Safety lamp could create a sufficient updraft that firedamp would not penetrate down the chimney. Further observations of the speed of flame fronts in fissures and passageways led him to design a lamp with fine tubes admitting the air. Sir Humphry Davy was asked to consider the problems of a safety lamp following the Felling explosion. Previous experimenters had used coal gas (chiefly carbon monoxide) incorrectly, believing it to be the same as firedamp. Davy however performed his experiments with samples of firedamp collected from pits. As an experimental chemist, he was familiar with flames not passing through gauze; his experiments enabled
Safety lamp to see where they were aiming (and accurate blows were needed), the eyes needed to be straining in what would normally be the upwards and slightly to one side direction. This straining led first to temporary nystagmus and then to a permanent disability. Mild nystagmus would self-correct if a miner ceased to perform this work but if left untreated would force a man to give up mining. The lower levels of light associated with safety lamps caused an increase in the incidence of nystagmus. Both on the continent of Europe and in the UK dried fish skins were used. From