What do scientists mean when they call an experiment beautiful? An influential collection of essays entitled The Uses of Experiment finds no place to discuss experimental beauty.¹ Perhaps that is an appropriate omission. If we follow the dictionary definition of beauty, as "that quality . . . which affords keen pleasure to the senses . . . or which charms the intellectual faculties",² we may conclude that beauty does not belong within the category of utility. Does the beauty that scientists see in experiments, therefore, bear no relation to their pragmatic objectives? On the other hand, if, as one scientist has expressed it to me, "all important experiments are beautiful,"³ is beauty a functional attribute of the experiments that display it? Are there any more particular "indicators of beauty" shared by those experiments that scientists declare to be beautiful? Such questions are not frequently discussed by historians of science, and are, as the title of this volume implies, elusive. One way to begin to examine them is to focus our attention on specific historical examples of experiments that drew from contemporaries to whom it was pertinent the accolade "beautiful". I am presently engaged in writing a historical reconstruction of the origins of one such experiment.