“Lewis and Clark kept 18 of what Jefferson called their “traveling pocket journals;” 13 were larger notebooks bound in red morocco leather, 4 were smaller and bound in paper board, and one was Clark’s field notebook bound in elkskin. Clark carried this elkskin field book during times of inclement weather or while canoeing down a river in order not to risk damage to one of the larger red notebooks. He would then copy his field notes into the red notebooks later on. When all the notebooks were not in use they were kept protected in tin cases. When their pages had been completely filled, the notebooks were sealed safely shut inside the cases for a safe return to Washington.”

— The Pocket Notebooks of 20 Famous Men