Wilbur Olin Atwater
Wilbur Olin Atwater (1844-1907) was a pioneer in the study of nutrition, and many of his areas of research, including the nutritive value of foods, and the dietary and economic needs of low-income families, are still emphasized in USDA programs today.
His papers include early United States Department of Agriculture dietary guidance. The collection contains details of Atwater's study of the chemical composition of various foods, and his development and experiments with respiration calorimeters.
The photographs below show experiment subjects demonstrating the types of tasks performed within the calorimeter to study the energy expended during specific activities. The calorimeter consisted of a room, with arrangements for analyzing the composition of the incoming and outgoing air, in which a subject's carbon dioxide output is measured. A later modification also allowed measurement of oxygen uptake.