Sleep Disorders
Cyclic alternating pattern
Nov. 11, 2023
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Miners extracting ore from a mine (4)
Engraving Dutch engraver Caspar Luyken (1672-1708) in Amsterdam, after a work by his father, Jan Luyken (1649-1712), 1694. A drum with a horizontal axis is being manually turned by a single person in the background with a poor mechanical advantage. A rope is wrapped around the drum so that one end lowers while the other end lifts. The amount lifted per load must have been quite small. In the midground, several miners are pushing carts with ore. In the foreground, a miner is examining the contents of an ore cart that has been emptied. A pickaxe is in the foreground on the left. (Courtesy of the Rijkmuseum, Amsterdam, The Netherlands. Public domain. Edited by Dr. Douglas J Lanska.)