slightly deeper and with considerable increase in length. The pontoons removed could easily have been converted into tending floats, or even small dry docks, for torpedo craft.

As regards the future lengthening of a dock of this type, the fact must not be lost sight of that such lengthening should be accomplished by the addition of two (rather than one) new sections, since it is inadvisable to bring a through joint at the center of the dock. For commercial purposes this caution is not necessary. since it is the current commercial practice to place slight reliance in the longitudinal stiffness of the dock. For naval purposes, however, the loosely connected sectional dock would not be tolerated, and the theory of design assumes that the side wall girders carry the bending moment due to the ship load and flotation. A central joint could be made of such strength as to provide for the maximum bending moment usually coming at the centre of the dock, but these joint sections would of necessity be so cumbersome as to make it cheaper to rivet them solidly, thereby sacrificing the ease of self-docking claimed by the inventor. In any event docks designed on this plan should anticipate future expansion by the use of low unit stresses, or increased load assumption.

One of the most valuable features of this design lies perhaps in the possibilities offered for rapid emergency construction. Should the need for such a dock arise suddenly, instead of waiting from one and one-half to two and one-half years for the delivery of the structure, contracts could be awarded to different firms for the side walls and various pontoons, and the whole assembled upon delivery. In time of war it would be possible to construct a 30,000-ton dock on this plan in four months time. Another advantage which seems well worthy of consideration is the ease and comparative safety with which such a dock could be towed long distances at sea. Instead of the risk attending the transportation of the dock as a wholeand only those who are familiar with the towing of the "Dewey" to Manila can realize the immensity of such an undertaking-it would be a comparatively safe and simple undertaking to tow each pontoon separately, and to so construct side walls as to enable them to be floated horizontally and towed as ordinary lighters.

CIVIL ENGINEER F. H. COOKE, U. S. NAVY.-The ideal type of floating dry dock, for naval purposes at least, appears to be the closest approximation to the "solid" or "box" type, compatible with safety and convenience of self-docking. Other important considerations are the ability to enlarge the dock with minimum expenditure of time and money, and rapidity of first construction; this latter point appears to be of prime importance, and under certain conditions might well be the determining feature of the design.

The type of dock proposed by the author appears to satisfy the requirements of facility of self-docking, ease of expansion, and rapidity of construction, to a marked degree, especially the two latter, in which the proposed type seems to possess very considerable advantage over the "Dewey" type. It seems to the writer, however, that there is too great a sacrifice

of longitudinal rigidity in breaking the continuity of the side walls. The ability to separate a dock into two or more smaller docks, self contained though each may be, does not appeal to the writer as of material advantage, per se, especially when moorings must be shifted, new moorings provided, connections made and unmade, etc., and when this ability is had at the expense of side wall continuity, it appears to be rather dearly bought.

As to expansion lengthwise, it appears to the writer that the continuous side walls of the original dock could readily be designed to admit the addition of a pontoon or pontoons at either or both ends; such metal as might be required to give the lengthened dock the requisite rigidity would, as surplus in the original length, be doing good service in decreasing deflections.

As to expansion vertically, it would appear that increase in lifting power {without increase in length could well be had by constructing a low steel bulkhead across each end of the dock, to say, within one foot of the top of the blocks. For a dock 600 feet long by 150 feet overall width, an increased depth of 3 feet would increase the displacement by about 7500 gross tons, and this without change in pontoons or increase in depth of dock berth. The joints between pontoons, and between pontoons and side walls, should be made sufficiently water tight against the small head they would be required to resist, without difficulty or complication. Suitable drainage connections could easily take care of any leakage, the deck being given a camber for the purpose.

As to rapidity of construction, it appears to the writer that this need be not at all reduced were the side walls made continuous.

Although the dock would naturally be built on square lines, and of practically uniform detail, it is possible that perfect matching of holes would be found wanting, when it was sought to replace a pontoon by a spare. As a pontoon self-docked would materially reduce the length of the dock available for the simultaneous docking of ships, the provision of a spare pontoon does not seem to the writer to be justified solely for this purpose, but a spare might be exceedingly useful in case of injury to a pontoon.

The economy of first cost effected by reducing the depth of the end pontoons appears to the writer as of doubtful advantage, considering the permanent decrease in end displacement occasioned thereby, which might be of great disadvantage under certain conditions, as of a ship badly down by the bow or stern.

