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IRA SPRAGUE BOWEN
December 21, 1898-Februa7:y 6, 1973
BY HORACE W. BABCOCK
IRA SPRAGUE BOWEN was one of the outstanding physicists
and astronomers of the twentieth century. He was giftec!
with exceptional physical insight and with a compelling con-
cern for funciamentals from which he seldom permitted him-
self to be divertecI. As a pioneer in ultraviolet spectroscopy he
discovered, with R. A. Millikan, evidence that led to the con-
cept of electron spin in the vector mode] of the atom. He
solver! the long-standing mystery of the "nebulium" lines in
the spectra of gaseous nebulae, showing that they were "for-
bidden" lines of ordinary elements. He was a master of ap-
plied optics who was responsible for successful completion of
the 200-inch Hale Telescope and for many ingenious crevices
or optical systems that contributed enormously to mankincl's
observations of the universe.
Bowen was director of the Mount Wilson and Palomar
Observatories for eighteen years. Here he took the leacI in
developing a major organization for research and education
while at the same time closely supervising details of observa-
tory operations. On a wider scale, he accomplishecI much to
broaden the opportunities for astronomers generally and to
increase the number and efficiency of astronomical facilities.
FAMILY BACKGROUND AND SCHOOLING
The Bowen family traces its beginning in New England to
Richard Bowen, who left Wales and settlecI in Rehoboth,
83
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84 BIOGRAPHICAL MEMOIRS
Massachusetts in 1643. During the Revolutionary War some
members of the family were Tories and were forced to emi-
grate to Canada. Later they returned to Washington County,
New York. Ira Bowen's great-grancifather, Aaron Bowen,
pioneered! in Steuben County, in the western part of the state.
His grandfather, William H. Bowen, grew up on a farm in
this region and married Juliza Cotton, whose family was
I-ikewise of New England origin and had pioneered in the
same section of the state. After spending his early years on
the farm, Tra's father, lames H. Bowen, received his educa-
tion at the local high school and at the Geneseo State Normal.
He then became a preacher in the Wesleyan Methodist
Church, a small denomination with fundamentalist doctrines
and strict codes of conduct. James Bowen married Philinda
Sprague, who tract grown up in the same rural community of
Haskinsville in Steuben County and hacl completed her edu-
cation at the Geneseo State Normal.
Ira was born December 2l, IS98 at Seneca Falls, New
York, where his father was at the time pastor of the local
church. Two years later the family, including Ira's older
brother, Ward, moved to MilIview, a small village in Sullivan
County, Pennsylvania. While Tra was quite young, his father
became business agent of the Wesleyan Methodist Church;
the resulting responsibilities required frequent moves be-
tween Houghton and Syracuse, with the result that from
1905 to 1908 Tra dicI not attend school but was taught at home
by his mother, who was a licensed teacher in New York State.
Following the death of his father in 190S, the boy's education
was continued at Houghton Wesleyan Methodist Seminary,
where his mother had obtained a position as a teacher. She
later became principal of the high school department.
During his high school years, Ira (or Ike, as he was known
to his friends) took considerable interest in popular science as
represented by Popular Mechanics and Scientific American. He
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IRA SPRAGUE BOWEN
85
also played with lenses, wires, and batteries to the extent
permitted by the very limitecI family finances. He graduated
from the high school in 1915 as valedictorian of a class of
seventeen.
The first three years of Ike Bowen's college courses were
in the junior college that formed part of Houghton Sem-
inary. All of the courses in mathematics, physics, ant! astron-
omy were taught by the president, I. S. Luckey, who was a
most effective teacher and who was largely responsible for
the unusually high scholastic standarcis at the school. For
these three years Bowen had charge of the laboratory of the
high school physics course; the income earned in this way was
used to pay his tuition.
His early interest in science deepenecI cluring Bowen's
first college years. It was no doubt stimulatecI by the ingenuity
requires! to devise suitable experiments with the limiter]
equipment available, as well as by the formal courses. Follow-
ing a connection establishecl by Luckey, Bowen transferred to
Oberlin College for his senior year and received the A.B.
degree in June 1919. While at Oberlin he came under the
direction of Professor S. R. Williams, whose sympathetic col-
laboration with his students in research projects was respon-
sible for the continuation of many of these students in ad-
vancec! stucly anct research. In a project of this sort, Bowen
stucliecI the magnetic and magnetomechanical properties of
samples of manganese steel supplied by Sir Robert HacIfield,
with whom he eventually publishecI the results in the Proceed-
ings of the Royal Society. During this year he also assisted in one
of the general physics laboratories and gave some time to the
Students Army Training Corps, in which he had enlisted
before the end of World War I.
