Born in Memphis, Tennessee, on 12 October 1883, Elmer Samuel Imes (figure 1) entered a nation that was still wounded from the Civil War—a war fought, at least in part, to determine whether people of his ethnicity could be the legal property of other people.1 Thirty-five years later Imes became only the second black man to receive a PhD in physics in the US.

Figure 1.

Elmer Samuel Imes (1883–1941). (Published by permission of Fisk University, John Hope and Aurelia E. Franklin Library, Special Collections; courtesy of the AIP Emilio Segrè Visual Archives.)

Figure 1.

Elmer Samuel Imes (1883–1941). (Published by permission of Fisk University, John Hope and Aurelia E. Franklin Library, Special Collections; courtesy of the AIP Emilio Segrè Visual Archives.)

Close modal

Imes first drew the attention of the scientific community as a graduate fellow at the University of Michigan, starting in 1915. There, under the direction of Harrison Randall, he performed experimental work focused on the precise measurement of the rotational–vibrational spectra of several diatomic molecules.2 Despite the quality of his scientific work, Imes’s professional path was far from easy, and his life and work give us important perspective on life for black scientists in the early 20th century.

Imes’s paternal grandparents, Samuel and Sarah Moore Imes, were a free black couple who farmed in south-central Pennsylvania.3 They were able to send their son Benjamin to Oberlin College in Ohio, where he earned a bachelor’s degree in 1877 and a divinity degree from the Oberlin Theological Seminary in 1880. While at Oberlin, Benjamin met his fellow student Elizabeth Wallace, who became his wife and mother to his three sons. Benjamin and Elizabeth became home missionaries in the Congregational Church and moved south to serve former slaves.

The three Imes sons would all prove to be high achievers. Elmer, the oldest, made his name in science; Albert became a successful businessman in the UK; and William became a renowned theologian and civil rights activist. By the early 20th century, the Imes family was widely known in educated and successful elite black communities.

After completing grammar school in Oberlin and high school in Normal, Alabama, Elmer Imes enrolled at Fisk University, an institution founded in 1866 in Nashville, Tennessee, primarily for the education of recently freed African Americans (see box 1). When Imes entered around 1899, Fisk was a relatively new institution of higher learning. Despite its youth, Fisk offered Imes a classical education superior to what was available to most African Americans at the time. He studied four languages—French, Greek, Latin, and Spanish—along with chemistry, biology, physics, and mathematics. He also took classes in English literature, ethics, sociology, and logic. Imes earned a bachelor of arts degree from Fisk in 1903 and then accepted a job teaching physics and mathematics at Albany Normal School in Albany, Georgia.

Box 1. Fisk University

A private historically black university in Nashville, Tennessee, Fisk University was founded in 1866 on a 40-acre tract of land just north of the city center. From its beginning, Fisk stressed high academic achievement. By the 1880s Fisk required that all students take courses in mathematics, science, and languages during each semester of their enrollment. That requirement reflected the fact that after graduation, many students would move to communities in which they might be the only university-educated black person; they would need to provide leadership on issues such as the purchasing and selling of property and guidance on setting up churches, medical clinics, and social services. They might also be called on to settle disputes between black people and often-oppressive white communities.

Fisk and several other black educational institutions faced a major dilemma at the start of the 20th century: What type of educational opportunities should be available to newly freed black people? The two individuals most identified with that debate were W. E. B. Du Bois of Massachusetts and Booker T. Washington of Virginia. Their philosophies and positions were determined in large measure by their radically different life experiences: Washington spent his childhood in slavery, which was not the case for Du Bois. Washington was a proponent of industrial training; he felt black people should learn useful trades and demonstrate their values to the nation. Du Bois, on the other hand, saw the need to develop a “talented tenth” who would serve two major purposes. First, through their intellectual achievements and related skills, they would provide leadership for the black masses. Second, those efforts would clearly demonstrate to white and black people alike the equal humanity of both communities.

Fisk offered students an education that was more in line with the Du Bois model than the Washington model. The university quickly assumed a central place in African American intellectual life. From the 1910s through the 1970s, Fisk was a haven for many black intellectual elites, particularly in the areas of physics, chemistry, music, art, writing, and black culture. It also provided a welcoming venue for the study of the meanings and consequences of the concept of race.

