The sailor is more likely to be given to what we now term superstitions than say the weaver, because his activity is more at the mercy of sudden change and unforeseen occurrence. But even the sailor while he may regard the wind as the uncontrollable expression of the caprice of a great spirit, will still have to become acquainted with some purely mechanical principles of adjustment of boat, sails and oar to the wind. Fire may be conceived as a supernatural dragon because some time or other a swift, bright and devouring flame called before the mind's eye the quick-moving and dangerous serpent. But the housewife who tends the fire and the pots wherein food cooks will still be compelled to observe certain mechanical facts of draft and replenishment, and passage from wood to ash.