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1900.] MARINE REVIEW. 17 or lag with reference to their respective e. m. f.'s, and thus magnetize or demagnetize the field magnets so as to automatically produce the necessary balance between them. This method of balancing is also of great advantage in eliminating the sparking at the brushes and other wasteful heating, which occurs when an armature becomes decentralized, due to wear of the bearings or from other causes. When, on account of the armature being out of center, the air gap on one side is greater than that on the opposite side, the potential generated in the coils on the side having the smaller air gap is considerably higher than that generated in the coils under poles of the same polarity on the opposite side; conse- quently, a current corresponding to this difference of potential flows from one section of the winding to another through the brushes and connect- ing leads. By the use of this balancing method, the armature could be consid- erably out of center and no injurious results occur, as the balancing cur- rents do not flow through the brushes, but through the specially provided connections, as explained above. In addition to this, the fact that the currents in these conductors are alternating currents, which are "lead- ing" in some coils and "lagging" in other coils, enables a very small current to effectually balance the circuits. Should the armature get out of center by wear of the bearings, this method of balancing the magnetic circuits is specially advantageous in preventing any heavy magnetic pull on one side of the armature. The pull which may be excited by one side of the field on a large armature, even if out of center by a small fraction of an inch, may become several tons unless this method of balancing is used, but by thig method of balancing, the induction under all poles is maintained practically the same, causing the magnetic pull to be equal at all poles and preventing an unbalanced pull. LIFE-SAVING APPLUANCES. In a letter to the American Shipbuilder of New York, James Rich- ardson scores the steamboat inspection service for loss of life that has occurred of late on several wooden barges along the Atlantic coast, due mainly to the lack of proper life boats or other life-saving appliances on these old vessels--worn-out hulls that are towed in the coal trade. The correspondent intimates that if the heads of the vessel inspection branch of the treasury department are not backed up by laws pertaining to such vessels it should bbe their duty to bring about the necessary regulations and also seek changes in laws already on the statute books which are said to be worse than useless. The communication is in part as follows: "There are many instances where lives were lost on vessels of this kind that might have been saved if suitable life-saving appliances were to be had. The style of davit for launching ships' boats is not men- tioned in the statutes, nor in the regulations governing the equipment of steam vessels. Whether this is a matter that is left to the discretion of the board of supervising inspectors of steam vessels, I know not. If it is, it is certain that sufficient care has not been given to the subject, which is a most important one, and cannot be remedied, any too soon. The style of davit most used today, and with which all old steamers are equipped, and many of the new ones recently built and now building, is so con- structed that in order to swing the boat outboard, it is necessary to turn first one crane and then the other, after slacking up the guys. To stay the cranes after the boat is swung out, the guys must be tautened up again. This often causes delay and confusion at a most critical time and results in serious loss of life, which could be avoided by the use of the style known as the Malony davit, the patent of which I am of the opinion has expired. With this style the boat rests in the chocks outside of the cranes. To swing the boat clear of the side, the cranes are pitched for- ward and are stayed by the slots through which they pass, thus avoiding the delay and confusion that attends the process of lowering a boat with the old-fashioned style of davit. It would seem that the selection of the style of davit is left entirely to the designer of the vessel, whose knowledge and experience in the use of and the necessity for the proper means with which to swing! ships' boats is generally rather limited. Such important matters should be decided by those who from experience have a better knowledge of the need and use of such appliances. "When statute 4488 was enacted the best detaching apparatus known at that time is described and embodied in the statute as follows: 'Shall have the life boats required by law provided with suitable boat disen- gaging apparatus so arranged as to allow such boats to be safely launched while such vessels are under speed or otherwise, and so as to allow such disengaging apparatus to be operated by one person, disengaging both ends of the boat simultaneously from the tackles by which it may be low- ered to the water.' Since the enactment of this law other devices better adapted and more reliable have been invented. The board of supervising inspectors claim the wording of the statute prohibits them from adopting any other good device, no matter whether it is better or not, and that they cannot approve or enforce the use of any other. If this is the case, which is doubtful, the quicker statute 4488 is amended the better it will be for the public who travel by water. Repeal this worthless feature of the statute and the heart-rending accounts caused by the inability to lower and detach the boats in time of disaster will be of less frequent occurrence. If the laws governing these matters are such as do not admit of enforce- ment, then change them so that they may be enforced, and. if those whose duty it is to enforce the laws fail to suggest and seek necessary changes, they should be censured and held accountable to