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24 MARINE REVIEW. [August 15, EXPERT'S COMMENT IN HYACINTH AND MINERVATRIALS. Reviewing the interesting series of trials of the Hyacinth with Belle- ville boilers and the Minerva with cylindrical boilers, an expert in the London Times says: The trials have been made by request and under the supervision of the boiler committee appointed for the purpose of investigating the very important question concerning the wisdom of fitting water tube boilers on board our war vessels, and in this capacity their investigations are necessarily directed more particularly toward the Belleville boiler, owing to its having been adopted in our navy, for large war vessels, practically to the exclusion of other types. It should be borne in mind that several miembers of the house of commons have declared, in the most emphatic manner, their opinion that water tube boilers generally, for marine pur- poses, were both dangerous and excessively wasteful of fuel. It was in consequence of these declarations that the committee was appointed to investigate the truth of such statements and thereby alleviate the anxiety in the public mind. It was desirable to make comparative trials between the cylindrical and Belleville boilers, working, as far as possible, under precisely similar sea-going conditions. It was difficult to make such com- parisons, owing to the fact that our navy does not possess two vessels of any considerable horse power, having precisely similar dimensions, lines, displacement, and propelling machinery, fitted with boilers of the two types in question. The best that could be done in the circumstances was to select two second-class cruisers of practically equal displacement and maximum indicated horse power, the one being fitted with Belleville boilers, the other with those of the cylindrical type commonly known as Scotch boilers. The general dimensions of the two ships and of their machinery are as follows: The Hyacinth--Length, 350 ft.; breadth, 54 ft.; mean draught, 20 ft..6 in.; displacement, 5,600 tons; maximum horse power, 10,000; twin screw engines of four cylinders; high pressure cylinders, 26 in. diameter; intermediate pressure cylinders, 42 in. diameter; low pressure cylindes (2), 48 in. diameter; stroke, 2 ft. 6 in.; revolutions at maximum power, 180 per minute. The Minerva--Length, 350 ft.; breadth, 53 ft. 6 in.; mean draught, 20 ft. 2 in.; displacement, 5,600 tons; maximum horse power, 9,600; twin screw engines of three cylinders; high pressure cylinders, 33 in, diameter; intermediate pressure cylinders, 49 in. diameter; low pressure cylinders, 74 in. diameter; stroke, 3 ft. 3 in.; revolutions at max- imum power, 140 per minute. It will be noted that the vessels and their propelling machinery are not precisely comparable; and consequently so far as speed of ship per I.H.P. or efficiency of the engines are concerned, no heed need be taken of the results of the trials. The trials have been carried out for the pur- pose of comparing, as far as practicable, the efficiency of the two types of boiler from two points of view--first, as producers of steam from a given weight of coal, in other words, coal consumption; secondly, their capacity for producing an ample and constant supply of steam for a long run at maximum speed, having no special regard to economy of fuel. Those who have so bitterly criticized the adoption of the Belleville boiler in our navy have laid special emphasis upon alleged excessive coal con- sumption, and in the second place they have expressed their conviction that it would be impossible to maintain a high speed for any considerable period with these boilers. The trials having now been completed; a brief*summary of the prin- cipal results will be interesting to show whether the confident assertions that the strength of our navy has been jeopardized by the introduéti@n of these boilers have, or have not, any foundation. a ee First coal consumption trial, 24 hours' duration, 2,000@.H.P.: of water per Mean. I.H.P. Ib. of coal. The Hyacinth 3003, 0.6. ....5. 48... 2,053 9.69 The. Minetvary 0 a 2,142 8.54 Result--13.4 per cent. in favor of Hyacinth's boilers. Second coal consumption trial, 24 hours' duration, 5,000 H.P. Actual evaporation of water per Mean. I.H.P. lb. of coal. Mile Hyacinth 3.0.55. .6. eee ie. oe 4,992 9.41 Whe Minerva i). 6.2 Sea eee, 5,155 8.87 Result--6 per cent. in favor of Hyacinth's boilers. Third coal consumption trial, 12 hours' duration for Hyacinth, and eight hours for Minerva, 8,000 H.P.: Actual evaporation of water per Mean. I.H.P. lb. of coal. Ue Eyacinth: (12 hours). 3...... oes 85105 9.89 Mie Minetva (8 hours)... .3,1......2.... 