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as to reduce the percentage of hydrocar- bons to a minimum and prevent caking in the producer. In these problems there was much for the consideration of the best trained in- telligence that we possessed. In the car- go vessel, the Lord Antrim, were gas producers in which the upper part of the furnace was worked with a down draught, and the lower part with an up draught, the gas being drawn off at the center on the suction principle.. The raw fuel was introduced at the top, and was coked as it settled down towards the gas outlet; _ the hydrocarbon or tarry vapors in the meantime were either destroyed, or cofi- verted into fixed gases when _ pdssing through the incandescent fuel to outlet. There were primary and secondary hot air supplies; the latter, drawn up from the producer base, was charged with steam vapor, and gas was made on its passage through the coked fuel; the gas afterwards was thoroughly sprayed and finally cleansed in coke, sawdust or wood wool scrubbers. It was already. known that a successful bituminous coal suction producer, something on these lines, would soon be made public, In the drawings which Mr. H. Cherry had been good enough to put at his dis- posal, the cleaning of the gas was whol- ly done after it had left the producer, by means of wet coke-scrubbers, wood-wool scrubbers, and the like, but as suggested, the tar might be utilized by burning it in the producer itself, increasing the ef- ficiency and simplicity of the plant, The plentiful supply of water was a _ very great advantage in the cooling and clean- ing of the gas, for sea water would have no deleterious effect upon it; also the small quantity of steam vapor required. for its manufacture might be obtained from the same unfailing source, aid there would be no necessity to store fresh, water or filtering apparatus as was usual with steam boilers. Again, as regarded size Of fuel, a colliery owner informed him that bituminous coal could be sup- plied direct from the mines of suitable size, as was done with anthracite peas, at a slightly increased cost; or the ves- sel itself could carry its own crusher to deal with the coal before delivery into the producer hopper, | - With regard to the third difficulty-- perfect control of a gas-propelled vess3_l is our next consideration--one of the main difficulties that contronted the gas engineer in applying gas engiucs for ma- rine purposes was that of 'reversing. With small powers it was possible to re- verse by means of a reversible propeller, the engine having only one direction of rotation. There was naturally a very serious objection to putting the revers- ing gear in so inaccessible a position a¢ in the propeller, but at the same time there was undoubtedly a future for this 4 TAE MARINE REVIEW type for river and coast work, 1f made simpler and more reliable. One of the great advantages of this type in con- nection with stction gas plants, was that the engine continued to run while the vessel was being reversed, slowed down, or stopped altogether; and the advantage was this, that the heat in the producer was sufficiently maintained by the con- tinued working of the engine for the production of good working gas. The main disadvantage with these re- versible bladed propellers was a mechani- cal one, for after a spell of work the bearings in the propeller boss, in which the miovable blades were mounted, got worn, the blades lost their alignment and were liable to jam when the gear at- tempted to move them, and however great the care in design, sea water soon- er or later got within the boss and 'in- jured the gear. .Mr. Vennell Coster showed a new type of reversible propel- ler in which the gear was designed to work in the water, It was, he said, of so simple a construction (with all bear- ings of anti-corrosive anti-friction met- al), that it could with safety be applied to higher powers than those usually al- lowed in present-day practice with re- versible propellers. The blades were mounted on fixed pivots with a bearing supporting the blade where the greatest load was applied, and therefore, even if the blade was slack on its bearing, there was no fear of jamming or getting ma- terially out of line, This arrangement 1906. Vessels, Tons, DCOMan.c70 ace | 53° 5Et 658,830 Eneland: 4.445% ee . 882 ~--_:1,193,881 Peeland: ovis 28 149,860 UK, totals. oc. 00, 1480 2.002507 Colonial (ta.3540.3 ts Oy 1G 4 28982 Foreign visi ee 1,262 1,322,454 2,792 3,353,807 also made the removal of a blade and its replacement a very simple matter indeed, and it could be accomplished without docking the vessel, if light. For higher powers up to, say, 500 H. P. units there- was another system in vogue for revers- ing the propeller, viz.: A reversing gear, which might be a combination of bevel or spur gear and friction clutches, and was fitted somewhere on the propeller shaft within the vessel and in an acces- sible position. With this type it was cus- tomary when driving ahead for the bevel or spur wheels to be out of gear, These only came into operation when going. astern. There were many patented ex- amples, by well known makers, of this method of reversing, which had the same advantage as the revers'b'e, propeller in that the engine only ran in cne direction, and might continue to run whether the vessel was moving or not. But for pow- ers above 500 H. P. the gas engines 27 themselves must be made to reverse, for that dispensed with exoens've and 'coai- plicated clutches. Mr, 5. TI. Milton, a vice president of the Institution of Naval Architects, had said in connection with this matter "that marine eugineers who are used to big engines think the inclu- sion of clutches a very serious proposat; they are not used to clutches If the clutch gets out of order then the screw is done for, For sea-going shigs we want a rigid connection between engine and. screw, the engine must have direct driv: and be feversible." There were many methods of doing this. M:. Cherry, in his designs of marine gas engines, showed. one system in which he had double sets of cams and rollers, con- trolled by a reversing link, while Messrs; Crossley and Messrs. Thornycroft ro- tated the cam shafts. There was no practical difficulty in reversing the gas engine provided a sufficient reservoir of compressed air was at command. GREAT INCREASE OF TONNAGE. The ship building returns from all parts of the world show that the year has been very much busier than last year, The total output, according to our figures, consisted of 2,792 vessels of 3,353,807 tons and 3,158,664 I. H. P. This is an advance of 399 vessels, 409,877 tons and 689,159 I. H. P. The following! table shows the work of the year in the United Kingdom, the Colonies, and foreign countries: i LOO8y ie 08 | I, EP... Vessels, . fone. (1 ue. 070,431. 412 587,032 566,007 1,028,352 . 793 1,073,300 810,481 147,200 BL. M1Ad, 727° 116 288 1,845,983 1,236 . 1,805,968 1,501,859 18,305 64 10,610 5,038 1,204,286 1,003 1,127,352 962,608 3,158,664 2,303 2,043,030 2,469,505 - Owing to great:increase of business, the Bird-Archer Co. has this last wee moved its offices from 209 Washing: ton sireet to the new West Street building, at 90 West Street, New York.. The sumptuously furnished offices of suite 15 on the: twelfth floor of that building will be the future headquar- ters of this company. For the present the warehouse at 209 Washington street will be retained until completion. of the new factory and Jaboratories now 'building in Jersey City, for the manufacture of the well-known Bird- Archer boiler compounds. The com- pany has recently issued a new pamph- let relating to the causes, effects and remedies of scale, grease and corro- sion in stationary boilers, and will be pleased to forward a copy of this pub- lication to all interested. <4