the proper authority. If they are incompetent in this regard, competent men should be ap- pointed. They should be men who by practical experience are able to determine what is best and then act without fear or favor. They should be up to date men, familiar with all appliances for modern steamers and independent of all political iufluences." Mr. Winfield Davidson, civil and mechanical engineer of Rockville Centre, L. I., says in a letter to Messrs. Cole & Kuhls of Brooklyn, N. Y.: "Your seam paint and elastic seam composition is all you claim for it. I used it in overhauling my launch and a season's test proves it greatly superior to putty. I used it in two particularly bad seams, in which I had in vain tried to make putty stay, and on examination found that it had not the least sign of cracking or falling out. On either old or new work I shall certainly use it in the future, and have no hesitation in recommending it to any one." DEARING WATER TUBE BOILER. _ For seven years past the Dearing water tube boiler has been in use in different parts of the country, largely on steam vessels of the great lakes, but the manufacturers have not tried to push it into favor. They have been concerned with its practical development, but now that their efforts on that score have resulted in an unbroken list of satisfied custom- ers they have prepared for the construction of the boiler on a very large scale. A small book dealing with this boiler, which has just been issued from the office of the company--Dearing Water Tube Boiler Co., Detroit, Mich.--is a model of neatness and clearness, both as regards the illustra- tions and the descriptive matter. Construction of this boiler, the manu- facturers say, has been made to conform with important requirements, and on this score they make the following claims: "First--A perfect circulation in all its parts; no conflicting currents, as all passageways through the boiler are so designed that the circulation is continuous and uninterruptedly in one direction. The importance of perfect circulation in the water tube boiler cannot be over-estimated. We have seen water tube boilers operated at a moderate rate of duty give fairly good results, but the moment they were crowded a little, the circulation was found to be insufficient to prevent the tubes most ex- posed to the fire from overheating. When such overheating occurs, the life of the tube must be short, and the common result is the bursting of the tube, with the consequent delay and trouble in making repairs. "Second--The use of such materials as practical use has shown to be the most suitable for the duty required. "Third--Settling chambers, in which the action of the water in cir- culating deposits the impurities of the water in stich a way that such impurities may be readily removed by the use of a blow-off pipe. "Fourth--The proportioning of heating surface so as to get the best' results obtainable, and the placing of heating surfaces practically at right angles to the travel of the heat rising from the grates, by which arrange- ment the currents of heat are broken up and distributed through the generating tubes in such a way as to thoroughly absorb the heat into the water and thus secure great fuel economy. DEARING WATER TUBE BOILER, BACK VIEW. "Fifth--Steam dome properly proportioned, giving ample capacity for steam room, and sufficient water surface to allow the rising steam to easily separate from the water, thus giving the boiler a steady steaming capacity and a steady reliable water level, preventing priming, and in connection with a system of baffle-plates, dry pipes and super-heating surface, insuring perfectly dry super-heated steam. "Sixth--A construction so much stronger than the actual require- ments that the danger of rupture of any of the parts is practically done away with, and at the same time so arranged that if a rupture should occur it would be confined to such a small part or section that it could not produce an explosion and could be readily replaced. i "Seventh--A construction which, in the event of repairs being need- ed, does not require the use of special tools, expert workmen, or material not easily obtained." A back view of the boiler is presented herewith. On page 24 a front view is shown in the company's advertisement. The boiler consists of a cylindrical steam drum or separating chamber, connected at each end to the tubular base or water leg by vertical pipes of ample area, which together form the frame of the boiler. The generating tubes are placed at a sufficient height above the grates to form the furnace or combus- tion chamber, and each section forms an unobstructed passage between the base pipes and the steam drum. The grates are placed at the level of base pipes. The economizer or feed water heater and the super-heating tubes are placed above the generating tubes so as to intercept the heat rising from the furnace, which heat would otherwise be wasted by passing into the chimney or smoke pipe. The whole boiler is preferably encased in masonry for stationary work, and in a suitable asbestos lined metal case for marine use or where the boiler it intended to be portable. The North German Lloyd liner Kaiserin Maria Theresa, which ar- rived in New York a few days ago, was formerly known as the Spree. She was in the hands of the ship builders for many months and has been practically rebuilt. She has been changed from a single-screw 18¥%-ktlot boat to a twin-screw craft, with triple expansion engines, capable of de- veloping a speed of 21 knots. Her length has also been increased 70 feet, and her beam to correspond. The Hamburg-American line is now engaged in the construction of twenty-two new steamships. The total cost of these vessels will be about $11,000,000, and they will add 150,000 tons to the tonnage of the company, which at the end of last year was 418,812 tons, represented by seventy-six vessels. Nearly all of the vessels will have twin screws. Some of them are to run between Hamburg and Philadelphia and Baltimore. coe