A successor to the author's Mr. Tompkins in Wonderland (1940), and more sharply limited in scope and appeal to students of physics, particularly to students interested in atomic structure. It is written, in part, around a Mr. Tompkins, son-in-law of a professor in physics whose discourses on atoms, electrons, neutrons, positrons and the like send the layman Tompkins into deep slumber. During his naps he dreams graphic dreams in which electrons are as large as he, able to talk and explain themselves, or else they appear the size of baseballs which professorial characters can manipulate in explanation of their functions. Much of what atoms consist of and how they work are thus made comprehensible to many a lay mind, although the subject is unfamiliar enough to the average reader to demand some basic conception of physics. The four lectures which put Mr. Tompkins to sleep are appended to the book, and contain much variegated and energetic impact for the reader. Considering the difficulties of its scientific thesis, the literary style is easy, and the humor refreshing.