geometer

One of the most often cited books in the subject of triangle geometry is Roger A. Johnson's Modern Geometry - An Elementary Treatise on the Geometry of the Triangle and the Circle (Houghton Mifflin, 1929).
Born in Gardner, Massachusetts, Roger A. Johnson received his Ph.D. from Harvard in 1913, having written his dissertation, "An Analytic Treatment of the Conic as an Element of Space of Three Dimensions," under the direction of J. L. Coolidge. In 1926 he joined the mathematics department of the Brooklyn branch of Hunter College, which later became Brooklyn College. He served as chairman of the department from 1947 until retiring in 1952. |

Following is a list of Johnson's articles in journals in the *American Mathematical Monthly:*

23 (1916) 61 Relating to the "Simson line" or "Wallace line"

23 (1916) 161 A circle theorem

24 (1917) 101-105 Directed angles in triangle geometry

24 (1917) 243 Relating to a problem in minima ...

24 (1917) 313-316 Directed angles and inversion, with a proof of Schoute's theorem

25 (1918) 108-112 The theory of similar figures

27 (1920) 312-315 Determination of an angle of a right triangle, without tables

30 (1923) 250-251 On the circles of antisimilitude of the circles determined by four given points

34 (1927) 429-452 On the approximate division of the circle

35 (1928) 187-188 A problem in maxima and minima

37 (1930) 188-211 The arc of the ellipse

52 (1945) 208 A note on areas

54 (1947) 410-442 Linear differential equations

54 (1947) 594-595 An ornithological note

Johnson's dissertation served as a basis for his publication, "The Conic as a Space Element," in *Transactions of the American Mathematical Society* (1914) 335-368.

Photograph courtesy of the Department of Mathematics, Brooklyn College.