DRAPER
DRAPER
DRAPER, John William, scientist, was born
at St. Helens, near Liverpool, England, May 5,
1811 ; son of the Rev. John Christopher and Sarah
(Ripley) Draper. He attended a Wesleyan acad-
emy at Woodhouse Grove, and in 1829 studied
chemistry at the University of London. He was
married in 1831 to
Antonia Coetana de
Paiva Pereira, daugh-
ter of Dr. Gardner of
Rio Janeiro, attend-
ing physician of Dom
Pedro I., Emperor of
Brazil. Her mother
was the daughter of
Sefior de Paiva
Pereira of Portugal,
whose great-grand-
father was captain of
Vasco de Gama's ship
M'heu he circumnav-
igated Africa in 1497.
Before the Revolu-
tionary war some of John W. Draper's an-
cestors on his mother's side had emigrated to
America, and had founded a small Wesleyan
community in Virginia. Subsequently others of
the family had joined them ; and after the death
of his father in 1829 John "William was urged by
these relatives to go to America. Accordingly in
1832 he settled in Christianville, Mecklenburg
county, Va. His sister Catherine gave lessons in
music and painting, and thus enabled him to take
the course of lectures in the medical school of the
University of Pennsylvania, from which he was
graduated in 1836. In the same year he became
professor of chemistry and physics at Hampdeu-
Sidney college, Va. ' He resigned his chair in 1838
to accept that of chemistry and physiology in the
University of the city of New York, which he
held until his death. In 1841 he was instrumen-
tal in founding the University medical college, in
which he was professor of chemistry until 1881,
and chief executive officer, 1850-73. Before the
termination of his medical course his experiments
resulted in the discovery that gases pass more
or less rapidly, in some cases instantaneously,
through barriers such as bubbles or membranes
"having no proper pores." This showed that
what had been knowTi as endosmosis was a process
not confined to liquids, and elucidated the method
of the oxygenation of the blood. He made this
discovery the subject of his graduation thesis,
which was published by the faculty, and at once
attracted the attention of the scientific world.
He continued his experiments, and contributed
papers on their results to the principal scientific
journals of America. He explained by practical
demonstration the circulation of the sap in j^lants
and of the blood in animals, as being results of
osmotic action ; and in 1844 published a volume
entitled " A Treatise on the Forces that Produce
the Organization of Plants. ' ' It combated the ex-
istence of the so-called "vital force " of physiolo-
gists. In 1839 he made the first daguerreotype of
the human face, his sister being the sitter, and
in 1840 made a daguerreotype of the moon one
inch in diameter. He associated himself with
Prof. S. F. B. Morse, then a portrait painter in
the university building, in carrying on the experi-
ments which resulted in the invention of the
electric telegraph, aiding that inventor in the
construction of batteries and other apparatus. He
daguerreotyped the prismatic spectrum in 1842
and the diffraction spectrum in 1843. In the
latter year he also invented a chlor-hydrogen
photometer and a ferric-oxalate photometer. In-
vestigating the phenomena of the solar spectiiim
he doubled the number of discovered lines. In
1847 he studied the phenomena of incandescence
and ascertained that it is only the spectrum of a
gaseous body that shows lines at all. He thus
anticipated Kirchoff"s conclusions by thirteen
years. In 1848 he made a spectrum analysis of
various flames, proving that of whatever origin
they yield all the colors of the spectrum. The
finest telescopes failed to resolve many of the
nebulee into distinct points of light. Astronomers
had been puzzled as to the explanation of this.
Dr. Draper's discoveries in spectrum analysis
showed that if the spectrum of an irresolvable
nebula consist of bright lines, it is a gaseous
body ; if on the other hand the spectrum is con-
tinuous, that body is an incandescent solid ; thus
affording means of inferring the constitution of
the remote heavenly bodies. He was the first to
make microscopic photographs, 1858. In 1872 he
experimented on the distribution of heat and
chemical force in the solar spectrum. For his
" Researches in Radiant Energy " he was
awarded by the American academy of arts and
sciences in 1875 the Rumford gold medal. He
was a member of many scientific societies, includ-
ing the National academy of sciences ; the Ameri-
can philosophical society ; the American academy
of arts and sciences ; the Accademia dei Lincei of
Rome ; and the Physical society of London. The
College of New Jersey conferred upon him the
degree of LL.D. in 1860. His bibliography, com-
prising books, scientific memoirs, lectures and
addresses, includes ninety-two titles. These may
be found in Professor Barker's memoir of Pro-
fessor Draper, read before the National academy
of sciences. The books are as follows : Elements
of Chemistry, by Robert Kane ; American edition
edited by J. W. Draper (1842) ; A Treatise on the
Forces tohich Produce the Organization of Plants
(1844) ; Text-bool- on Chemisti-y (1846) ; Text-book