In the fall of 1919, having been awarded a scholarship,
Bowen took up graduate studies at the University of Chicago.
In the two years that he remained there he attenclecl all of the
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86
BIOGRAPHICAL MEMOIRS
very comprehensive group of courses given by A. A. Michel-
son on classical physics and R. A. Millikan on modern physics,
as well as many other courses in the department. These con-
tacts, and the involvement in a major physics department
during a period of extraordinary progress, undoubtedly had
a deep and lasting influence. In later life Bowen insisted that
research should be aimed incisively at a welI-defined, funda-
mental problem; he was intent on understanding the basic
physics and had little patience with mere data-gathering pro-
grams, which he characterized as "weather-bureau-type"
. .
activity.
RESEARCH AND TEACHING
At about the time of Bowen's arrival at the University of
Chicago, Millikan's laboratory assistant, Dr. Ishida, an-
nounced his intention of leaving the University and return-
ing to Japan. Bowen immediately accepted the offer of this
position, which he took up on January I, 1920. His first
duties were to assist Tshida in the completion of his mea-
surement of the viscosities of several gases by the oil-drop
method. Upon Ishida's departure, however, Bowen was
transferred to spectroscopic studies in the extreme ultraviolet
using the vacuum spectrograph that had been developed
by R. A. Sawyer and G. D. Shallenberger under Millikan's
direction. At about this time significant improvements were
introduced in the methods of ruling diffraction gratings,
permitting extension of the shortward limit observable in the
laboratory to about 150 angstroms. In the winter of 1920 and
1921 Bowen systematically photographed, in this newly avail-
able region, the spectra of most of the first twenty elements
of the periodic table. The results were published jointly with
Millikan in 1924. Many interesting surprises occurred in this
first survey of the new region, such as the discovery that
chemically pure aluminum and magnesium electrodes gave
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IRA SPRAGUE BOWEN
87
practically identical spectra in the region between 300 ~ ant!
1200 A. At first the investigators even consiclerec! attributing
this finding to some transmutation of one element into
another by the powerful condensed spark that was used. But
more reflection anti investigation showed that these common
lines were due to oxygen, always present on the surface of
these easily oxidizable metals. The difference in behavior in
the new region and in the spectral regions previously ex-
plored results from the presence of all the strong lines of
these metals in the older, long wavelength range.
In 1921 George E. Hale persuaded Millikan to move to
the California Institute of Technology as chairman of its
executive council and director of the Norman Bridge Labora-
tory of Physics, then nearing completion. Arrangements
were made for Bowen also to make the move ant] to continue
as Millikan's assistant in the new physics group at Caltech.
One of the inducements offerer! by Hale was the proximity of
the emergent scientific school to the Mount Wilson Observa-
tory of the Carnegie Institution of Washington, where the
largest telescopes in the world were being used by an active
staff in a variety of investigations in astrophysics and cosmol-
ogy. More specifically, Hale promiser! Millikan that diffrac-
tion gratings would be provided from the new ruling ma-
chine that had just gone into operation at the Pasadena head-
quarters of the Observatory.
During the first year after the move to Caltech, Bowen
taught a course in general physics, using a lecture room in
Throop Hall because the Norman Bridge L aboratory was still
uncler construction. He also participates] with Millikan in
research on cosmic rays. The program involved the design
and use of instruments carrier! to high altitudes by sounding
balloons, the actual flights being made from San Antonio,
Texas. The researchers obtained the first record from souncI-
ing balloons of cosmic rays and fount! definite evidence for
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88 BIOGRAPHICAL MEMOIRS
an increase of intensity with altitude. Aerial observations had
already been made by Hess and Kolhorster, but because they
user! manned balloons they were limiter! to lower altitucles.
Bowen also participated with R. M. Otis in measurements of
cosmic-ray intensity in the High Sierra of California. They
used detectors that were lowered into the waters of mountain
lakes at altitucles of some 12,500 feet, such that the water
shielded the instruments from local radioactivity of the rocks.
A love of the mountains stayed with Bowen all his life, but his
principal research interests lay in spectroscopy, to which he
soon returned.
With the completion of the physics laboratory, apparatus
couIct be assembled for the continuation of the ultraviolet
studies. An exceptionally fine grating was indeecl provided by
I. A. Anderson of the Mount Wilson Observatory. This grat-
ing gave much higher resolution than had hitherto been ob-
tained in this region anal macle possible the studies of the fine
structure of many lines in the extreme ultraviolet that were
carried out by Bowen with the vacuum spectrograph in 1923
and 1924.
