inventors, of course, are able to point to other advantages possessed by these ventilators, but the above are the salient features, which have won for their system marked recognition and pretty wide adoption. As evidencing its efficiency, it may be stated that Messrs Boyle’s system was awarded the “Burt” prize of £50, offered for international competition by the Shipwrights’ Coy. of London in 1882 for the best system of ship ventilation. Having regard to the great importance of first providing means whereby foul air may be extracted from compartments rather than first attempting to put fresh air in—at least by other than mechanical means—it has become the practice with several steamship companies to fit a series of pipes from the rooms throughout the ’tween decks all leading into a common main, carrying this main into the boiler funnel, and thus utilising the powerful draught existing there when the vessel is under way. The efficiency of this method is all that could be wished, but its action is necessarily impaired when the vessel is in port and the boilers not in use. For steamships having long runs its value is very considerable; but in steamers having short passages and long port delays its merits are not so pronounced, and it is, of course, of no account when sailing ships are concerned. Two systems of ventilation much alike in principle and equally applicable to the steamer and sailing ship may be shortly referred to. One is the Norton Ventilator, in which the dipping motion of vessels is utilised in effecting their own ventilation; the action in ocean-going vessels, of course, being continuous and automatic. Two cylinders, closed at the upper ends, are placed on each side of the stern post at such a distance as not to interfere in any way with the action of the rudder, and sufficiently close under the stern to be well out of harm’s way. As the vessel rises the water drops in these cylinders, which are partly submerged, and in its fall causes a vacuum, to fill which the air is drawn from all parts of the ship. The sinking motion of the vessel again fills the cylinders and forces the foul air collected, through the discharge pipes. The ventilator admits also of being actuated by steam or other power on board steamships, the exhausting and forcing device in this case consisting of a water bell or air chamber to which a vertical reciprocating motion is imparted by a beam or other attachment operated upon by the mechanical power adopted. The other method referred to is that now being pretty extensively introduced by Messrs Mosses and Mitchell, of London. It consists of two small cylinders, placed on either side of a ship, in-board, and connected by a pipe. The cylinders are partly filled with water, and, as the vessel rolls, the water rushes from the elevated to the depressed side of the ship, from one cylinder to the other, and, by creating a vacuum, draws up the foul air from between decks, or out of the hold, by pipes leading below.