-30'' spatial
step. This second apparatus was intended to measure the velocities (more
exactly the Dopplershifts) of dynamic features. Deslandres moved to Meudon in
1898 with his instruments and tested various combinations, in order to improve
the spectral and spatial resolutions, leading to the final large quadruple
spectroheliograph in 1908. CaII K systematic observations started at this date
and were followed in 1909 by H$\alpha$. The service was organized by Lucien
d'Azambuja and continues today. Optical and mechanical parts were revisited in
1989 and the digital technology was introduced in 2002. Full line profiles are
registered for all pixels of the Sun since 2018, so that the instrument
produces now data-cubes. The collection is one of the longest available (more
than 100 000 observations). It contains sporadic images from 1893 to 1907
(during the development phase) and systematic observations along 10 solar
cycles since 1908, in H$\alpha$ and CaII K lines. This paper summarizes 130
years of observations, instrumental research and technical advances.

Instrumentation and Methods for Astrophysics;Solar and Stellar Astrophysics