Measures of the overall quality of a great university include its graduates and its faculty members. The following is a selected listing for Fisk:

Graduates

W. E. B. Du Bois (1888)—sociologist, human rights activist, writer

John Hope Franklin (1935)—historian

David Levering Lewis (1956)—two-time Pulitzer Prize winner, historian

Nikki Giovanni (1967)—poet, writer

Judith Jamison (ca. 1970)—dancer and choreographer

Faculty

Arna Bontemps (1943–66)—head librarian; poet, writer

Percy L. Julian (1921–23)—chemistry professor; researcher, member of the National Academy of Sciences

Robert Hayden (1946–69)—English professor; US poet laureate

Aaron Douglas (1940–66)—art professor; painter, illustrator, muralist

Lee Lorch (1950–55)—mathematics professor; researcher, civil rights activist

Imes was determined to continue his education, but like many aspiring black scientists, he needed time to gather the money for further study. He also needed to support and care for his mother following his father’s death in 1908. After just over a decade of teaching, Imes earned a master’s degree in sociology at Fisk in 1915 and applied to the graduate program in physics at the University of Michigan, where he was accepted for probationary study. During the late 19th and early 20th centuries, it was common for northern universities to require black students graduating from black colleges to repeat the last year of the university’s undergraduate program because they felt they could not objectively measure the students’ qualifications. However, black students generally performed extremely well and after receiving their advance degrees were very successful in their careers.

That was certainly the case with Imes. After a year at Michigan he was chosen as a graduate fellow, a position he continued in until 1918, when he completed his doctorate. Imes was also one of the first African Americans to be initiated into Sigma Xi, a scientific honor society, and to be listed in American Men of Science, where he appeared in the sixth and several subsequent editions.

While at the University of Michigan, Imes was respected personally and professionally by faculty and fellow students. William Swann of the Bartol Research Foundation at the Franklin Institute in Swarthmore, Pennsylvania, later called his acquaintance with Imes during Imes’s graduate student years a privilege, and noted that “his research laboratory was a mecca for those who sought an atmosphere of calm and contentment.” Swann further recalled that “Imes could always be relied upon to bring to any discussion an atmosphere of philosophic soundness and levelheaded practicalness.”4 

Imes’s landmark work in physics included conducting the first high-precision experiments measuring the IR spectrum of three diatomic molecules: hydrogen chloride (HCl), hydrogen bromide (HBr), and hydrogen fluoride (HF). Those experiments provided verification that both the rotational and vibrational energy levels of molecules are quantized (see box 2). Through his detailed spectrum for HCl, Imes also gave the first direct evidence for the influence of different isotopes on the spectra of molecules.

Box 2. Diatomic Molecules

Diatomic molecules can vibrate along the line joining their atoms and rotate about an axis passing through the center of mass, perpendicular to the line joining the atoms (see also figure 2). However, quantum mechanics dictates that only discrete values exist for the associated vibrational and rotational energies. In the first approximation, we have for the vibrational–rotational energies

En,Jvr=Env+EJr

where Env is the vibrational energy and EJr is the rotational energy. They are given by the expressions

Env=hνn+12,EJr=h28π2µr02JJ+1,

where ν is the frequency of the vibration; µ is the reduced mass m1m2/m1+m2; r0 is the bond length between the atoms; h is Planck’s constant; and n and J are, respectively, the vibrational and rotational quantum numbers, taking the integer values (0, 1, 2, …).

The physically observed energy spectra are determined by the selection rules

n=±1,J=±1.

In general, +1 and −1 correspond, respectively, to absorption and emission processes.

Diatomic molecules can both vibrate along the bond length and rotate about their center of gravity (see figure 2). Classical physics predicted that the spectra of those combined phenomena should consist of three rather sharp lines in the IR region. However, early spectroscopic studies in the 19th century and the first 15 years of the 20th century showed unexpected “band spectra”—that is, very broad regions of absorption spread over two frequency intervals in the IR region.

Figure 2.

A diatomic molecule (a) can be represented classically as two masses, m1 and m1, connected by a spring. The equilibrium bond length is r0. (b) Vibrational motion takes place along the line connecting the two atoms. (c) The molecule can rotate around an axis passing through the molecule’s center of mass, perpendicular to the line joining the atoms.

Figure 2.

