## 4-22. Thomas Craig

Thomas Craig (1855–1900) was the son of immigrant Scots; his father worked as a mining engineer in the coal industry of Pennsylvania. He obtained a degree in civil engineering from Lafayette College in 1875, then taught mathematics in a high school in New Jersey, before winning a doctoral fellowship to study mathematics at the newly-opened Johns Hopkins University in 1876.

Craig successfully defended his thesis on “The representation of one surface upon another, and some points in the theory of the curvature of surfaces” in 1878, and joined the teaching staff of Johns Hopkins. He obtained a concurrent, part-time position with the Coast and Geodetic Survey, which he held until 1881. He then continued to teach mathematics at Johns Hopkins, along with James Joseph Sylvester, Arthur Cayley, and William Story; he also attended the lectures of Sylvester and Cayley.

Craig’s mathematical interests included elliptic functions and
differential geometry, topics on which he published in Crelle’s
*Journal*. Craig also published a treatise on
projections, and another on linear differential equations.

Craig served as associate editor of the Hopkins-published
*American Journal of Mathematics*, first under Sylvester, then,
upon the latter’s move to Oxford, under Simon
Newcomb. It is in this editorial capacity that
Craig came to exchange several dozens of letters with Poincaré, in the
period from 1883 to 1892. Craig’s interest in Poincaré’s work was not
purely editorial, however. He studied Poincaré’s papers, and found he
was not able to understand all of them to his satisfaction. This led
him to ask Poincaré for help, not by letter, but in person, after
steaming to Paris in June, 1884.

Thanks largely to Craig’s constant badgering, four papers by Poincaré
appeared in the *Journal*, along with a portrait (in 1889). Among
these is one of Poincaré’s most celebrated papers, describing the
“sweeping method”, or *méthode de balayage*, for solving the
Dirichlet problem (Poincaré, 1890). In fact, it was the latter paper
that Darboux and others advanced as meriting the 1910 Nobel Prize in
Physics in their letter of nomination.^{1}^{1}endnote:
^{1}
See Darboux et al. to
the Nobel Committee for Physics, ca. 1 January 1910
(§ 2-62-24).

Craig took over the editorship of the *American Journal of
Mathematics* from Newcomb in 1894, and was promoted to professor of
pure mathematics at Hopkins. In 1898, he relinquished the position of
editor due to ill health, and finally expired from heart failure at the age of 44
on 8 May, 1900.^{2}^{2}endnote:
^{2}
For biographical details, see
MacTutor,
and the obituaries
by Newcomb (1900), and Matz (1901).

## References

- Professor Thomas Craig, C.E., Ph.D.. American Mathematical Monthly 8 (10), pp. 183–187. Link Cited by: endnote 2.
- Professor Thomas Craig, Ph.D.. American Journal of Mathematics 22 (1), pp. v. Link Cited by: endnote 2.
- Sur les équations aux dérivées partielles de la physique mathématique. American Journal of Mathematics 12, pp. 211–294. Link Cited by: 4-22. Thomas Craig.