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On the Discharge of Permanent Gases. J. ILLECK.

On Körting's Steam Jet Scrubber. B. KÖRTING

On the Manufacture of Gas from Paraffin Oils. L. GROTOWSKY.

On the Magnetic Constants of Nickel. M. WILD

New Mode of Duplex Transmission. O. MOREL
Proportions of Electro-Magnets. T. DU MONCEL

On a Common Law in Reference to Electric Induction. R. CLAUSIUS
The Dynamo- and Magneto-Electric Machines of the Lontin System
On the theory of Screw-propellers. C. SZILY

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line 6, for the sign of equality in the equation substitute the sign of
multiplication.

line 10, for "24 to 523 fathoms" read "167.6 to 36677 feet."

p. 280, line 18, for "xxii." read “xxiii.”

No. 1,511.—"Review of the Progress of Steam Shipping during the last Quarter of a Century." BY ALFRED HOLT, M. Inst. C.E.1 THE last five-and-twenty years have witnessed a revolution in the carrying trade of the world, and more particularly in that of this country, which only those who have been engaged in affairs connected with it can completely appreciate. It has been said that up to the moment of railways, an Englishman of the nineteenth century had no better mode of traversing the earth than a Roman of the time of Julius Cæsar, and up to the steamboat epoch, the same might with reasonable accuracy have been said for travel at sea; on neither element had the mode of travel changed, though it might have improved. There was, however, this marked difference between the application of steam to land carriage, and its application to water carriage, that whereas, in the former, its suitability to the conveyance of goods was at once recognised, and was indeed its original purpose, in the latter that use succeeded a long period during which it was applied only to the carriage of passengers and correspondence. The steam. navigation of the Atlantic began about 1838, and that of the Mediterranean at an earlier date; but till the period at which this review commences, twenty-five years ago, or 1852, in neither case was the old mode of conveyance for cargo by sailing vessel seriously invaded by the new. From that date a revolution has been witnessed, which has never, it is believed, received the attention it deserves. Broadly stated, and with some considerable exceptions, British carriage by sea has passed from the hands of sailing vessels to steamers. This extension was, in its early days, greatly encouraged by the lavish rates of freight paid by the English and French Governments for the charter of steamers during the Crimean war. At that time the capital embarked in a steamer was in many instances entirely repaid in twelve months, and this return naturally induced increased investments.

Three great changes of construction, from that which was accepted twenty-five years ago, have rendered possible the extension thus referred to. They are: (1) The screw propeller. (2) The iron vessel. (3) The compound engine. All were known, and the first and second were in moderate use, at the beginning of the time; but none had received that firm, unhesitating acceptance

1 The discussion upon this Paper occupied portions of four evenings, but an abstract of the whole is given consecutively.

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