The “crow’s nest” is an apparatus placed on the main top-mast, or top-gallant mast-head, as a kind of watch-tower for the use of the master or officer of the watch in the fishing-seas, for sheltering him from the wind, when engaged in piloting the ship through crowded ice, or for obtaining a more extensive view of the sea around when looking out for whales. When sailing among much drift-ice, as seen from the deck, it seems at a small distance impervious, although it may happen that scarcely any two pieces are connected; but from the mast-head, the relative position of almost every piece may be distinctly seen, and an opinion may be formed by the experienced observer of the probable and actual movements of such pieces as the ship is required to pass. This is an object of the greatest importance, because the varied movements of the different pieces occasion such an alteration in the channel pursued, that, were it not for a constant, attentive, and judicious watch by the master or an able officer, a ship would not pass through any crowded collection of drift-ice without the imminent risk of being stove. In difficult situations, a master’s presence at the mast-head is sometimes required for many hours in succession, when the temperature of the air is from 10° to 20° below the freezing point, or more. It is therefore necessary for the preservation of his health, as well as for his comfort, that he should be sheltered from the piercing gale. A piece of canvas tied round the head of the main top-mast, and heel of the top-gallant mast, extending only from the cap to the cross-trees, or at best, a canvas stretched round the base of the top-gallant rigging, but open on the after-part, was the most complete contrivance of a crow’s nest, until a few years ago my father invented an apparatus, having the appearance of a rostrum, which afforded an admirable defence against the wind. This contrivance, from the comfortable shelter it affords to the navigator, having come into very general use, it may not be improper to describe it more particularly.