At about this time, Paschen and R. H. Fowler almost
simultaneously macle their analyses of highly ionized Al ITI
ant] Si IV, anct Bohr publisher! his discussion of penetrating
and nonpenetrating orbits. Applying these results to their
new data, Bowen ant! Millikan found it possible to make an
analysis of B ITI. From further stucties ma(le early in 1924
they were able to show that the so-called regular anti irregu-
lar cloublet laws, developed earlier for X-ray spectra, applied
equally well to optical spectra when isoelectronic sequences
(series of ions of the same electronic structure but differing
nuclear charge) were used. This discovery at once ma(le pos-
sible a direct correlation between optical and X-ray spectra
ant! therefore between the atomic-structure formalisms cle-
veloped from these two types of spectra. The results of this
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IRA SPRAGUE BOWEN
89
correlation constituted part of the evidence that later resulted
in the introduction of the important concept of the spinning
electron by UhIenbeck and Goudsmit.
The doublet laws provided a very powerful too! for the
analysis of highly ionized atoms. In 1925 and 1926 Bowen
and Millikan applied these laws to the analysis of their new
data and were able to obtain partial analyses of Be I, Be Il.
B Il. B IIT, C IlI, C IV, P III, P IV, P V, S IV, S V, S VI, CT
V, C l VI, C ~ VIT, C 1 VITI, Y lIl, and Zr IV. In this research,
the heavier part of the load fell on Bowen, who produced and
measured the spectrograms and analyzed the data. Millikan
was exceedingly busy with the administration of the Institute
anc! of the Norman Bridge Laboratory, as well as with a
variety of other research efforts. He would occasionally cirop
in to keep in touch. When Bowen was ready, he would say to
Millikan, "I've got an article. How about coming arounct
tonight?"* Millikan would appear at about nine o'clock in
Bowen's office, and the two would work until midnight writ-
ing the paper.
For several years after coming to Caltech, Bowen heal the
title of instructor and research assistant to the director of the
Norman Briclge Laboratory of Physics. His teaching assign-
ment was to instruct one of the undergracluate sections of
twenty students in physics. In 1924 the practice was initiated
of assigning the top men of the sophomore class to section A,
the honor section, and Bowen was given this section. Much
later he commented that "l never had quite such a run for my
money. In the section were Ed McMilIan, Robley Evans, and
several others who later became heads of departments or
university presidents. Keeping ahead of that group took
.
quite some time. ~
*Interview with Charles Weiner, Center for the History of Physics, American
Institute of Physics.
Sibs.
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go
BIOGRAPHICAL MEMOIRS
Bowen continued with undergraduate teaching in physics
until 1929, when he took over the teaching of graduate
courses in optics and spectroscopy. He became assistant pro-
fessor of physics in 1926, associate professor in 192S, and
professor in 193 I.
Under the pressures of research and teaching, Bowen
found little time to proceed with the formal requirements for
the Ph.D. degree, although he finally received it in 1926, by
which time he had already published some twenty articles.
language examinations were required, and partly for this
reason he took a month's vacation in the summer of 1925,
spending some of the time reading Sommerfeld's Atombau
und Spectra1!linien in German. (He had already passed the
French examination.) His thesis, somewhat surprisingly, was
on the subject of "The Ratio of Heat Losses by Conduction
and by Evaporation from Any Water Surface." This came
about because Bowen had been assigned to guide the thesis
work of another graduate student, an older man who had
been with the weather bureau and who proposed to do a
thesis on evaporation but later lost interest. Bowen's interest
grew to the extent that he worked out a formula for the ratio
of heat lost by evaporation and by conduction to the air.
showing that this ratio can be determined uniquely from the
temperature of the air, the temperature of the water, and the
humidity. This quantity, known as the Bowen ratio, is to be
found in the literature of meteorology and has been of use in
oceanography. His ratio method is now commonly used to
measure the evaporation from plant, soil, and water surfaces.
As Bowen said later, "When ~ got ready to take my degree,
that was the paper that was going to press, so it became my
thesis."* His subject was undoubtedly a novel one for the
faculty pundits including P. Epstein, R. C. Tolman, and
Millikan who sat on his examining committee.
* Ibid.
