Philosophical Portrait Series. No. 100. 43 portraits on plate paper, $6.25 per set net. No. 100a. 43 portraits on Japanese vellum, $8.75 per set net. Single portraits on American plate, 25c net. Single portraits on Japanese vellum, 35c net. Psychological Portrait Series. No. 101. 25 portraits on plate paper, $3.75 net. No. 101a. 25 portraits on Japanese vellum, $5.00 net. Single portraits on American plate, 25c net. Single portraits on Japanese vellum, 35c net. Framing Portrait of Hugo de Vries. Platino finish. 10" × 12", unmounted, $1.00 net. Framing Portrait of William James. Printed on Japan paper. 11" × 14", $1.00. Portraits of Eminent Mathematicians Three portfolios edited by David Eugene Smith, Professor of Mathematics in Teachers' College, Columbia University, New York. In response to a widespread demand from those interested in mathematics and the history of education, Professor Smith has edited three portfolios of the portraits of some of the most eminent of the world's contributors to the mathematical sciences. Accompanying each portrait is a brief biographical sketch, with occasional notes of interest concerning the artist represented. The pictures are of a size that allows for framing (11" × 14"), it being the hope that a new interest in mathematics may be aroused through the decoration of classrooms by the portraits of those who helped to create the science. Portfolio No. 1.--Twelve great mathematicians down to 1700 A.D.: Thales, Pythagorus, Euclid, Archimedes, Leonardo of Pisa, Cardan, Vieta, Napier, Descartes, Fermat, Newton, Leibniz. Portfolio No. 2.--The most eminent founders and promotors of the infinitesimal calculus: Cavallieri, Johann and Jakob Bernoulli, Pascal, L'Hopital, Barrow, Laplace, Lagrange, Euler, Gauss, Monge, and Niccolo Tartaglia. Portfolio No. 3--Eight portraits selected from the two former portfolios, especially adapted for high schools and academies, comprising portraits of Thales--with whom began the study of scientific geometry; Pythagoras--who proved the proposition of the square on the hypotenuse; Euclid--whose Elements of Geometry form the basis of all modern text-books; Archimedes--whose treatment of the circle, cone, cylinder and sphere influences our work today; Descartes--to whom we are indebted for the graphic algebra in our high schools; Newton--who generalized the binomial theorem and invented the calculus; Napier--who invented logarithms and contributed to trigonometry; Pascal--who discovered the "Mystic Hexagram" at the age of sixteen. Portraits of Mathematicians, Part I. No. 102. 12 portraits on American plate paper, $3.00 net. No. 102a. 12 portraits on Japanese vellum, $5.00 net. Single portraits, American plate, 35c net. Single portraits, Japanese vellum, 50c net. Portraits of Mathematicians, Part II.