these Are The Lectures In Physics That I Gave Last Year And The Year Before To The Freshman And Sophomore Classes At Caltech. The Lectures Are, Of Course, Not Verbatim-they Have Been Edited, Sometimes Extensively And Sometimes Less So. The Lectures Form Only Part Of The Complete Course. The Whole Group Of 180 Students Gathered In A Big Lecture Room Twice A Week To Hear These Lectures And Then They Broke Up Into Small Groups Of 15 Or 20 Students In Recitation Sections Under The Guidance Of A Teaching Assistant. In Addition, There Was A Laboratory Session Once A Week.