A diatomic molecule (a) can be represented classically as two masses, m1 and m1, connected by a spring. The equilibrium bond length is r0. (b) Vibrational motion takes place along the line connecting the two atoms. (c) The molecule can rotate around an axis passing through the molecule’s center of mass, perpendicular to the line joining the atoms.

Close modal

As the foundations of physics made the transformation from a classical to a quantum worldview, physicists developed theoretical explanations for the unexpected band spectra. Several prominent theorists and experimentalists of the early quantum era did at least a portion of their work on molecular band spectra. According to a detailed study by Chiyoko Fujisaki, before 1916 such individuals included experimentalists Eva von Bahr, Wilhelm Burmeister, and Heinrich Rubens and theorists Niels Bjerrum, Paul Ehrenfest, Edwin Kemble, Walther Nernst, and Lord Rayleigh.5 

Some of those individuals attended the Solvay Conference in Brussels, Belgium, from 30 October to 3 November 1911, the first in what would become a series of gatherings.6 It was sponsored by industrialist Ernest Solvay at the behest of Nernst to explore quanta and radiation. During his final talk of the conference, titled “The Current Status of the Specific Heat Problem,” Albert Einstein raised the issue of molecular spectra, which sparked a discussion about methods for quantizing the energy levels of molecules. Einstein’s previous work on the specific heat of solids had already paved the way toward acceptance of the idea that molecular vibrational energy must be quantized.

From 1911 through 1916, though, the data obtained from various experiments on molecular vibrational and rotational energy were confusing and in some cases contradictory. Some experiments showed broad bands; others gave results with bands resolved into a series of separated lines. In retrospect, the main reason for that confusion and contradiction was the differing resolutions of the spectrometers used by the various experimentalists. Physicists using what were later called “low resolution” devices observed two broad bands; those using “high resolution” devices observed more structure within the bands. By 1916 there was general agreement that high-precision spectra were needed for diatomic molecules in order to give both the detailed structure of the band spectra and the data needed to formulate an adequate theory to explain the spectra.

In 1916, under the direction of Randall at the University of Michigan, Imes began work that led to the design and construction of a series of IR spectrometers of continuously increasing resolving powers. Imes used his instruments to measure absorption bands in the near-IR region for three hydrogen halides: HCl, HBr, and HF.

Imes’s final spectrometer, used for his most precise work, actually consisted of two devices working in tandem. The first was a prism spectrometer, and the second was a grating spectrometer. His most detailed work was done for HCl (see figure 3). For that molecule, he found two absorption bands near 1.76 and 3.46 microns. His instrument was able to resolve the band at 3.46 microns into 12 pairs of peaks and the band at 1.76 microns into 8 pairs. The clear interpretation of his spectra was that peaks corresponding to transitions between quantized rotational energy states were superimposed on the spectral lines coming from the vibrational transitions of the diatomic molecules. Imes used the design and construction for the spectrometer and the data he measured as the basis for his doctoral dissertation. All of the results appeared in Astrophysical Journal2 in 1919.

Figure 3.

The spectra of hydrogen chloride published in Imes’s 1919 Astrophysical Journal paper.2 

Figure 3.

The spectra of hydrogen chloride published in Imes’s 1919 Astrophysical Journal paper.2 

Close modal

Imes’s measurements provided accurate experimental proof that rotational energy was quantized, and he was quickly recognized as a major figure among the small group of researchers focused on spectroscopy. In 1974 Earle Plyler, a US physicist and pioneer in the fields of IR spectroscopy and molecular spectroscopy, wrote that “up until the work of Imes, there was doubt about the universal applicability of the quantum theory to radiation in all parts of the electromagnetic spectrum. Some held it was useful only for atomic spectra (electronic spectra); some held that it was applicable for all electromagnetic radiation…. Imes’s work formed a turning point in the scientific thinking, making it clear that quantum theory was not just a novelty, useful in limited fields of physics, but of widespread and general application.”7 

German theorist Adolf Kratzer quickly demonstrated the importance of Imes’s work for the newly emerging quantum theory. He gave Imes’s spectra a detailed theoretical analysis using a quantum framework.8 Kratzer was able to calculate the bond lengths between the hydrogen and halogen atoms for three diatomic molecules—HCl, HBr, and HI—and obtained values consistent with previous estimates.