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IRA SPRAGUE BOWEN
9
In the middle 1920's the vector model of the atom to
account for complex spectra was developed by Russell,
Saunders, Pauli, Hund, and others. Bowen applied this
theory to the analysis of the more complex spectra of the
elements in the first row of the periodic table, using again the
data accumulated from the use of the high-resolution spec-
trograph. It was thus possible for him in 1926 to fix the low
terms of C Il. N III, O IV, N II, O IlI, F IV, O Il. F [II, F
II, and F I. This, as it turned out, was preliminary to his most
outstanding discovery, the identification of the so-called
"nebulium lines" in the spectra of galactic nebulae. These two
bright green lines hacI been a puzzle to spectroscopists since
their discovery by Huggins some sixty years earlier. In paral-
lel with the bright yellow line in the spectrum of the sun's
corona, which had been attributed to an unknown element
(helium) before the element was discovered on earth, it hacT
been conjectured that nebulium was also an unknown but
real element. By 1920, however, spectroscopy in the X-ray
region had established the sequence of light elements. It was
clear that there was no room here for an unknown, while the
very strong nebulium lines could hardly be due to a rare
element at the heavy encI of the periodic table. Spectros-
copists were generally aware of the problem and were alert to
any {cads that might provide a solution.
H. N. Russell of Princeton was knowledgeable about these
matters. In 1927 the text of the classic Astronomy by Russell,
Dugan, and Stewart appeared, in which Russell made the
suggestion that "The nebular lines may be emitted only in a
gas of very low density. This wouIcl happen, for example, if
it took a relatively long time for an atom to get into the right
state to emit them, and if a collision with another atom in this
interval prevented the completion of the process. In such a
case, it might require a great thickness of the very rarefied
gas to emit these lines strongly enough to be visible" [p. 8381.
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92
BIOGRAPHICAL MEMOIRS
Bowen bought the two volumes of Astronomy and thus
became aware of Russell's summary. Later he related that one
evening he came home from the laboratory at about nine
o'clock and while preparing for bed was thinking about the
energy levels of O I! ant! O ITI anct the "forbicIden transi-
tions." According to the theory, there was no way for the
atom to get from the D or F states to the S (Iowest or ground)
state except through collisions. In a very rare gas, as in a
nebula, the rate of collisions was insignificant. What, then,
happens to these atoms? Are they stuck forever in the D and
F states? Then it occurred to Bowen that, given enough time,
perhaps the atoms can, in fact, make the "forbicIden" jumps,
although at a low rate.
Bowen quickly dressed ant! returned to his office. Since
all the data on the energy levels were available in his records,
it was easy for him to take the differences and to compute the
wavelengths of the forbiciclen lines in a matter of minutes.
There they were, correct to a hundredth of an angstrom! "I
worked until midnight and had the answer when ~ went
home," * he said. The "nebulium" lines were in fact due to
forbiciclen transitions between low-lying energy levels of
singly and doubly ionized oxygen. The lines were intense
because of the immense volume of gas at low pressure in the
nebulae. The name "nebulium" couIc! be laid to rest. The
solution to the problem was wiclely accIaimecT ant! brought
well-deservecl recognition to its author.
The initial discovery explainec! half a clozen of the strong-
est lines in the spectra of gaseous nebulae, but there were
many other fainter lines that required years of work by
Bowen anc! others; some were regular permitted lines of
hydrogen ant! helium, but many were fainter forbidden lines
of various elements. Bowen continued the work for years,
* Interview with Charles Weiner.
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IRA SPRAGUE BOWEN
HONORS AND DISTINCTIONS
DEGREES
A.B., Oberlin College, 1919
Ph.D., California Institute of Technology, 1926
Sc.D. (honorary), Oberlin College, 1948
Ph.D. (honorary), University of Lund, 1950
Sc.D. (honorary), Princeton University, 1953
PROFESSIONAL APPOINTMENTS
Morrison Research Associate, Lick Observatory, 193~ 1939
Director, Mount Wilson Observatory, 1946-1948
Director, Mount Wilson and Palomar Observatories, 194~1964
National Astronomical Observatory Advisory Panel, 1953-1957
PROFESSIONAL AND HONORARY SOCIETIES
National Academy of Sciences, 1936
American Academy of Arts and Sciences, 1939
American Philosophical Society, 1940
Royal Astronomical Society, London (Associate), 1946-1973
Astronomical Society of the Pacific, President, 1948
AWARDS
109
Draper Medal, National Academy of Sciences, 1942
Potts Medal, Franklin Institute, 1946
Rumford Premium, American Academy of Arts and Sciences, 1949
Ives Medal, Optical Society of America, 1952
Catherine Wolf Bruce Gold Medal, Astronomical Society of the
Pacific, 1957
Distinguished Service Staff Member, Carnegie Institution of
Washington, 1964- 1973
Henry Norris Russell Lecturer, American Astronomical Society,
1964
Gold Medalist and George Darwin Lecturer, Royal Astronomical
Society, 1966
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10
BIOGRAPHICAL MEMOIRS
BIBLIOGRAPHY
1921
With Sir Robert Hadfield and S. R. Williams. The magnetic me-
chanical analysis of manganese steel. Proc. R. Astron. Soc.,
98:297-302.
