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8 THE MARINE RECORD. i May 4, 1899. SOME EFFECTS OF THE INCREASED SIZE OF STEAMSHIPS. Before a recent meeting of the Graduate Section of the Institution of Engineers and Shipbuilders in Scotland, Mr. Herbert C. Sadler, B. Sc. (assistant to Professor Biles, of the Chair of Naval Architecture in Glasgow University), read a paper entitled ‘‘Some Effects of Increase in size of Steamships,”’ in which he sought to show that the develop- ment of the modern steamship had followed the well-known law of evolution, the latter types having been the natural outcome of the general advance of commercial enterprise and scientific application. The author, in opening, sated that the large number of cargo and passenger steamers over 500 feet in length, built during the past few years, must haye suggested to the inquiring mind the question: When would this increase of size reach its limit? Not only in size, but also in speed there had been a corresponding advance, the 10-knot freighter having been slowly but surely replaced by its more powerful rival with a sea speed of 14 knots. In the powerful passenger liners there had also been a tendency to increase speed. Merchant ships might for convenience be divided into two classes, viz., passenger ships and cargo ships. Ships of the second-class were many and varied, but it was the larger type which would be considered. The point which must have struck everyone interested was the increase in the size of such vessels which had taken place within the last few years. In most of the trans-Atlantic lines, notably in the White Star and Leyland line, the newer cargo vessels varied in length from 500 to 600 feet. Speaking roughly, the cargo-carrying power depended upon the length, the stability on the breadth, and the strength on the depth. The draught was usually fixed by considera- tion of service, z. ¢., depth available in harbors, docks, or bars at the mouth of rivers; so at the onset one element of the displacement was fixed, and the only two variables were length and breadth. Stability was no doubt a good thing, but it was quite possible to have too much of it. If a vessel had always still water in which to float, a great amount of stability would not be objectionable; but as this state of things did not asarule obtain at sea, great stability was objectionable. Put shortly, a vessel that was too stiff was a bad sea boat. Hence it was that the tendency had been to increase length rather than beam in order to obtain sufficient displacement to carry the large amount of deadweight that was common in the latter types. The question of speed had also had some effect in shaping the development in cargo ‘ships. The latter vessel carried much more coal than form- erly, especialiy on the Atlantic service. With limited length ‘and draught the beam must be increased if great - cargo-carrying power was required, notably so in vessels trading with South American ports, especially Buenos Ayres, Increase of beam was not in itself objectionable, provided that means were taken to raise the center of gravity of the vessel as a whole, so that the metacentric height was reduced. To effect this ballast tanks at the ’tween deck height, instead of at the bottom of the ship, had been sug- gested, and without doubt these would eventually be adopted. But with limited draught, increase of length rather than breadth produced a better seaboat if increased amount of deadweight was required. With increased size of vessel cargo could be carried more economically. The amount of deadweight available with a given form of ship at a given speed increased—as the size of the vessel increased —at a greater ratio than the displacement. The author then showed a series of curves representing various sizes of vessels and powers required for a constant speed, the form of vessel remaining the same throughout, and said that from these curves the power required for a series of vessels of the same form, but varying displacements, and the amount of displacement available for cargo-carrying pur- poses, could be ascertained. Assuming roughly that the working expenses varied as the power, and the earning power varied as the deadweight carried, the saving in the ' larger vessels was immediately apparent. Starting with a 10,000-ton ship, for example, and increasing to 20,000 tons, or 100 per cent. the power was increased about 50 per cent., and the carrying power about 120 per cent. These figures were only approximate, of course, but they illustrated the general results obtained from increase of size. ‘The author showed by another set of curves the effect of increase of speed with constant displacement, on indicated horse-power, and on the weight of machinery and coals to be carried. From these curves it was at once apparent that increase of speed meant a great sacrifice in weight of cargo carried, as well as increased first cost and running expenses, With increase of speed more journeys could be made in the year, but the whole question was one for shipowners more than shipbuilders. Referring to fast passenger steamers, the author said that the general effects of increase of size in their case were the same as for cargo steamers, but speed was of primary importance. For a series of passenger steamers of about 20 knots speed, of varying sizes, curves had been prepared, and the general results were similar to those referred to. In this case, however, the amount of weight available for cargo, stores, etc., at 12,000 tons displacement was very small and if the curves were continued to lower displacements it would be found that under the given assumptions a vessel of about 10,000 tons would just carry her own weight and coals, and have no margin for cargo. Unless, therefore, the passenger receipts were sufficiently high, the vessel would not pay. From these curves it was seen that if the displacement was increased 100 per cent. the power for the same speed was only increased about 60 per cent. and the carrying capacity about 250 percent. If an extra knot was required the increase from 20 knots to 21 knots meant a much greater relative increase of power; hence increased cost and weight of machinery and less mar- gin for cargo. The last decade had seen a steady increase in the length of fast passenger and cargo vessels, viz., from 500 to 700 feet. This continual increase could scarcely be due to the childish idea of one individual having a larger and more costly toy than another; for although for adver- tising purposes it might be advantageous to say that one possessed the largest or fastest ship in the world, if the receipts did not show a proportional increase it was hardly conceivable that shipowners would be philanthropic enough to place orders for large vessels merely to test shipbuilders’ engineering powers and skill. The advantages obtainable by increasing the size of vessels had no doubt been recog- nized by some shipowners; and, if trade warranted, larger and faster steamers would, doubtless, continue to be built. The port of New York had perhaps the largest service