786 SCHOOL SCIENCE AND MATHEMATICS

MISSOURI SOCIETYThe program of the Mathematics Section of the Missouri State Teachers

Association to be given in St. Louis, Mo., at the regular annual meetingearly in November:The Future of Mathematical Education, by Professor Chas. N. Moore,

of the University of Cincinnati.Mathematics from the Standpoint of the Junior College, by Miss

Leolian Carter of the Central High School, St. Joseph, Mo.Mathematics from the Standpoint of the Junior High School, by

Principal H. H. Ryan of the Ben Blewett Junior High School, St. Louis,Mo.The National Committee on Mathematical Requirements, and the

National Council of Teachers of Mathematics, by Dr. Eula A. Weeks,of the Cleveland High School, St. Louis.

Professor Moore will also address the Secondary Section of the Asso-ciation on, What a High School Graduate Ought to Know. ProfessorMoore is a member of the National Committee on Mathematical Require-ments. The Missouri teachers are very fortunate in having this oppor-tunity of hearing him.

ALFRED DAVIS,President of the Mathematic Section.

STEREOSCOPIC PROJECTION.At the meeting of the French Photographic Society, held on April 22

last, says L. P. Clere writing in The British Journal, a very interestingexperiment in stereoscopic projection was made by M. Maurice Miet.He used a positive transparency made from the ordinary stereoscopicnegative without the usual transposition. The image to be viewed by theleft eye was projected on the right of the screen, and that to be viewedby the right eye, to the left. Stereoscopic viewing was obtained bycrossing the directions of the ocular axis, namely, by looking at an objectheld for an instant at a short distance from the eyes. The new feature,in this experiment of M. Miet’s, consisted in using, as this object, a cardin which a square aperture was cut. A card of about half-plate size,with a square hole about two by two inches, serves well when held in frontof the eyes at about l-20th of the distance of the eyes from the projection-screen. Although this mask cuts off the two side images, which, in thismode of viewing usually enclose the central stereoscopic image formedby the superimposition of the two component images, it reduces consider-ably the strain of observation, and avoids the sudden separation of thesuperimposed images which readily takes place when this simple accessoryis not used. The effect of relief produced in this way is positively striking;but is seen only by persons who have acquired the ability to see stereo-scopically without a stereoscope. Moreover, it imposes a strain on themuscles of the eyes, as does the use of ah improperly adjusted stereoscope.The members of the audience who, in these circumstances, saw the stero-scopic effect, were asked to raise their hands and were found to be in aminority. But there is no need to resort to projection in order to ascer-tain the absence of the power of seeing steroscopically of the manypeople who prefer to close one eye when asked to look into a stereoscope.The process is so simple that it can easily be experimented with, and itsrepetition would interest many photographic societies so long as theexercise is limited to not more than a dozen views on the screen, so thatthere may be no excessive strain of the eyes.�Photo Era.