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rer Capt. Alex. McDougall's Patents. WRECKING BOAT--SPECIFICATION FORMING PART OF LETTERS PATENT NO. 488,574--DATED DEC. 27, 1892--APPLI- CATION FILED SEPT. 17, 189 1I--SERIAL NO. 406,01I--NO MODEI,. In these specifications Capt. McDougall explains that his invention relates to a vessel adapted to be used in raising sunken wrecks, removing rocks, snags, &c. "I propose," he says, "'to take one of the improved tow boats or steam tow boats, invented by me and described and claimed in various letters patent and applica- tions for letters patent, and place a number of heavy metal pipes,ar- ranged vertically therein, in line with each other and extended from the extreme bottom to the extreme top of the boat.' These pipes will not interfere in any way with the carrying capacity of the boat, so that it may be used for carrying freight and for tow- ing other boats when not engaged in wrecking. When the ves- sel is to be used in raising sunken wrecks I will first place a suitable wooden or metallic scaffold within the hull, adjacent to each vertical pipe, and resting on the false bottom, so as to firmly support the top or deck and bring all the strain upon the bottom, which is the strongest part of the boat. T'wo of these vessels will now be moved to the scene of the wreck and will be placed on each side of the sunken boat, and parallel therewith. A very heavy chain will then be passed down through each ver- tical pipe and firmly secured at its upper end, preferably by means of a heavy steel bar pressing through one of the links of the chain and resting upon the deck. 'These chains are now passed under the sunken vessel by divers or by other means, and the chains from one wrecking boat are secured to the chains of the other wrecking boat. Water is now pumped into the water bottom and tanks of each wrecking vessel, or into the hull of each vessel, soas to submerge each boat to the proper level which will slack up the chains. The slack is now taken up so as to make the chains taut, and the water is pumped out of each wreck- ing vessel by means of the steam pumps which are carried on each boat. Each boat being now lightened will rise and the sunken boat will be carried clear of the bottom so as to swing on the supporting chains. The two vessels are now moved in toward shoaler water until the wreck grounds. 'The wrecking vessels are again submerged, by pumping water into them, and the slack of the chains is again taken up. Once more the wreck- ing vessels are relieved of the water therein by the steam pumps and the sunken boat will be again raised and moved in toward shoaler water and again grounded. 'These operations are con- tinued until the wreck has been raised sufficiently to be relieved of its cargo and pumped out. As is well known the operation of raising submerged wrecks can be greatly facilitated by working with the tide, so'as to pump the water into the wrecking vessel on a low tide or when the tide is going out, and pumping the water out of each wrecking vessel on a high tide or when the tide is coming in. In this way the rise of the tide will be util- ized in lifting the wreck. The principal object of my present invention is the production ofan improved wrecking vessel which can be used for carrying freight or for towing other vessels when provided with propelling mechanism, and which will be of the highest efficiency in both capacities. "Another object of the invention is to produce a wrecking vessel wherein all the strain will be brought on the bottom there- of and not on the deck as is now the case, and wherein the *Under this heading we will publish specifications accompanying letters, patent granted to Alexander McDougall since his first application for a patent on the whale- back type of vessel, May 1,1880. MARINE REVIEW. ae 9 weight of the wreck will be impended from the central part of the boat, so that there can be no danger of the wrecking vessel being thrown out of her equilibrium. Fora better comprehen- sion of the invention attention is directed to the accompanying drawings. Fig. 1 is a longitudinal view partly in section of one of my improved tow boats when used as a wrecking vessel, Fig. 2is across sectional view of the same, and Fig. 3 is an end elevation illustrating the manner of putting the improved vessel in use. A is one of my improved tow boats converted into a wrecking vessel. The particular form of boat illustrated in the drawings is similar in most respects to that patented by me in this country on June 3, 1890, and numbered 429,468, being pro- _ vided with an arched top, a curved bottom, straight parallel sides, a spoon shaped bow and a skeaged stern. B isthe water bottom, beneath the false bottom, upon which the cargo rests, and C and D are water tanks which are placed in the bow and stern of the vessel, beneath the floors of the forecastle and after cabin respec- tively. The water bottom B and tanks C and D are to be filled with and relieved of water by means of steam pumps which are carried on each vessel and which mav be placed either in the bow or stern or both. If desired there may be suitable connections from the said steam pump or pumps by which water may be pumped into and out of the hull proper of the vessel. E E are a number of heavy metallic pipes which are arranged on in front of the other in the hull of the vessel and extending from the ex- treme bottom to the extreme top thereof. Fis a heavy angle iron collar. at the bottom part of each pipe E. 'The vertical flange of each collar F is riveted to the inside of the lower part of each pipe. By means of this collar F the lower part of each pipe is secured very firmly and there is no danger of leaking. By extending the vertical flange of the collar F up into the in- terior of its respective pipe E it prevents any chafing or wearing by the chain which passes down through the pipe. Gis anangle iron collar secured to the outside of each pipe E and to the top of the false bottom and serves to strengthen' the pipe at this point. This collar also gives a bearing for the false bottom on the pipes E E and prevents water from leaking into the hold of the vessel from the water bottom. H is another angle iron collar which is riveted to the inside of each pipe E and to the bottom side of the top or deck of the vessel. When the improved vessel is to be used for the purpose of raising submerged wrecks I make use of asuitable scaffold I, which is built up in any suitable way between the false bottom and the top or deck of the vessel, as shown in Figs. 1 and 2. By means of this scaffolding the strain which is imposed on the deck is taken up by the false bottom and from thence by the intermediate frame work to the bottom of the vessel, whichis best calculated to stand this strain, as it -- rests upon the water. It will-be understood that this scaffold- ing is only temporary and is to be used only when the vessel is to be used as a wrecking boat. J J are chains which pass down through the pipes E E and are provided with some suitable de- vice, such as a heavy steel bar passing through one of the links, by which the chains may be supported by the deck of the vessel in such a manner that any slack may be quickly and easily taken up. At the lower end of each chain is a suitable form of tackle or hook by which the chains from one wrecking vessel may be securely fastened to the chains of the other wrecking vessel. "In Fig. 3 is very clearly shown the manner of putting the vessels into use in wrecking a submerged steamboat. In case the water which will be contained in the water bottom and tanks is insufficient to properly submerge the vessels, water may be pumped directly into the hold of the vessel. WhatI claim as new and desire to secure. by letters patent is: An improved wrecking vessel, consisting of a hull, having a curved top, straight parallel sides, spoon-shaped bow and skeaged stern, and water-tanks within said hull; vertical pipes HF E extending through said hull from top to bottom; and chains J J passing down through said pipes, substantially as set forth." . The first steamer built by the Cunard company was the Britannia, which was launched Feb. 5, 1840, or fifty-three years ago. She was built of wood by Robert Duncan at Port Glasgow, her length being 207 feet; breadth, 34% feet; depth, 22% feet; tonnage, 1,156; passengers carried, 115; cargo, 224 tons. The engines, by Robert Napier, were side levers with two cylinders, 72 inches diameter by 82 inch stroke of piston, driving paddle wheels 28% feet diameter. Steam of 20 pounds pressure was provided by four flue boilers,with twelve furnaces, which consumed 38 tons of coal per day. 'The speed of the vessel was 8/4 knots, with the engine developing 710 indicated horse power coal, con- sumption, over 5 pounds per indicated horse power; time in making voyage, fourteen days.