Briefly mentions pre-19th century ideas and discusses the contributions of Mohr, Seguin, Mayer, Grove, Colding, Joule and Helmholtz and the controversies regarding priority including Tyndall's involvement in one of them. Mentions the tension between philosophical and practical modes of thought in 19th century science. Includes portraits. (GH)

Describes thermonuclear processes induced by interaction of a laser beam with the surface of a fuel pellet. An expanding plasma is formed which results in compression of the element. Laser and reactor technology are discussed. Pictures and diagrams are included. (GH)

Describes construction of an inexpensive wind tunnel and a water manometer; experiments with model airplanes; and the calibration of the manometer and its use to measure wind velocity and lift on an airplane wing. Additional experiments with an electric fan are suggested. Diagrams are included. (GH)

A capacitor is discharged to generate an acoustical pulse and start a digital counter which is stopped by a microphone. Differences are accurately measured by positioning the sensing microphone on an optical bench. Results are discussed and extended experiments are suggested. The sources of some components are given. (GH)

Outlines the intellectual developmental stages described by Piaget. Advocates that instructional strategies avoid introducing abstract concepts before students have experience with concrete phenomena. (GS)

Presents an interview in which a dermatologist outlines the dangers of sunburn. Carcinogenic and aging effects are included. (GS)

Describes the major obstacles in the study of ultraviolet radiation (UV). Presents the beneficial aspects of UV such as vitamin O production, sterilization, clinical treatment of diseases and wounds, and the marking of patients for radiotherapy. Warns of the dangers of UV exposure such as skin cancer and early aging. (GS)

Recommends that teachers make use of the motivation that many young people devote to hobbies. Gives examples of this approach including the study of force, speed, work, power and various electrical concepts with model trains; acceleration and velocity with rocketry; focal length, magnification, field of view with astronomy and photography. (GS)