Another interesting and important feature in Imes and Randall’s data for HCl was that each of the 12 peaks within the band located at 3.46 microns were split into two peaks.9 That doublet substructure was soon given a compelling explanation by Kratzer and by F. Wheeler Loomis,10 who interpreted the phenomena as the consequence of chlorine having isotopes of mass numbers 35 and 37. Therefore H35Cl and H37Cl had slightly different positions for their rotational–vibrational spectra. Later in life, Imes would remark that “had he known even more physics at the time he might also have predicted the isotopy of chlorine from his 3.46µ HCl bond.”11 

Despite the excellence and impact of his work, as an African American Imes faced limited professional opportunities in most of the US during the early 20th century. New York City at the time stood out as a center for achievement among black intellectuals and artists, and Imes moved there in 1918. While working there, first as a self-employed consulting physicist and later as an employee of three engineering-based firms, Imes engaged in R&D work that led to four patents for devices or techniques for improving the measurement of magnetic properties of various materials.

In the years following World War I, New York City attracted black writers, artists, entertainers, political strategists, and intellectuals. In addition to producing innovative artistic work that in time would capture the world’s attention, members of what came to be known as the Harlem Renaissance discussed and wrote about the future of black people in America. In the 1920s such luminaries as Arna Bontemps, Aaron Douglas, Langston Hughes, W. E. B. Du Bois, Charles Johnson, and Walter White called Harlem home (see box 3). During his time in New York, Imes was intimately involved with that intellectual circle.

Box 3. The Harlem Renaissance

Black soldiers returning from World War I were often brutalized by white people and generally were not able to vote or participate fully in the political and social affairs of their communities. One response to that situation was the “New Negro Movement,” which had as its major goal the destruction of the negative images and stereotypes of black people held by most whites. One way to do that was to establish a culture based on authentic artistic, literary, and intellectual works by black people.

The movement, later called the Harlem Renaissance, was centered in the Harlem neighborhood in New York City; however, it also had strong representations in Chicago, Philadelphia, and Washington, DC. The basic premise of the movement was that cultural productions would prove the humanity of black communities and, consequently, allow black people to achieve political, social, and economic equality in the US. Some common themes of the Harlem Renaissance were black identity, the influence of slavery, and the effects of institutional racism. Since many consumers of Harlem Renaissance writing and art were members of the white cultural elite, the dilemmas associated with performing and writing for that audience also became a major theme.

The Harlem Renaissance helped to redefine how the US and the world understood black culture, and it had a major influence on many black writers in African and Caribbean European colonies. The movement was also a hotbed of political discussion and activism and set the stage for the civil and human rights movements of the 1940s to 1960s.

Some major players and leaders of the Harlem Renaissance included historian, journalist, and social critic W. E. B. Du Bois; philosopher, writer, and educator Alain Locke; and sociologist Charles Johnson. They all had earned doctoral degrees—from Harvard University, Oxford University, and the University of Chicago, respectively. Elmer Imes was also deeply engaged in the Harlem Renaissance. A member of one of the most distinguished black families in the US, he held a doctorate in physics from the University of Michigan, was keenly interested in the arts and literature, and was an avid reader. In addition, he married one of the movement’s leading writers, Nella Larsen.

Since most of the major participants of the Harlem Renaissance lived in the greater metropolitan New York area, they all knew and interacted with each other. When the movement ended, due primarily to the economic conditions arising from the Great Depression, many of its leaders and spokespeople landed positions at Fisk University. Their presence at that institution is one reason for Fisk’s prominence in the 20th century.

Among the figures in the Harlem Renaissance was writer Nella Larsen (figure 4), whom Imes met during his early years in the city. He shared her artistic and intellectual interests, and the two married on 3 May 1919. Larsen thrived in the Harlem Renaissance setting and published two novels, Quicksand (1928) and Passing (1929).

Figure 4.

Nella Larsen, circa 1928. (Courtesy of Beinecke Rare Book & Manuscript Library, Yale University.)

Figure 4.

Nella Larsen, circa 1928. (Courtesy of Beinecke Rare Book & Manuscript Library, Yale University.)

Close modal

By the end of the decade, Imes was eager to return to an academic environment. When he was offered the opportunity to develop a formal program of physics education and research at Fisk in 1930, he accepted (figure 5). His wife, however, had no interest in living in the racially segregated South and continued to spend most of her time in New York, where her friendships, professional relationships, and writing career flourished.12 

Figure 5.

