252 



SCIENCE. 



[N. S. Vol. XXIV. No. 608. 



tember 5, and close on the following Saturday 

 morning. One course of five lectures will be 

 given by Professor E. H. Moore, of the Uni- 

 versity of Chicago, and two courses of four 

 lectures each by Professor Max Mason, of 

 Yale University, and Professor E. J. Wil- 

 czynski, of the University of California. Titles 

 and outlines of the courses are as follows: 



On the Theory of Bilinear Functional Opera- 

 tions: Professor E. H. Moore. 

 In the light of the general theory of dis- 

 tributive functional operations and with em- 

 phasis on various analogies between algebraic 

 and transcendental theories, the course is to 

 consider bilinear functional operations, in par- 

 ticular the theory and applications of linear 

 integral equations, as recently developed by 

 Yolterra, Fredholm, Hilbert and others. The 

 general point of view with references is to be 

 found in the article on fimctional operations 

 by Pincherle in the Encyclopedia, II A u- 



Selected Topics in the Theory of Boundary 

 Value ProMems of Differential Equations: 

 Professor Max Mason. 



The course will deal with the real solutions 

 of partial and ordinary linear differential 

 equations of the second order. The analytical 

 character of the solutions of partial differen- 

 tial equations of elliptic, parabolic and hyper- 

 bolic types will be discussed. Boundary value 

 problems for equations of these types and for 

 ordinary differential equations will be treated, 

 with special reference to the applications of 

 definite and indefinite integral equations and 

 of Green's functions. The relation between 

 boundary value problems and corresponding 

 problems in the calculus of variations will be 

 considered. Special reference will be made 

 to writings of Hilbert, Picard, Hadamard and 

 Bernstein, and to recent Gottingen disserta- 

 tions. The lectures will not assume a knowl- 

 edge of the theory of boundary value problems 

 or of calculus of variations. 



Projective Differential Geometry: Professor 



E. J. WiLCZYNSKI. 



Differential geometry has, heretofore, been 

 almost exclusively treated from the point of 

 view of the group of motions. In the present 



course, which is confined to plane and space 

 curves, and ruled surfaces, those properties 

 are investigated which depend upon the in- 

 finitesimal elements of the configuration con- 

 sidered but which are invariant under all 

 projective transformations. The references 

 will be principally to the work of Halphen 

 and that of the lecturer, which has been col- 

 lected in a treatise soon to be published by 

 B. G. Teubner under the same title as this 

 course. Some knowledge of the theory of 

 linear differential equations and of the theory 

 of continuous groups will be assumed. 



The morning lectures will begin at 10, the 

 afternoon lectures at 2 :30. Each lecture will 

 occupy an hour, and consecutive lectures will 

 be separated by an intermission. Two lec- 

 tures will be given on each morning, Wednes- 

 day to Saturday, inclusive, and on each of 

 two afternoons, and one lecture will be given 

 on Wednesday evening at 8. One afternoon 

 will be devoted to an outing. A charge of 

 three dollars will be made to those attending 

 any or all of these lectures. 



James Pierpont, 

 Percy E. Smith, 

 Heinrich Maschke, 

 H. S. White, 

 F. N. Cole, 

 Committee on Summer Meeting. 



SAMUEL LEWIS PENFIELD. 



Samuel Lewis Penfield, professor of min- 

 eralogy in the Sheffield Scientific School of 

 Yale University, died at South Woodstock, 

 Conn., on August 12, 1906, at the age of fifty 

 years. He has been continuously connected 

 with the Sheffield School since his graduation 

 from that institution in 1877. 



Professor Penfield, as a student, made a 

 specialty of analytical chemistry, and developed 

 wonderful ability in that line of work. Soon 

 after graduation he made many difficult 

 analyses of minerals, particularly of phos- 

 phates from Branchville. He studied organic 

 chemistry at Strasburg University in 1880- 

 81, but immediately afterwards he became in- 

 structor in mineralogy at New Haven, and 

 thenceforward devoted his whole attention to 



