Two men, in the hope of finishing early, and contrary to established Leadhills custom, had entered the mine before 4am; another two, presumably from the same partnership, entered soon after. Reaching their work level (at 25 fathoms) the first two encountered the bad air. They persisted, thinking they could force their way through it, began to feel dizzy, collapsed, and eventually suffocated. The next two encountered a similar fate. The accident was not discovered until some time after 6am; by which time all of the four men were dead.