650
Her Majesty.” Until 1851, he worked together with the
chemist Thomas Malone, continuing independently un-
der the name of Henneman & Co. until 1858. During the
1860’s, Henneman worked as an operator in the studios
of photographers such as Napoleon Sarony and Robert
White Thrupp in Birmingham. Henneman died on 18
January 1898 at 18 Half Moon Street, London, where
he had run a lodging house since around 1872.
See also: Talbot, William Henry Fox.
Further Reading
Asser, Saskia, “Nicolaas Henneman,” in Lexicon Geschiedenis
van de Nederlandse Fotografi e [Lexicon History of Dutch
Photography], 29 (November 1997), edited by Ingeborg Th.
Leijerzapf, Antwerpen: Voetnoot Publishers.
Buckland, Gail, Fox Talbot and the Invention of Photography,
London: Scolar Press, 1980.
Gill, Arthur T., “Nicholas Henneman 1813–1893,” in History of
Photography, 4/4 (October 1980), 313–322.
Gill, Arthur T., “Nicholas Henneman. Correspondence from
Arthur T. Gill,” in History of Photography, 5/1 (January
1981), 84–86.
Keeler, Nancy, “Illustrating the ‘Reports by the Juries’ of the
Great Exhibition of 1851; Talbot, Henneman, and Their Failed
Commission,” in History of Photography, 6/3 (July 1982).
Schaaf, Larry J., H. Fox Talbot’s The Pencil of Nature, An-
niversary Facsimile, New York: Hans P. Kraus Jr., Fine
Photographs, 1989.
Schaaf, Larry J., Out of the Shadows. Herschel, Talbot & the
invention of Photography, New Haven/London: Yale Uni-
versity Press, 1992.
Schaaf, Larry J., The Photographic Art of William Henry Fox
Talbot, Princeton/Oxford: Princeton University Press, 2000.
Snow, V.F. and D.B. Thomas, “The Talbotype Establishment at
Reading 1844–1847,” in The Photographic Journal 106/2
(February 1966), 56–67.
HENRY, PAUL (1848–1905) AND
PROSPER (1849–1903)
The two brothers, Paul Pierre Henry (1848–1905) and
Prosper Mathieu Henry (1849–1903), were born in Nan-
cy a year apart. Paul Pierre was born on August 21, 1848
and his younger brother Prosper Mathieu on December
10, 1849. Coming from a modest family, little is known
of their training other than that they completed their
elementary studies within the framework of a catholic
school. When they fi nished schooling, each 16 years old,
they became employees of the Service Météorologique
des Prévisions, which had been recently created at the
Observatory of Paris. Quickly, they learned the skills of
their astronomical vocation and were passionate about
the construction of optics intended for telescopes. While
they performed their daily tasks at the Observatory,
they developed their research on optics in a workshop
that they arranged in their house in Neuilly and later at
Montrouge.
In 1871, Charles-Eugene Delaunay, then director of
the Observatory, having learned of their work on optics,
transferred them from the service of Meteorology to the
department of Astronomy in order to continue unfi nished
work left by the death of the astronomer Jean Chacornac.
From 1852, at the Paris Observatory, they were engaged
in the production of astronomical charts which, it was
hoped, would help in the search for asteroids and small
comets. The establishment of such charts involved a
genuine tour de force. The observer had to measure the
positioning of each star and transfer it by drawing on
sheets which were then engraved. In the areas close to
the Milky Way, there are 18,000 stars in a portion of
fi ve degrees of the celestial vault. With such a concen-
tration of stars, the limits of the ordinary processes of
observations were quickly reached. In 1884, the idea
came to Paul and Prosper to substitute observations by
the naked eye with a method of photographic recording
based on that of the American astronomer Pickering
who obtained in 1882 a perfectly readable image of the
nebula of Orion.
The fi rst results achieved by the Henry brothers
were surprising. On certain negatives, one could count
1500 stars that were invisible to the naked eye. The
advantages that the delicate plate represented in the
development of the celestial charts did not escape those
in charge of the observatory for Paris, in particular its
new director, the admiral Ernest Mouchez. The utility
of the process was not in any doubt: “ Using photogra-
phy, one will be able, to obtain in one hour a Sky chart
of the same quality as the ecliptic Chart, which would
require several months of an assiduous work by the
ordinary processes.”
Other observatories considered at the same time the
possibility of a photographic chart of the sky. In order
to prevent all isolated approaches, Mouchez considered
it necessary to found an international scientifi c collabo-
ration. In 1886, he submitted the photographic chart of
the sky for the approval of the Academy of Science, an
international Congress. The following year, 15 directors
of the selected observatories found themselves in Paris
to agree on the methods of its execution. The inaugural
speech that Mouchez gave summarized for them the
posted ambitions of the project: “It will be a glorious
and unforgettable date, as will be unforgettable in the
history of Astronomy the imposing work which we
want to bequeath to the future generation’s work, one
which will be able to defi ne as the Inventory exact and
as complete as possible of the perceptible universe in
the end of the 19th century.”
It was however necessary to await the meetings of
1889 and 1891 to reach an agreement among all the
observatories. Eighteen of them ultimately held out,
those of Greenwich, the Vatican, Catane, Helsingfors,
Potsdam, of Oxford, of Paris, Bordeaux, Toulouse,