Brian Popp - Academia.edu (original) (raw)
Uploads
Papers by Brian Popp
American Journal of Physics, 1985
Towards the end of the eighteenth century it was discovered by Marc-Auguste Pictet of Geneva that... more Towards the end of the eighteenth century it was discovered by Marc-Auguste Pictet of Geneva that cold emanations from a flask of snow could be reflected and focused by mirrors in the same way as the emanations from a heated object. Pictet's discovery had an invigorating effect on research on radiant heat. We sketch the scientific milieu in which Pictet worked, describe the line of investigation that led him to his discovery, and summarize the theoretical explanations offered by Pictet and his contemporaries for this and related experiments. A simple qualitative explanation in modern terms is offered for the apparent radiation and reflection of cold. Finally, detailed directions are provided for replicating the experiment as a demonstration for the lecture hall. II. PICTET'S AND RELATED EXPERIMENTS WITH RADIANT HEAT, 1770-1804 A. Context of Pictet's experiment References to experiments with radiant heat appear in Italian, English, French, and German publications scattered over a period of 200 years, from 1570, say, to 1770. Knowledge of the single most basic phenomenon-the reflection and concentration of heat by curved mirrors-is, of course, a legacy of Greek antiquity: witness the story of the burning mirrors of Archimedes. Down to 1770, however, the experimentation was desultory and undirected.
American Journal of Physics, 1985
Towards the end of the eighteenth century it was discovered by Marc-Auguste Pictet of Geneva that... more Towards the end of the eighteenth century it was discovered by Marc-Auguste Pictet of Geneva that cold emanations from a flask of snow could be reflected and focused by mirrors in the same way as the emanations from a heated object. Pictet's discovery had an invigorating effect on research on radiant heat. We sketch the scientific milieu in which Pictet worked, describe the line of investigation that led him to his discovery, and summarize the theoretical explanations offered by Pictet and his contemporaries for this and related experiments. A simple qualitative explanation in modern terms is offered for the apparent radiation and reflection of cold. Finally, detailed directions are provided for replicating the experiment as a demonstration for the lecture hall. II. PICTET'S AND RELATED EXPERIMENTS WITH RADIANT HEAT, 1770-1804 A. Context of Pictet's experiment References to experiments with radiant heat appear in Italian, English, French, and German publications scattered over a period of 200 years, from 1570, say, to 1770. Knowledge of the single most basic phenomenon-the reflection and concentration of heat by curved mirrors-is, of course, a legacy of Greek antiquity: witness the story of the burning mirrors of Archimedes. Down to 1770, however, the experimentation was desultory and undirected.