Imes in his laboratory. (Published by permission of Fisk University, John Hope and Aurelia E. Franklin Library, Special Collections; courtesy of the AIP Emilio Segrè Visual Archives.)

Figure 5.

Imes in his laboratory. (Published by permission of Fisk University, John Hope and Aurelia E. Franklin Library, Special Collections; courtesy of the AIP Emilio Segrè Visual Archives.)

Close modal

In 1933 Larsen divorced Imes, claiming cruelty as the grounds for dissolving the marriage. It’s more likely that she was unwilling to leave New York, where she was part of a lively circle of artists and intellectuals, for the relatively tame life of a professor’s wife at a small liberal arts college. A scandal recounted in a front-page story in the 7 October 1933 issue of the Baltimore Afro-American suggested another reason the marriage ended. The article hinted that Imes was having an affair “with a white member of Fisk University’s administrative staff,” a rumor that was, in fact, true.12 

Imes was excited about the opportunity to elevate the physics department at Fisk by offering courses equal to the best available in bachelor’s and master’s programs at any university. He planned to have students involved in research even at the undergraduate level. Three of Fisk’s physics graduates in the class of 1935 were accepted into graduate programs at the University of Michigan. One, James Raymond Lawson, earned a doctorate; another, Lewis Clark, earned a master’s degree. The third student, Carolyn Parker, earned an MS in mathematics from Michigan in 1941 and an MS in physics from MIT in 1951.

Another of Imes’s goals as a Fisk faculty member—spurred perhaps by his years with the Harlem Renaissance—was to encourage consideration of how science intermingles with other disciplines. He developed a course, Cultural Physics, focusing on that topic. In an unpublished set of notes for the course, he jotted down an evocative passage from a 1934 article by physicist Wheeler Davey:

The study of mathematics and the fundamental sciences must form the backbone of the formal college curriculum of our ideal man. If he is to be a truly educated man, he must not only have culture, he must not only be a gentleman—he must also know the physical sciences and their applications…. And he will find too, that the sciences have a cultural value at least equal to that claimed for the classics and the humanities, for he will be able to see the greatest beauty ever revealed to man—the beauty of the forces of nature.13 

The world of art and cultural pursuits that Imes was part of in New York overlapped with his life at Fisk; he knew many on the Fisk faculty from associations formed in New York. For example, writer Bontemps and artist Douglas, prominent figures in the Harlem Renaissance, both joined the Fisk faculty. The Imes family name was well known among the elite, educated African American population, and Imes’s wife was widely known as a writer. Those associations were of great value in forming other connections at the university, particularly among faculty outside the sciences.

As his cultural-physics course would suggest, Imes’s interests went beyond the sciences. In addition to constructing a curriculum for the physics program, he was asked by the administration to help with the design of a new science building. That effort led to correspondence with other researchers, equipment designers, and manufacturers. Imes was also in charge of Fisk’s film equipment and used that knowledge to aid various university clubs. He was enthusiastically involved in Fisk’s annual Spring Arts Festival, an event that attracted internationally renowned artists and was popular in the larger Nashville community.

Imes was respected and highly regarded by both his students and others. A 1994 biography of Larsen14 described him as “an engaging man with old-world charm and courtly manners” (page 122). His former student Axel Hansen said that his mentor was “formal, very objective and very reserved, but he loved ladies; he would go to concerts in the Fisk chapel with a tuxedo on and in the company of a white woman” (page 396). Another Fisk student, Youra Qualls, called him “a wonderful fatherly figure, sophisticated, worldly-wise and [possessed of] a tenderness for young people” (page 397). A close Nashville associate, Isaiah Creswell, said, “No one impressed me more than Imes…. He liked sports, literature, arts, bridge and women…. Money meant nothing to him” (page 435).

Qualls eventually went on to earn a PhD from Radcliffe College and became a professor of English at Langston University in Oklahoma. Her recollection of her time at Fisk, sent to me in a letter dated April 1982, gives interesting insight into how Imes was viewed by his fellow molecular spectroscopy researchers. “I worked for Dr. Imes as secretary in either my junior or my senior year in college,” Qualls wrote. “At the time Dr. Imes was writing a history of physics. One of the delightful tasks I assumed was going through foreign science journals to note references to the work of ‘Imes of the U.S.A.’” That work left her with the impression that “Dr. Imes was, I believe, far better known abroad than he was in his own country.”