With R. A. Millikan and R. A. Sawyer. The vacuum spark spectra
in the extreme ultra-violet of carbon, iron, and nickel. Astro-
phys. J., 53: 15~60.
1924
With R. A. Millikan. Extreme ultra-violet spectra. Phys. Rev.,
23: 1-34.
With R. A. Millikan. The series spectra of the stripped boron atom
(B III). Proc. Natl. Acad. Sci. USA, 10:199-203.
With R. A. Millikan. The fine structure of the nitrogen, oxygen,
and fluorine lines in the extreme ultra-violet. Philos. Mag.,
48:25~64.
With R. A. Millikan. The assignment of lines and term values in
beryllium II and carbon IV. Nature, 114:380.
With R. A. Millikan. The extension of the X-ray doublet laws into
the field of optics. Phys. Rev., 24:209-22.
With R. A. Millikan. Some conspicuous successes of the Bohr atom
and a serious difficulty. Phys. Rev., 24:223-28.
1925
With R. A. Millikan. The significance of the discovery of the X-ray
laws in the field of optics. Proc. Natl. Acad. Sci. USA,11: 119-22.
With R. A. Millikan. A possible reconciliation of Bohr's interpene-
tration ideas with Sommerfeld's relativistic treatment of elec-
tron orbits. Philos. Mag., 49:923-35.
With R. A. Millikan. The series spectra of the stripped atoms of
phosphorus (P V), sulphur (S VI), and chlorine (C1 VII). Phys.
Rev., 25:295-305.
With R. A. Millikan. The series spectra of two-valence-electron and
of three-valence-electron systems. Nature, 115:423.
With R. A. Millikan. The series spectra of two-valence-electron
atoms of phosphorus (P IV), sulphur (S V) and chlorine (C1 VI).
Phys. Rev., 25:591-99.
With R. A. Millikan. The series spectra of three-valence-electron
OCR for page 111
IRA SPRAGUE BOWEN
atoms of phosphorus (P III), sulphur (S IV) and chlorine (C1 V).
Phys. Rev., 25:60() 605.
With R. A. Millikan. New light on two-electron jumps. Proc. Natl.
Acad. Sci. USA, 11:32~34.
With R. A. Millikan. Relations of PP' groups in atoms of the same
electronic structure. Phys. Rev., 26:150-64.
With R. A. Millikan. Series spectra of the two-valence-electron
atoms of boron (B II) and carbon (C III). Phys. Rev.,26:31 () 18.
1926
With R. A. Millikan. Stripped oxygen O VI, the PP' group in O V
and new aluminum lines in the extreme ultra-violet. Phys. Rev.,
27:14~49.
With R. A. Millikan. High frequency rays of cosmic origin I. Sound-
ing balloon observations at extreme altitudes. Phys. Rev.,
27:353-61.
The ratio of heat losses by conduction and by evaporation from any
water surface. Phys. Rev., 27:779-87.
Vacuum spectroscopy. I Opt. Soc. Am., 13: 89-93.
With R. A. Millikan. Series spectra of beryllium, Be I and Be II.
Phys. Rev., 28: 256-58.
With S. B. Ingram. Wave-length standards in the extreme ultra-
violet spectra of carbon, nitrogen, oxygen, and aluminum. Phys.
Rev. 28:444-48.
With R. A. Millikan. The ionization potential of O II. Nature,
118:410.
With R. A. Millikan. Stripped yttrium (Y III) and zirconium (Zr
IV). Phys. Rev., 28:923-26.
1927
The series spectra of boron, carbon, nitrogen, oxygen, and fluo-
rine. Phys. Rev., 29:321-47.
Series spectra of ionized phosphorus P II. Phys. Rev., 29:51(}12.
With R. A. Millikan. Energy relationships and ionization potentials
of atoms of the first row of the periodic table in all stages of
ionization. Proc. Natl. Acad. Sci. USA, 13:531-34.
With R. A. Millikan. Spectral relationships of lines arising from the
atoms of the first row of the periodic table. Philos. Mag.,
4:561-80.
The origin of the nebulium spectrum. Nature, 120:473.
