Eunice Newton Foote experimentally demonstrated that carbon dioxide retains more heat than common air when exposed to sunlight. Her experiments with glass cylinders and different gases, presented at the AAAS in 1856, constitute the first documented observation of what we today call the greenhouse effect. John Tyndall published more precise measurements in 1859 without citing Foote. She could not present her own work: Joseph Henry read it on her behalf because women had no access to the AAAS podium.