90
a negligible part of the solar system, like the Moon,
Sun, and at certain times, eclipses. In 1865 Rutherfurd
was forced to recognize that “the results obtained by
photography” were far from “able to compete with the
human vision.” Problems varied according to objects
being photographed. For objects with weak luminos-
ity like the Moon and stars, the length of the exposure
times always constituted the principal diffi culty, often
forcing the photographer “to compensate” manually
the rotational movement of the ground, which left the
image at the mercy of atmospheric variations. For tak-
ing images of the Sun, the principal obstacle resided in
the very strong luminosity, forcing the photographer to
opt for less sensitive materials, like albumen-on-glass,
daguerreotype, screens to reduce the power of the actinic
rays or to reduce the durations considerably, which led
to the development of mechanical shutters. The limits
of photography were obvious at the time of the transit of
Venus, 1874. The scarcity of the phenomenon, since the
last passage had taken place in 1769, like the importance
at stake, the goal of which was to determine the precise
moment Venus appeared to make contact with the Sun,
and to precisely calculate the distance from the Sun to
the Earth, explained the extent to which photographer
went to capture this. Sixty two photographers, equipped
with numerous cameras were sent to the four corners
of the world, disseminated in two hemispheres, and to
eighty different sites of observation. They represented
the only international effort ever made to observe “a
simple” astronomical phenomenon. On this occasion,
Frenchman, Jules Janssen, took his photographs repeat-
ing camera which enabled him to take 48 images in 72
seconds on the same plate. During the simple passage of
1874, several hundreds of stereotypes were taken on the
various sites. Often of very good quality, however not all
were successful. After long years spent analyzing them,
in France and abroad, it was necessary to confront the
obvious; photography was not better than visual obser-
vations and that the distribution of cameras to capture the
measurements between Venus and the sun had made it
impossible to achieve the precise measurements needed.
During the international conference which occurred in
Paris in October 1881 to discuss the observations the
passage of 1882, the decision was made to return to
traditional observation methods for the next year’s im-
ages. These results did not prevent the astronomer Jules
Janssen from proclaiming, based on an expression of
Biot’s in 1839, that at the end of 1870, photography had
become the “true retina of the scientist.”
The beginning of the 1880s brought the general-
ized use of gelatine-bromide, a more sensitive process
than collodion, and with it, a type of photography that
made it possible to photograph the visible universe. In
January 1883, Andrew Ainslee Common, took the fi rst
images of stars one night in January in the suburbs of
London. Additionally, during the same period, the most
powerful telescopes made it possible to see stars as well.
Photography had acquired the status of an instrument
of discovery, making it possible to capture phenomena
that had before then, not been photographable, such as
Barnard’s with work comets. Photography also facili-
tated interest in the Milky Way for photographers like
Wolff, Barnard, Russell, Roberts, and Gould, all of
whom were interested in new planets as well. Owing
to Lowell’s initiative, an observatory dedicated entirely
to the study of Mars was created in Flagstaff, Arizona
where photography played an integral part.
The process of developing celestial charts, which was
previously done meticulously by hand, was replaced
by the favored alternative of the photographic plate.
In fact, several observatories launched companies that
reproduced these charts. Vis-a-vis with these disordered
initiatives, the need for a harmonization was profi led,
and in 1887 was held at the observatory of Paris, where
the fi rst astrophotographic Congress International met
“for the lifting of the sky chart.” With this occasion, its
director, the admiral Mouchez, summarized the intended
ambitions of the project, that “the inventory [be] exact
and as complete as possible of the perceptible Universe
at the end of the 19th century” allowing these photogra-
phers to draw up a sky chart up to stars of the 14th size.”
Eighteen observatories throughout the world promised
participation in this international project.
The company however was large and complex
and relied upon a too new technique, which became
quickly obsolete. The amalgamation, throughout the
1890s, required harmonization in terms of materials
and methods used. Finally established out of this though
was the equatorial method developed at one point by
the Henry brothers at the Observatory of Paris. In spite
of the importance of the company, and the means put
into it, the exorbitant cost of the operation mellowed
the enthusiasm of some. In the day before of the First
World War only the observatories in Paris, of Toulouse
and Algiers had partially completed work. Three-quar-
ters of a century after its launching, in 1970, the project
was defi nitively abandoned. In the last quarter of the
century however, other atlas companies experimented
with photography as well.
At the physical observatory of astronomy of Meudon,
the celestial service of photography created by Jules
Janssen in 1876 undertook a systematic study of the
solar surface. Those principal results were published,
between 1896 and 1905, in the astonishing Atlas de
photographies solaires 1903, which illustrated the
precise granulations of the surface of the star. In the
fi eld of lunar cartography, it was at the observatory of
Paris, 1890, that L’Atlas photographique de la Lune was
started. Composed of 71 boards from 6,000 stereotypes,
published in volumes from 1896 to 1910, the unit still