8,114 8.19 Result--20.7 per cent. in favor of Hyacinth's boilers, Fourth coal consumption trial, eight hours' duratiou: The Hyacinth was tried for eight hours at a maximum power of 10,000 H.P., but no trial was made of the Minerva at full power, as it was considered undesirable to force the cylindrical boilers to their original specified maximum power of 9,600. The mean I.H.P. for eight hours in the Hyacinth was 10,181 and the actual evaporation of water per pound of coal during that period was 8.8, showing that at the maximum power of over 10,000 the Hyacinth boilers were doing better duty per pound of coal than the Minerva cylindrical boilers did at 8,000 H.P., the latter having evaporated only 8.19 of water per pound of coal at the lower power. After these trials certain modifications were made in the boilers of the Minerva, and upon trial, with half the boilers, burning coal at the rate equivalent to that consumed upon the 8,000 I.H.P. trial, the evaporation per pound of coal was found to be about 9 per cent. better, consequently, in comparing the results of the third coal consumption trial, it would perhaps be fair to place 9 per cent. to the credit of the Minerva. The vessels were now prepared for the last of this series of trials, which consisted of a run from Plymouth to Gibraltar, each vessel to maintain, as nearly as possible, 7,000 H.P., and after touching at Gib- raltar to proceed until the coal on board was exhausted. The return run from Gibraltar to. Portsmouth was to be at maximum possible speed, without any regard to coal consumption. Both vessels started at the "= "Actual evaporation appointed time and touched at Gibraltar, signalling all well, and pro- ceeded to exhaust their coal supplies. After steaming 103% hours at 7,000 H.P. the Hyacinth was obliged to put in to Gibraltar, owing to having lost a considerable quantity of water through leaky feeding con- nections. The Minerva returned, after steaming about 150 hours, having stopped for some two or three hours owing to derangement of the ma- chinery. Taking into consideration the time under way and the H.P. developed, the coal consumption per pound of water evaporated appears to -be slightly in favor of the Hyacinth, but for practical purposes the results may be taken as equal. It is only fair to note, however, that the loss of water, through defective feed connections, must have told con- siderably against the efficiency of the Hyacinth boilers. _ Regarding the home trip the expert says that from a scientific stand- point the most instructive part of the race was when the Minerva steam- ing at 8,400 I.H.P. drew away from the Hyacinth steaming at 9,400 I.H.P. It showed that the Minerva possessed an advantage, either in the form of her propellers or in the superiority of her lines, for when the Hyacinth made a sprint of three hours at 10,000 I.H.P. she merely churned the water without appreciably increasing her speed. COMPACTNESS IN GENERATING SETS. A distinctive feature of small and medium sized generating sets is the compactness which is secured in late designs. Herewith is illustrated one which possesses some distinctive features of novelty. The running gear of the engine is entirely enclosed, all parts are oiled from sight feed oiling devices on the exterior, and access to the interior is provided through a tight fitting door. The engine is of the compound vertical type and its general appearance is very similar to the double vertical engine of the same company, the B. F. Sturtevant Co. of Boston, Mass., by whom a line of these generating sets is now being built from their own designs. The engines range from a 4-7x4 up to a 8%4-15x7. The cylinders are in a separate casting from the frame, to which they are bolted, thus rendering them easily removed for repair. Two valves are employed, one controlling admission of steam to each cylinder, and motion is transmitted through a rocker, provided at its outer end with an accurately fitted ball-and-socket joint, and at its inner end connected by link to the valve stem yoke. The cylinders are thoroughly lagged to prevent condensation, and danger of damage from water in the cylinders is avoided by the use of special auto- matic relief valves. The generator is of the standard four-vole Sturtevant type, with mag- net frame of special magnet steel, with field cores cast on. To these the pole shoes are secured by cap screws. The armature is of the barrel wound toothed drum type. Ventilation is effected by the use of specially con- structed air ducts between the laminae of the core. These convert the armature into a blower and create a strong draft through the windings. The winding for low voltage machines is of copper bars with easy bends. High voltage machines are wire wound with machine formed coils. The commutator consists of drop forged segments of pure copper, secured be- sees cast iron flanges of spider construction, which allow free circulation of air. All machines are fitted with carbon brushes mounted in holders of the sliding socket type. The field coils are double cotton covered and are rendered absolutely oil and water proof by saturation in a special com- pound and subsequent baking at high temperature. The armature is sub- jected to a similar treatment. All machines are given a full load test for a sufficient time to bring every part to its maximum temperature, which never exceeds 40° Cent. Mr, P. H. Cheney of the firm of P. H. Cheney & Sons, ship chandlers at Ashtabula, died at his home on Sunday afternoon. He was one of the best known marine men on the lakes and had had a long and useful career. For eighteen years he was light-house keeper at Ashtabula and for nearly twenty years past had been engaged in the ship chandlery trade at that port. He had a personal acquaintance with practically every cap- tain on the lakes and was universally esteemed. His death was due to a number of complications from which he had suffered for a year past. He was 65 years old.