In 1838, Agassiz founded a lithographic printing establishment in Neuchâtel, where his work could be done under his own direction instead of in Munich. He was now, besides his duties as professor, at work on "Living and Fossil Echinoderms and Mollusks," as well as "Fresh-Water and Fossil Fishes," and soon after upon the "Études sur les Glaciers," with an atlas of thirty-two plates. The book gave an account of all previous glacial study, and the observations of himself and companions. "Agassiz displayed during these years," said one of his co-workers, "an incredible energy, of which the history of science offers, perhaps, no other example." He worked always till midnight, often till two or three o'clock, sitting for hours at his microscope, troubled much with congestion of the head and eyes. The expense involved in his work was enormous, and he was burdening himself with debts, which are more wearing and destructive to health and happiness than any amount of work can ever be. Still he struggled on, through these dark days of poverty. He was only thirty-three, so young-looking that, on seeing him, people asked if he were "the son of the celebrated professor of Neuchâtel." He had already been chosen a member of the Royal Society of London. In 1840 he made his first permanent station on the Alps, taking with him barometers, thermometers, hygrometers, psychometers, boring apparatus, and microscopes, making the Hospice of the Grimsel his base of supplies, and the lower Aar glacier the scene of his work. A huge boulder, its upper surface forming a roof, with a stone wall constructed on one side, became the sleeping-room of Agassiz and five friends. This abode was called the Hôtel des Neuchâtelois. Jacob Leuthold, an intrepid Swiss, was their chief guide. He died at thirty-seven, sincerely mourned by all. They made dangerous ascents of snow-covered peaks, measured the depth and forward movement of glaciers, Agassiz even being lowered by ropes one hundred and twenty-five feet into a glacial well, to investigate its formation. All Europe was becoming interested in glaciers. Edward Forbes wrote from Edinburgh: "You have made all the geologists glacier-mad here, and they are turning Great Britain into an ice-house." Darwin was deeply interested. He wrote from North Wales: "The valley about here and the site of the inn at which I am now writing must once have been covered by at least eight hundred or one thousand feet in thickness of solid ice! Eleven years ago I spent a whole day in the valley where yesterday everything but the ice of the glaciers was palpably clear to me, and I then saw nothing but plain water and bare rock."