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112
BIOGRAPHICAL MEMOIRS
The origin of the chief nebular lines. Publ. Astron. Soc. Pac.,
39:295-97.
1928
The origin of the nebular lines and the structure of the planetary
nebulae. Astrophys. J., 67: 1- 15.
The life of atomic states and the intensity of spectral lines. Proc.
Natl. Acad. Sci. USA, 14:30-32.
Series spectra of chlorine, C1 II, C1 III, C1 IV, C1 V, and of Si II, P
III, and S IV. Phys. Rev., 31:34-38.
Series spectra of potassium and calcium. Phys. Rev., 31:497-502.
Series spectrum of sodium Na II. Phys. Rev., 31:967-68.
With D. H. Menzel. Forbidden lines in the flash spectrum. Publ.
Astron. Soc. Pac., 40:332~0.
1929
The presence of sulphur in the gaseous nebulae. Nature, 123:450.
With H. N. Russell. Is there argon in the corona? Astrophys. I.,
69: 19~208.
Additional lines in the spectra of C II and N II. Phys. Rev.
34:534-36.
1930
With R. A. Millikan. The significance of recent cosmic ray experi-
ments. Proc. Natl. Acad. Sci. USA, 16:421-25.
The presence of neutral oxygen in the gaseous nebulae. Phys. Rev.,
36:600-601.
1931
Spectrum of doubly ionized carbon C III. Phys. Rev., 38: 128-32.
With R. A. Millikan. Similarity between cosmic rays and gamma
rays. Nature, 128:582-83.
1932
Spectra of two- and three-valence-electron atoms, Si II, P III, S IV,
P IV, and S V. Phys. Rev., 39:~15.
Ionization of air by gamma rays as a function of pressure and
collecting field. Phys. Rev., 41: 24-31.
OCR for page 113
IRA SPRAGUE BOWEN
1933
113
With R. A. Millikan. Cosmic-ray intensities in the stratosphere.
Phys. Rev., 43:695-700.
With R. A. Millikan and H. V. Neher. New high-altitude study of
cosmic-ray bands and a new determination of their total energy
content. Phys. Rev., 44:24~52.
The aberrations of the concave grating at large angles of incidence.
J. Opt. Soc. Am., 23:313-15.
1934
The spectrum of fluorine, F II, F III, F IV. Phys. Rev., 45:82-86.
The spectrum of chlorine, C1 III, C1 IV, C1 V. Phys. Rev.,45:401-4.
The path of a secondary cosmic-ray particle in the earth's magnetic
field. Phys. Rev., 45:349-51.
The presence of neon in the nebulae. Publ. Astron. Soc. Pac.,
46: 145-46.
The excitation of the permitted O III nebular lines. Publ. Astron.
Soc. Pac., 46: 146-48.
The chemical composition of the nebulae. Publ. Astron. Soc. Pac.,
46: 186-87.
The singlet lines of C1 IV. Phys. Rev., 46:377.
With R. A. Millikan and H. V. Neher. Very high altitude survey of
the effect of latitude upon cosmic-ray intensities and an attempt
at a general interpretation of cosmic-ray phenomena. Phys.
Rev.,46:641-52. Also in: Papers and Discussions of the Interna-
tional Conference on Physics, London, 1:20~24.
Spectra of potassium, K IV and K V, and of calcium, Ca V and Ca
VI. Phys. Rev., 46:791-92.
1935
The spectrum and composition of the gaseous nebulae. Astrophys.
J., 81:1-16.
The low terms in Mn V and Fe VI. Phys. Rev., 47:92~25.
The extreme ultra-violet in astronomical sources. In: Zeeman Ver-
handlungen, pp. 55-62. The Hague: Martinus Nijhoff.
1936
The galactic nebulae. Scientia, 59:77-86.
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114
BIOGRAPHICAL MEMOIRS
Forbidden lines. Rev. Mod. Phys., 8:55-81.
With R. A. Millikan, S. A. Korff, and H. V. Neher. The latitude
effect in cosmic rays at altitudes up to 29,000 feet. Phys. Rev.,
50:57~81.
1937
With Everett F. Cox. Ionization of air by gamma-rays as a function
of pressure and collecting field II. Phys. Rev., 51:232-34.
With R. A. Millikan and H. V. Neher. Measurement of nuclear
absorption of electrons by the atmosphere up to 10~° electron
volts. Nature, 140:23.
With R. A. Millikan and H. V. Neher. The influence of the earth's
magnetic field on cosmic-ray intensities up to the top of the
atmosphere. Phys. Rev., 52:8(:~88.
