The Chair That Would Not Let Him Eat

Santorio Santorio held the chair of theoretical medicine at Padua from 1611, corresponded with Galileo, invented a working thermometer around the same time as Galileo, and is now regarded as the founder of quantitative physiology. He weighed things for a living. Then he decided to weigh himself.

For the next thirty years, he did almost nothing else.

He built a chair in his Venice dining room and hung it from a Roman steelyard balance concealed above the ceiling. He ate in it. He slept in it. He weighed himself before and after urinating, defecating, and, by his own accounting, sex. When word got around that a Venetian physician was weighing his own feces on a scale, a rival physician published a formal attack in 1615, and Santorio wrote a formal rebuttal explaining, patiently, that he calculated the weight by subtraction.

The chair was rigged. Once he had eaten his predetermined ration, his own increased weight lowered the seat until the dining table drifted quietly out of reach.

He filled some ten thousand entries this way. From them he deduced that a human being loses roughly half a pound a day through the skin and the breath, invisibly, into the room.

He was right. He had built a machine that took the food away from him, and inside it he discovered that we are all evaporating.