A later incident reinforced that impression. “I was teaching at Langston University in the year that Dr. Charles S. Johnson became Fisk’s president,” Qualls recalled. “On my way to Fisk for the inauguration, I met a Dr. Nielsen, Dean of the Graduate School of Sciences at the University of Oklahoma. As Dr. Nielsen and I talked, Dr. Imes’s name came into the conversation. He told me that he had become familiar with the work of ‘Imes of the U.S.A.’ during his student days in Denmark but that he had never known that Imes was a Negro.”

Detail from Black Belt (1934), Archibald J. Motley Jr, noted Harlem Renaissance painter. (Hampton University Museum, Hampton, VA/© Valerie Gerrard Browne/Chicago History Museum/Bridgeman Images.)

Detail from Black Belt (1934), Archibald J. Motley Jr, noted Harlem Renaissance painter. (Hampton University Museum, Hampton, VA/© Valerie Gerrard Browne/Chicago History Museum/Bridgeman Images.)

Close modal

On the afternoon of 11 September 1941, Imes died of throat cancer at Memorial Hospital in New York City. All the arrangements were handled by his brother, William, reverend of St James Presbyterian Church, New York City. Two days later his body was cremated. His ashes were later taken to Nashville and scattered around a rose bush at his former home at Fisk University.

Two official professional obituaries were published. The first, in Science, was by his longtime friend and colleague Swann, who wrote that “science loses a valuable physicist, an inspiring personality and a man cultured in many fields…. In his passing, his many friends mourn the loss of a distinguished scholar and a fine gentleman.”4 

The second obituary was written by Alfred Martin, an instructor under Imes at Fisk University, and was published in the American Journal of Physics. “With his passing future generations of physics students have lost the privilege of studying under a truly masterful teacher; his colleagues, an esteemed counsellor; and his family and friends, a devoted companion,” Martin lamented. “The genius of the man for inspiring his students and his associates will cause his memory to linger long in the hearts of many.”11 

Those obituaries make it clear that Imes’s legacy was not only contained in his groundbreaking scientific papers. His wide-ranging interests were a splendid match with the rich intellectual environment at Fisk, and his dedicated mentorship opened doors for his students. As an accomplished scientist, a skilled teacher, and a cultured, well-rounded thinker, Imes stands as an example of a true renaissance man.

For teaching resources about Elmer Samuel Imes, readers can download two free lesson plans from the American Institute of Physics Center for the History of Physics. The first plan focuses on his work in spectroscopy; the second explores his connection to a 1930s civil rights case that sparked nationwide protests.

This essay is adapted and expanded from my article “Imes, Elmer Samuel” in the Complete Dictionary of Scientific Biography (2008).

1.
B. H.
Reid
,
The Origins of the American Civil War
,
Routledge
(
1996
).
2.
E. S.
Imes
,
Astrophys. J.
50
,
251
(
1919
).
3.
W. L.
Imes
,
The Black Pastures: An American Pilgrimage in Two Centuries—Essays and Sermons
,
Hemphill Press
(
1957
), chaps. 1 and 2.
5.
C.
Fujisaki
,
Hist. Sci.
24
,
53
(
1983
);
C.
Fujisaki
,
Hist. Sci.
25
,
57
(
1983
).
7.
N.
Fuson
, notes taken 16 August
1974
on a talk by
E.
Plyler
, Special Collections, John Hope and Aurelia E. Franklin Library, Fisk University, Nashville, TN.
9.
H. M.
Randall
,
E. S.
Imes
,
Phys. Rev.
15
,
126
(
1920
), p. 152.
10.
F. W.
Loomis
,
Astrophys. J.
52
,
248
(
1920
).
11.
12.
G.
Hutchinson
,
In Search of Nella Larsen: A Biography of the Color Line
,
Harvard U. Press
(
2006
).
13.
E. S.
Imes
, personal notes, box 2, folder 21, Elmer S. Imes Collection, 1902–1942, Special Collections, John Hope and Aurelia E. Franklin Library, Fisk University, Nashville, TN;
14.
T. M.
Davis
,
Nella Larsen, Novelist of the Harlem Renaissance: A Woman’s Life Unveiled
,
Louisiana State U. Press
(
1994
).

Ronald E. Mickens is the Distinguished Fuller E. Callaway Professor of Physics at Clark Atlanta University in Atlanta, Georgia.