The low terms in Cr III, Cr IV, Mn IV, and Fe V. Phys. Rev.,
52: 1153-56.
1938
With R. A. Millikan and H. V. Neher. New evidence as to the nature
of the incoming cosmic rays, their adsorbability in the atmo-
sphere, and the secondary character of the penetrating rays
found in such abundance at sea level and below. Phys. Rev.,
53:217-23.
With R. A. Millikan and H. V. Neher. New light on the nature and
the origin of the incoming cosmic rays. Phys. Rev., 53: 855-61.
The low terms in Co VI. Phys. Rev., 53:88~90.
The image-slicer, a device for reducing the loss of light at the slit of
a stellar spectrograph. Astrophys. I, 88: 1 13-24.
With A. B. Wyse. Hypersensitization and reciprocity failure. Publ.
Astron. Soc. Pac., 50:305.
With A. B. Wyse. New lines in the spectra of the gaseous nebulae.
Publ. Astron. Soc. Pac., 50:34~49.
With R. Minkowski. Effect of collisions on the intensities of nebular
lines. Nature, 142: 107~80.
1939
With B. Edlen. Forbidden lines of Fe VII in the spectrum of nova
RR Pictoris ~ 1925~. Nature, 143:374.
With A. B. Wyse. The spectra and chemical composition of the
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IRA SPRAGUE BOWEN 1 l;
gaseous nebulae NGC 6572, 7027, 7762. Lick Obs. Bull.
19: 1-16.
1940
5
With L. T. Clark. Hypersensitization and reciprocity failure of pho-
tographic plates. J. Opt. Soc. Am., 30:50~10.
1946
Metric photography: Field equipment and operations. In: Field
Testing of Rockets, pp. 47-89. Pasadena: California Institute of
Technology.
With F. A. Jenkins. Transparency of ocean water. I. Opt. Soc. Am.,
36:617-23.
Survey of the year's work at Mount Wilson. Publ. Astron. Soc. Pac.,
58:329-40.
1947
With P. Swings. Relative intensities of the coronal and other for-
bidden lines. Astrophys. J., 105:92-95.
Excitation by line coincidence. Publ. Astron. Soc. Pac., 59: 19~98.
Limiting visual magnitude. Publ. Astron. Soc. Pac., 59:25~56.
1948
Survey of the year's work at Mount Wilson. Publ. Astron. Soc. Pac.,
60:5-17.
The abundance of oxygen in the sun. Rev. Mod. Phys., 20: 10~12.
Survey of the year's work at Mount Wilson and Palomar Observa-
tories. Publ. Astron. Soc. Pac. 60:353-65.
The telescope at work. In: Palomar, fune 3, 1948. San Francisco:
Grabhorn Press. Reprinted in: Griffith Obs., 12: 121-23.
1949
The award of the Bruce Medal to Sir Harold Spencer Jones. Publ.
Astron. Soc. Pac., 61:61-62.
Survey of the year's work at the Mount Wilson and Palomar Obser-
vatories. Publ. Astron. Soc. Pac. 61:243-53.
1950
The 200-inch Hale Telescope. Bull. Am. Acad. Arts Sci., 3~4~:2-3.
OCR for page 116
116
BIOGRAPHICAL MEMOIRS
Final adjustments and tests of the Hale Telescope. Publ. Astron.
Soc. Pac., 62:91-97.
1951
Survey of the year's work at the Mount Wilson and Palomar Obser-
vatories. Publ. Astron. Soc. Pac., 63:~16.
Palomar Observatory. Sci. Mon., 73:141-49.
With Paul Merrill. The spectrum of RS Ophiuichi in May 1951.
Publ. Astron. Soc. Pac., 63:25~56.
With Paul Merrill. Forbidden lines in the spectrum of MWC 300.
Publ. Astron. Soc. Pac., 63:29~96.
1952
The spectrographic equipment of the 200-inch Hale Telescope.
Astrophys. J., 116: 1-7.
Optical problems at the Palomar Observatory. I. Opt. Soc. Am.,
42: 79~8~)0.
Some new tools of the astronomer. Observatory, 72: 12~37.
Mount Wilson and Palomar Observatories (Reports of Observa-
tories 1951-521. Astron. I., 57:184-85.
1953
Mount Wilson and Palomar Observatories (Reports of Observa-
tories 1951-52~. Astron. J., 58:25~61.
1954
The 200-inch Hale Telescope. Trans. Int. Astron. Un., 8:75~54.
Mount Wilson and Palomar Observatories (Reports of Observa-
tories 195~54~. Astron. I., 59:35~56.
