 In 1820, an ill-fated expedition led by Dr Hamel included pigeons intended for release at varying altitudes to measure the impact of reduced air density on their ability to fly.In 1890, Joseph Vallot built a small meteorological observatory at approximately between the Dôme du Goûter and Mont Blanc's summit from where numerous measurements and scientific experiments were conducted.One study involved taking simultaneous temperature measurements made over many months at Chamonix, the Grands Mulets and at the observatory itself.