rise to greater controversies than the proper method of disposing the armour. On the whole the system adopted in 1889 has given general satisfaction. It involves large proportionate weights and costs. On a ship like the Royal Sovereign the thick vertical armour weighs about 3000 tons, and costs over a quarter of a million sterling. Great improvements in armour have been made in recent years, increasing its defensive power for a given thickness and weight. But in view of remarkable developments in explosives and ordnance there is no disposition to diminish weights of armour on battle-ships. In fact increased protection to secondary armaments involves greater weights in proportion to displacements. Since modern war-ships have higher speeds, greater coal supplies, more powerful armaments, and better protection, it is inevitable that they should be of greater size and cost than their predecessors. In the mercantile marine, also, the demands for higher speeds or greater carrying power have involved considerable enlargement of dimensions and additional first cost. The largest passenger and cargo steamers, as a matter of fact, exceed in dimensions and displacements the largest battle-ships and cruisers. Their costs are less than those of the war-ships, because they are much less elaborately fitted and carry no armaments. On the Trans-Atlantic service there are employed passenger steamers from 525 to 600 feet in length, and from 15,000 to 20,000 tons displacement. The largest battle-ships yet laid down for the Royal Navy-the Majestic classare 390 feet long and of 14,900 tons displacement. The largest cruisers the Powerful class-are 500 feet long and of 14,200 tons displacement. Analysing the designs of war-ships, and comparing them with merchant ships-as far as comparisons are reasonable between vessels built for entirely different services-one is forced to the conclusion that the sizes and cost of recent war-ships are relatively moderate. If size and cost are to be reduced, as some persons strongly urge, then it will be absolutely necessary to reduce some or all of the qualities associated in the designs of the large ships; to accept lighter guns, less weight of protection, lower speeds, or lessened coal supplies. In other words, to produce fighting machines of smaller individual power, comparing badly with the ships of most recent design built or building abroad. There would be no difficulty, of course, in producing a larger number of less powerful ships for a given expenditure. But it would be a new departure in British naval policy to deliberately accept individual inferiority in our ships to foreign ships for the purpose of securing greater numbers. If the necessary expenditure is faced, superiority in numbers as well as in the powers of individual ships can be secured; and the weight of public and professional opinion undoubtedly inclines to that side. If the constitution of the Naval Defence fleet is considered, it will be noted that only the ten battle-ships are really of large dimensions, out of the total number, seventy. This is an illustration of general practice, although the advocates of moderate dimensions frequently proceed on the hypothesis that only large ships are built. As a matter of interest the ships built or building from my designs, since I took office in 1885, have been classified. Out of a total of 131 ships, only 15 are above 10,000 tons in displacement, 12 from 7000 to 9000 tons, 46 from 2500 to 5600 tons, 11 from 1000 to 2500 tons, and 47 are 1000 tons or under. War-ship dimensions and cost are not to be regulated by arbitrarily chosen limits. The proper procedure is obviously to decide what qualities shall be possessed by each type, and to produce ships possessing those qualities. No better guide under existing circumstances, and apart from actual experience in naval warfare, can be found than in making provision for meeting the possible attacks of foreign fleets, and securing superiority in numbers and in fighting efficiency in each class. Since British ships are built for operating on an enemy's coast, it is the practice to give them larger coal supplies, more stores, equipment and ammunition. Hence they are, class for class, of larger displacement than foreign ships. They are not, however, of greater cost than foreign ships of less displacement. A Royal Sovereign can be produced in a Government dockyard for a net cost, excluding armament, of about 760,000l. The corresponding cost for a French, Russian or American battle-ship of the first class is from 900,000l. to 1,000,000l. Consequently in the matter of money value risked on each ship we have a distinct advantage, thanks to our more economical construction. Taking armament and stores into account, one of the larger battle-ships in the Naval Defence fleet represents in round figures a million sterling when equipped for sea. It is a great responsibility to command such a costly and complicated fighting machine. Naval officers have, however, risen to the occasion, as it is their habit to do. As regards manageability and manoeuvring power, the big ships have proved most satisfactory, being as thoroughly under command as much smaller ships. It is a very striking thing to see one or two men steering a ship of 14,000 tons moving at high speed, with the aid of a steam or hydraulic engine. The huge mass answers every motion of the helm, and can be made to reverse its course at full speed in 3 to 3 minutes, and in a path whose diameter is about five times the ship's length. A modern fleet requires large expenditure for its construction and equipment. The seventy ships of the Naval Defence Programme will cost about 223 millions, including armaments. Excluding armaments, ammunition and reserves, the cost has been about 18 millions, or an average cost per ship of more than a quarter of a million sterling. This average cost exceeds the cost of the largest unarmoured screw three-deckers, carrying 121 guns, which were the most powerful ships in the Royal Navy thirty-five years ago. It is more than double the cost of the largest sailing three-deckers built about eighty years ago. What has been said above furnishes the explanation of this remarkable increase in outlay on modern ships. The range of net cost in the dockyard-built ships is from about 780,000l. for a first class battle-ship down