Page:The Development of Navies During the Last Half-Century.djvu/285

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Steam Propulsion.
241

steamers on the Atlantic the weight of machinery per indicated horse power is about 280 lbs.' This shows, says the Liverpool Journal of Commerce, how impossible it is to institute comparisons between a merchant vessel and a warship. The question is constantly asked by outsiders why it is that the ships of the Royal Navy cannot make passages equal to those achieved every day by the Atlantic 'greyhounds.' The answer is that they are not built for it. In, say, the 'Teutonic' the propelling machinery is made the great consideration. Everything is, and can be without harm, sacrificed to it. But it is far different in a man-of-war. As was long ago remarked, a fighting ship must always be a compromise. There are three great requisites: offensive power, meaning guns and torpedoes; defensive power, meaning armour, whether applied to sides, turrets, barbettes, or decks; and speed, meaning the most powerful engines, combined with the greatest coal endurance, that it is possible to get a ship of given tonnage to carry. If the tonnage is a fixed quantity, every attempt at extension in the direction of any of these three qualities can only be made at the expense of the other two. Hence the craze for inordinate lightness of machinery.

As the very latest development of extreme steam power, with the view of giving to a warship unprecedented speed, attention must be called to the as yet uncompleted cruisers 'Blake' and 'Blenheim,' engined respectively by Messrs Maudslay and Messrs Humphrys. It is probable that there will be but little difference between them, as far as steaming capabilities are con-