Edwin P. Hubble, 188~ 1953. Science, 119:204.
1955
Wavelengths of forbidden nebular lines. Astron. J., 121:30~11.
Mount Wilson and Palomar Observatories (Reports of Observa-
tories 1954-55) Astron. J., 60:296-99.
Astronomical spectrographs: Past, present, and future. In: Vistas in
Astronomy, ed. Arthur Beer, vol. l, pp.400-406, London: Perga-
mon Press.
With L. H. Aller and R. Minkowski. The spectrum of NGC 7027.
Astron. I., 122: 62-71.
OCR for page 117
IRA SPRAGUE BOWEN
1956
117
Optics. Smithson. Contrib. Astrophys., 1: 1-3.
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tories 1955-56~. Astron. I., 61: 336-41.
1957
Instrumentation at Mount Wilson and Palomar Observatories.
Publ. Astron. Soc. Pac., 69:377-84.
1958
The Universe from Palomar. Griffith Obs., 22:6~78.
Astronomy in a changing world. In: Frontiers in Science, ed. E.
Hutchings, Jr., pp. 28~94. New York: Basic Books.
1960
John August Anderson, 1876-1959. Publ. Astron. Soc. Pac.
72:9~96.
John A. Anderson, astronomer and physicist. Science, 131 :64~50.
Wavelengths of forbidden nebular lines II. Astrophys. }.,13?: 1-17.
The 200-inch Hale Telescope. In: Stars and Stellar Systems, ed. G. P.
Kuiper and B. M. Middlehurst, vol. 1, Telescopes, pp. 1-15. Chi-
cago: Univ. of Chicago Press.
Schmidt Cameras. In: Stars and Stellar Systems, ed. G. P. Kuiper and
B. M. Middlehurst, vol. 1, Telescopes, pp. 43-61. Chicago: Univ.
of Chicago Press.
1961
Problems in future telescope design. Publ. Astron. Soc. Pac.,
73: 11~24.
1962
John August Anderson. In: Biographical Memoirs, 36:1-18. New
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~clences.
Robert Raynolds McMath (1891-1962~. Yearb. Am. Philos. Soc.,
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OCR for page 118
118
BIOGRAPHICAL MEMOIRS
1963
With L. H. Aller and O. C. Wilson. The spectrum of NGC 7027.
Astrophys. J., 138: 101~17.
1964
Explorations with the Hale Telescope. Science, 145:1391-98.
Le choix de sites d'observatoires astronomiques (site testing), in-
formal discussions. Int. Astron. Un. Symp. no. 19, ed. I. Rosch
pp. 15-34. Paris: Gauthier-Villars.
Telescopes. Astron . ~ ., 169: 816-25.
1965
With James B. Kaler and Lawrence H. Aller. Spectrophotometric
studies of gaseous nebulae. IV. The Orion Nebula. Astrophys.
J., 141:912-22.
1966
With Lawrence H. Aller and James B. Kaler. Spectrophotometric
studies of gaseous nebulae. VII. The ring planetary NGC 7662.
Astrophys. J., 144:291-304.
Optimum thermal effects for large domes. In: The Construction o)
Large Telescopes, ed. D. L. Crawford, pp. 17() 74. New York:
Academic Press.
Control of thermal effects. In: The Construction of Large Telescopes,
ed. D. L. Crawford, pp. 6~65. New York: Academic Press.
Statement of aims and limitations of the program. In: The Construc-
tion of Large Telescopes, ed. D. L. Crawford, pp. ~7. New York:
Academic Press.
With Bruce Rule. The Palomar 60-inch photometric telescope. Sky
Telesc., 32: 185-87.
1967
Future tools of the astronomer. (Darwin lecture.) Q. J. R. Astron.
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Astronomical optics. In: Annual Review of Astronomy and Astrophysics,
ed. Leo Goldberg, David Layzer, and John G. Phillips, vol.5, pp.
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IRA SPRAGUE BOWEN
119
1968
Comments on accuracy and on optical tests and adjustments of the
200-inch Hale Telescope. In: Symposium on Support and Testing of
Large Telescope Mirrors, pp. 8-9; 98-101. Tucson: Kitt Peak Na-
tional Observatory and Univ. of Arizona.
1969
With E. W. Denison and M. Schmidt. An image tube spectrograph
for the Hale 200-inch Telescope. In: Advances in Electronics and
Electron Physics, ed. L. Marton, vol. 28, pp. 767-71. New York:
Academic Press.
1972
National Geographic Society-Palomar Sky Atlas. In: National Geo-
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National Geographic: Wash.. D.C.
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