to 50,000l. for a torpedo gunboat. Allowing for alterations in designs, changes in the rates of wages to dockyard workmen, and variations in systems of accounts that have been made since the scheme was first framed, there has been a remarkably close agreement between the original estimate and the actual outlay. That estimate was 21 millions, the probable expenditure 223 millions, and specific causes of increased cost represent about one million. There are few engineering works of great magnitude where the agreement between estimate and expenditure has been so close. The work of construction has been divided between the Royal Dockyards and private firms. Ten millions represent the value of the contract ships and their armaments; 123 millions the corresponding outlay on and for the Dockyard ships. As a matter of fact, the real expenditure in the Dockyards has been on labour, representing about 3 millions. Materials, machinery, guns, gun-mountings and other items of equipment have been made outside the Dockyards. These figures indicate how large an employment of the manufacturing and industrial resources of the country has been involved in carrying out a programme which adds greatly to our naval strength. It is the more remarkable that the programme should have been practically carried through as proposed, when it is remembered that the five years over which it has extended have been years of unprecedented activity in merchant ship construction. No better proof could be given of the surpassing resources of this country for shipbuilding and engineering. The great requirements in guns and gunmountings have also been met with ease. One incidental result of the Naval Defence Act which deserves mention is the enlargement of our resources for the manufacture of ordnance, many eminent firms having undertaken and satisfactorily executed important contracts, and the guns having been ready in time for the ships. A necessary condition of rapid construction is, of course, thorough prevision and pre-arrangement in all departments, so that there shall be no hindrance of work while waiting for portions of armament or equipment. Rapid construction also means ample financial provision, adjusted to the greatest rate of progress obtainable. Unless such provision is made the work must linger on, and progress will be regulated by the means available. In this brief summary of what is involved in making a modern fleet, it has been impossible to dwell upon the many difficulties that have to be met in connection with war-ship designs. War-ships are primarily fighting machines. Fighting efficiency dominates their designs, and more particularly the arrangements laid down as necessary for armaments and protection. Every cubic foot of internal space has to be appropriated to and fitted for some special purpose. Accepting these fixed conditions, the endeavour of naval architects is to fulfil them in ships which shall be strong, stable and sea-worthy, possessing the speeds and coal-supplies specified for various types. If complete success is not attained in all cases it should be remembered that the problems which have to be solved, are of increasing difficulty and complexity. And, on the whole, it may be claimed that the designers of modern war-ships, with the aid of their collaborateurs-marine and mechanical engineers, electricians, artillerists and metallurgists-have achieved remarkable results. Speeds have been greatly increased, offensive and defensive powers developed, and sea-keeping qualities maintained. Those who have to design and build war-ships, as well as those who have to fight them, may be pardoned if they sometimes wish that earlier and simpler conditions had continued. But the progress of invention and the constant struggle for maritime supremacy demand continuous effort, in order that Her Majesty's ships shall in no senso be inferior to those produced in other countries. [W. H. W.] WEEKLY EVENING MEETING, Friday, March 16, 1894. The RIGHT HON. EARL PERCY, F.S.A. Vice-President, The RIGHT HON. LORD RAYLEIGH, M.A. D.C.L. LL.D. F.R.S. M.R.I. PROFESSOR OF NATURAL PHILOSOPHY, R.L. The Scientific Work of Tyndall. It is fitting that the present season should not pass without a reference on these evenings to the work of him whose tragic death a few months since was felt as a personal grief and loss by every member of the Royal Institution. With much diffidence I have undertaken the task to-night, wishing that it had fallen to one better qualified by long and intimate acquaintance to do justice to the theme. For Tyndall was a personality of exceeding interest. He exercised an often magical charm upon those with whom he was closely associated, but when his opposition was aroused he showed himself a keen controversialist. My subject of to-night is but half the story. Even the strictest devotion of the time at my disposal to a survey of the scientific work of Tyndall will not allow of more than a very imperfect and fragmentary treatment. During his thirty years of labour within these walls he ranged over a vast field, and accumulated results of a very varied character, important not only to the cultivators of the physical sciences, but also to the biologist. All that I can hope to do is to bring back to your recollection the more salient points of his work, and to illustrate them where possible by experiments of his own devising. In looking through the catalogue of scientific papers issued by the Royal Society, one of the first entries under the name of Tyndall relates to a matter comparatively simple, but still of some interest. It has been noticed that when a jet of liquid is allowed to play into a receiving vessel, a good deal of air is sometimes carried down with it, while at other times this does not happen. The matter was examined experimentally by Tyndall, and he found that it was closely connected with the peculiar transformation undergone by a jet of liquid which had been previously investigated by Savart. A jet as it issues from the nozzle is at first cylindrical, but after a time it becomes what the physiologists call varicose; it swells in some places and contracts in others. This effect becomes more exaggerated as the jet descends, until the swellings separate into distinct drops, which follow one another in single file. Savart showed that under the influence of |