of large and fast vessels in the world, and the result of the passenger. traffic for the past eight years showed that in the mean there had been a steady falling off from 1890, at the rate of 5 per cent. per annum. This might be explained away in various ways, but the fact remained that there had been a steady falling off, accompanied with an increase in the size of steamships. Next year would see two more vessels on this route larger than any at present running, and if passenger traffic did not take a sudden turn upwards these latest off-springs of man’s ingenuity would scarcely add to the prosperity of their elder sisters. If larger accom- modation for cargo and passengers was required, with the present materials for construction and methods of propul- sion, then ships would continue to increase in size; but without being too prophetic, the author felt inclined to think that we were at present near the limit. In the future it was more probable that shipbuilders and engineers would turn their attention to reducing weight instead of increasing size. With the adoption of some of the stronger alloys of steel, or perhaps some new material for hulls, with the universal use of water-tube boilers, and some improved form of engine, such as the steam turbine, great saving of weight could be effected. Perhaps each of these would in turn have its day, and some as yet unknown method of propul- sion be adopted; and in the dim future, when the historic New Zealander mused over the rapidly decreasing rust heap that was once the Oceanic, he might be excused a smile at what would seem to him to have been a most unnecessary waste of material and labor. ae _ a> PROPOSED PACIFIC CABLE. The proposed Pacific cable to connect British Columbia with China and Australia has received a set back. A copy of an agreement entered into between the British government and the Eastern Extension Australia & China Telegraph & Cable Co. in 1893, by Lord Ripon, has just been made public. In this agreement the British government promised not to lay nor permit to be granted any concession for laying any sub- marine cables connecting with Hong Kong, Singapore or Labuan unless found necessary in the general interest of Great Britain. If the proposed cable from Canada is to be deprived of the large business which it was expected it would receive from a connection at Hong Kong it will be seriously handicapped. Great Britain, according to the terms of the agreement, may purchase the cable of the Eastern Extension company on 12 months’ notice for the sum of £300,000, SOME ASTRONOMICAL NOTES FOR MAY. [Communicated. ] The principal winter constellations that have so long adorned our evening sky, may still be seen in the early even- ing toward the west, but they have already lost much of their usual brilliancy and before the close of the month most of them will have disappeared, lost in the rays of the advanc- ing sun. Capella in Auriga and Castor and Pollux in the Gemini, by reason of their greater northern declination may survive the month and be seen toward the northwest. Arcturus in Bootes is approaching the meridian and during the latter part of the month will be the leading first magnitude star in our evening sky. Toward the northeast Vega, in Lyra is again coming into view and will soon rival Arcturus in brilliancy and beauty. Leo with the first magnitude Regulus is now passing the meridian, and toward the southeast near the horizon the ruddy Antares in Scorpio will soon appear. Spica, the blue star in Virgo, is now seen at a disadvant- age, by reason of its proximity to Jupiter. Ursa Major with its great dipper will be nearly over head in the evening dur- ing the month. Mercury, the nearest known planet to the sun, may be seen by those who search for him, for a few mornings, be- fore or after May 10. Venus is still the bright morning star seen in the east, but by reason of her increasing distance from us her brightness is constantly diminishing and is now but about one-third of what it was in January. Mars is no longer a conspicuous object in our evening sky, but may be found in Cancer next east of the Gemini. brightest star in that part of the heavens and may be easily recognized as the red planet. Jupiter, the giant of the solar system, is the bright planet in the east at early evening and is the most conspicuous object in oun evening sky when the moon is absent. Saturn is now classed as an evening planet, for he rises before midnight, but he will not be available for observing at seasonable hours in the evening before next month. Two telescopic comets have been discovered recently, but they are of no special interest to ordinary observers. The most remarkable astronomical discovery of recent date, is that of another satellite of Saturn, by Professor W. H. Pick- ering, of Harvard college observatory. Thus the number of known satellites belonging to our system is increased to twenty-two, nine of which are attendants upon the ringed planet. The new satellite was discovered by means of pho- tography, and is said to be thirty times as distant from its primary as our moon is from the earth; its period of revolu- tion is seventeen months. Only those who have access to the largest telescopes can hope to ever have a glimpse of this newly-discovered member of the solar system. Nothing remarkable in the line of sun spots has been ob- served since last report. ; One small spot, brought into view by rotation, is now passing across the sun’s disk. The distance between the earth and sun is constantly in- creasing, and the northern hemisphere of the earth is slowly turning toward the sun and thus daily increasing his meri- dian altitude. D. SATTERTHWAITE, ee ee AKE NAVAL RESERVE DRILLS. A letter forwarded from Assistant Secretary of the Navy Allen to GovernorPingree of Michigan enclosing the schedule of drills for the naval militia for the lake states as follows: “The Michigan to beat Cleveland, or such other Ohio port as the governor of the state may select, July 5, to in- struct Ohio naval militia, for a period of eight days; to be at Detroit, July 20, to instruct Michigan naval militia, for the period of eight days; to be at Chicago Aug. 7, to instruct Illinois naval militia, for a period of eight days; the Michigan to be on this service from July 5 to August 15,”’ Iieutenant Strathearn Hendrie, of Detroit, had a confer- ence with Mr. Allen and Lieutenant Sutherland, who has charge of the naval milltia matters, andhe says that the reserves throughout Michigan will take an active interest in the cruise this year, and will thus secure as large an allot- ment as possible of next year’s appropriation. ro ol oe THE Nautical Almanac, now in its 6oth year, published by T. S. and J. D. Negus, chronometer and nautical instru. ment manufacturers, 140 Water street, New York. The Almanac is also an excellent coast pilot and is considered an indispensable aid to those engaged in sailing in the coast trade. The thanks of the RECoRD are due Messrs. T. S. and J. D. Negus for a copy of the latest edition of their valuable little work, He is still the -