In the author's proposed type, as well as in the dock with continuous side walls, it would appear not difficult to make suitable connections between pontoons and walls, connections which would virtually make the transverse girders or trusses of the pontoons, and the vertical frames of the side walls, continuous U-shaped structures, yet which could easily be made and unmade by even working within the side walls. The pumps, which it would appear should be set close to the bottoms of their respective pontoons, could be readily coupled to and uncoupled from their vertical shafts, without disturbing the shaft stuffing boxes. Considerable additional longitudinal rigidity could be had by connecting together the ends of the

longitudinal girders which would naturally be built in the pontoons, these connections could be made of great strength, yet with their lower portions above water at light draft and accessible for inspection and repair from above. It would appear that the additional first cost of such connections, and the additional labor to make and unmake them, would be amply repaid by the gain in rigidity, and that such connections, together with continuous side walls, should go far toward approximating the "solid" type, while providing a design admitting of rapid construction, easy enlargement, and convenient self-docking.

The True Story of the America.
(SEE No. 142.)

In the communication of Mr. William Barry Meany, M. D., which appeared in the UNITED STATES NAVAL INSTITUTE PROCEEDINGS, No. 142, June, 1912, under caption "The True Story of the America," second paragraph, line two, page 748, which reads, "and wherein no mention of, or any reference to, the name of Commodore John Barry appears-reads:" It should have read and wherein no mention of nor does any reference to the name of Commodore John Barry appear-reads: "

PROFESSIONAL NOTES.

Prepared by LIEUT.-COMMANDER RALPH EARLE, U. S. Navy.

The construction of the new port at Valparaiso will provide a harbor capable of berthing the largest modern ships and will include: A breakwater, 945 feet long; a quay wall 2066 feet long; strengthening and extending the Fiscal wharf to a length of 1214 feet; a quay wall 690 feet long; a jetty 820 feet long and 328 feet wide; a coal wharf 656 feet long and 100 feet wide, including coal transporters, hoists, cranes and railway, etc. All the necessary customs and other warehouses, administration buildings, lighthouses and coastguard stations are also to be provided. The new harbor, when completed, will have a depth of 40 feet of water.—Shipping, Illustrated.

"VIRIBUS UNITIS."-Sketches show this to be a vessel with two stacks, two masts, and four center-line turrets each containing three 12.2-inch guns. The length is 488.7 feet, the beam is 88.5 feet, the displacement is 20,500 tons, and speed will be greater than 22 knots. Battery is twelve 12.2-inch 50-caliber guns, twelve 6-inch and eighteen 2.8-inch guns. Armor belt about 11.5 inches in thickness, protective deck 2.4 inches, turrets 12 inches.

There are four under-water tubes, one in bow, one in stern, one on each side. The torpedoes are 20.7 feet long, weighing 2794 pounds, and give at 3280 yards a speed of 40 knots.

Battleships II and VII which follow are to be similar, but are to have six tubes.

NEW TYPE OF GUN AND ARMOR PLATE-A new gun of 13.7-inch caliber has been constructed at the Skoda works of Pilsen, and proved. This gun is the type designed for the arming of the battleships succeeding the Viribus Unitis which carry twelve 12-inch. This new gun is exactly like the guns built by Vickers and Armstrong for the English service. The shell will weigh 1518 pounds, and will give a muzzle energy of 22,000 tons. The new battleships will be armored with some new plates called "electric armor," made by the Wittkrowitz works which manufacture the most of the armor plates for the Austrian Navy. The principal superiority of these plates will be in an annealing obtained by their passage through an electric furnace at a certain fixed temperature. This operation will give a metal with a very close grain, perfectly regular and homogeneous, with a resist ing power much superior to the cemented steel of the Krupp process, and also at less cost.-Le Yacht.

DEFECTS IN NEW BATTLESHIPS.-A serious error has been made in the calculations of the weights of the battleships of the Viribus Unitis class, which prove to be overloaded by 1000 tons, their armor belt is submerged, and their maneuvering qualities greatly reduced. This error proved to be due, at least in part, to the fact that in the calculation the weights of the gun carriages were neglected. A lighter type of mounting was tried, then lighter armor plates, but neither sufficed, and the four Viribus Unitis are of too deep a draft.-Le Yacht.

ACTIVE SQUADRON.-A division of cruisers always in shape to go to sea was added to the active battleship squadron. This division comprises the battle cruisers Sankt Georg and Maria Theresa, the scouts Admiral Spaun and Aspern.-Le Yacht.

The battleship Rio de Janeiro has been greatly delayed by modifications in the design. She is 632 feet long and 89 feet beam. The side armor is 9 inches, as is also the turret armor. There are three armored decks (2 inches, 11⁄2 inches, and 1 inch). Will be driven by Parsons' turbines, and have Babcock & Wilcox boilers.

A cruiser Ceara is on the ways, also three submersibles of the Laurenti type have been built at the F. I. A. T. San Giorgio yard, Spezzia.

A bill to authorize the construction of a new harbor in Brazil for naval purposes, at a cost of $20,000,000, is reported to be at present before the government, and the Bay of Ilha Grande has been suggested as the most suitable spot. The proposal includes erection of docks and buildings, but the provision of defence and similar work would involve an additional expenditure of $10,000,000.-Shipping, Illustrated.