Being keen to spend nights on the Vignemale, he bivouacked in the open - buried by his guides in a blanket of rocks and earth - on the summit of Pic Longue on 26 August 1880. It was at this point that he considered the installation of caves on the mountain, reasoning that any other construction would be unaesthetic and unwelcome. On his instructions, seven caves were built between 1881 and 1893.