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ge HREE SISTERS.” m, N.A., Clevelana, 0.) 1k it is ways an interesting study to carefully Lthin i compare the ideas of eminent men, even though such ideas be apparently visionary, but when great projects carried into practical effect through sturdy geniuses possessed with the courage of their convictions, so that huge machines are brought forth it may be in startling 1 deur, as instanced by the Biffel tower and the bridge, with 51,000 tons of steel composing its structure—a portion of the latter with one of its girders inverted and placed on top of its sister girder as it now lies, being not very dissimilar to the tower, either in dimensions, contour or weight. When ideas become solidified in any such degree as these, a comparison of their merits or demerits cannot but be both interesting and instructive. !In the following lines, which I trust may be absolutely free from personalities, I may pre- mise that in each of the great shipbuilding yards on the northwestern lakes there were several officials who had something to say, and there were others who were more unhappily environed by having to say something. Further, I shall not trouble my readers by attempting to apportion the precise quotum of merit due to the sev- eral great achievemerits referred to, but will say of each, “A mighty leap was this; no transient stride; a great conception of still greater brain.”’ About one year ago tenders were solicited by one of our oldest and richest shipping corporations for three steel steamships, to be of thesame dimensions, tonnage, horse power and arrangements of hatchways, gang- ways and cargo gear. Now all this being so, one would imagine, or almost aver, that three very similar steamers would be produced, in fact, three sister ships might have been looked for, but the imagination being by no means an exact faculty, and being eminently un- unfit for gauging the acts of men, particularly engin- eering men, let me say at once that the imaginations or lucubrations of the gentlemen whose work we are dis- cussing produced perhaps the most extraordinary diver- sity or charming variety in detail of construction I have ever known to be reared on so circumscribed a base. Of course in each of the great shipyards where the ‘“Phree Sisters’? were constructed} there were general managers or superintendents—good practical men, every one of them, and possessed of no little knowledge of the theory of naval architecture and mechanical en- gineering. MopEr.—One gentleman said that a steamer ought to float above water as much as possible, and he would keep the sea off the decks. Another said he wished the sea to come up the side as it would then be less effective in causing the ship to roll, but in one instance the side was beautifully arranged to induce the sea to come up whilst the bow was just as carefully designed to cause the sea to stay down. These diverse theories were somewhat difficult to reconcile with talented experi- ence, One builder made his vessel about straight on the deck at the center, which gave a slight rise at the ends, the other ships were straight on the deck at side line, which gave a slight drop at the ends. One naval architect said in connection with these steamers, that as regards sea-going qualifications,we had not improved in our models for hundreds, or perhaps thousands of years and the ancients always gave their vessels some sheer. The other gentleman remarked that of all the foolish things he ever saw it was giving a deep lake steamer sheer,there was no sense in it,these steamers always sailed with fifty or sixty per cent. surplus buoy- ancy whilst the average tramp crossed the ocean with twenty-five or thirty per cent., in which case sheer did help them, both when “‘head-to’’ and in running, our boats seldom, or ever, ship green seas and as we require them to carry dead-weight, every ton in weight we can cut off the vessel, whether it be off their sheer or other part, means a ton added to the dead-weight ability. As to looks, I have always said that any feature of a machine which adds to its efficiency and economy in working without increasing the first cost cannot be ugly. This trio, however, could not be brought to agree upon a uniform price, as each one appeared to believe that his production would be worth much more than his confreres, indeed the contractor who received the low- est price talked as if his yessel was worth about as much as the other two and without doubt this was a very ex- pensive steamer to build. FrameEs.—The framing of the 3 ships were very much alike, though one shipbuilder reduced the spacing from 24 inches at the bluff of the bow to 18 inches at the stem, another did not do this, one shipbuilder carried his re- verse frames up to the upper deck, the others did not, One continued the frames up to the top of forecastle, the THE MARINE RECORD. others added the forecastle frames in separate lengths and secured them to the main deck by brackets. BEAMS.—One said the beams should be deep, and he therefore placed them 4 feet apart, another said they ought to be spaced only 2 feet apart with thin decks, one used steel angles for his purpose, another used T bulbs, the third adopted | bulb angles. BALLAST-TANKS.—As regards the method of making the water-tight connection between the tank top and the bilge, one man in effect said that the error of cut- ting the frame to secure this connection was most flagrant and ought not to be allowed under any circum- stances. The other replied that soft “stops” around the frame were so abhorent to his ideas of good me- chanical construction that he could not conceive how shipowners could be so blind to their own interests as to accept such an arrangement—or rather, derangement —at any price. Howcould any one compare canvas, red lead or buggerum with solid metallic calking? The third said, if they would only make their tank and bilge brack- ets as he made them, it would matter little whether the frames were cut or not. Dovsik Borroms.—Another friend said that {he longi- tudinal system was the only proper method of construc- tion. Others said that whilst that system was more ex- pensive than the ordinary transverse floor, with top, fore and aft girder, it was also more difficult to repair. One said the tank top should be lower at the centre line than at the bilges; others said that was absurd, the tank top should always be higher at the centre than at the sides. One placed Z irons on top 4 feet apart; the other placed angle irons'2 feet apart, while yet another dispensed with both and fitted wood bearers on top. Burr Srraps.—One of my friends, whilst riding with me, remarked that he could never understand how any man who understood his business could be satisfied with single butt straps. Where severe stresses were expe- rienced he would have double sheer both top and bottom. Another said he saw no sense in doing this, for he had ample sectional area of rivets without double sheer. A third remarked that he made his double bottom so strong that the top sides would be fractured long before the bilge would give way; therefore, he saw no reason for extra riveting and double straps at the bilge. ENGINES.—The diameters of the several cylinders were not very diverse, though two makers made their low-pressure engine two inches greater in diameter than the other. These gentlemen did this because the low- pressure cylinder limits the power of the combined en- gines, or, as he would have expressed it, in other words, because the energy exerted by a fluid depends on the change in pressure and volume which it undergoes, not on the number and arrangement of the cylinders. the power or consumption of fuel; this depending 0 diameter of furnace, in the absence of forced gentleman made his low pressure cylinder two ir less than the others, and his stroke two inches less’ rather the heat, which represents the power, w: contained in the boilers; but why this vessel have a larger wheel than the others I could not < tain, except that this gentleman would never acknowl- edge the assumed fact of being “‘ over-screwed,”’ an ie maintained that what appeared to be lost in capacity cylinders would be more than compensated by the extra revolutions of his engines. I said that*l could un stand that, if his wheel also had been smaller than the others, but as it was, I gave it up. : ne VaLvE GEARS.—One gentleman said, if yon want a perfect indicator diagram, you must adopt the Joy valve gear or other similar gear, and I always fit this on my high pressure cylinder. Besides this most important desiderata, I also gain the space required by two eccen-— trics, and increase the length of my crank pins or main bearings to that extent, and if this is not admitted to be an advantage, I will appeal to any old sea going engi- neer, and ask him how he felt when off a lee shore on a stormy night, with his bilge-water gaining on him, coal in bunkers very low, with main bearings doubtful and a hot crank pin to keep him liyely. The other maker said that might be all very true, but he had found the double eccentrics and Stevenson’s link motion very faithful old servants, and if anything serious happened to one eccentric there was always the second to fall back upon; besides it mattered little whether the steam was evenly distributed in the high pressure cyl- inder or not, for the low pressure was not only the measure of the powet, but the economy of the whole machine depended entirely on ti#e last step in expansion, Two makers made their boilers 14 feet diameter and 12 feet in length, and the furnaces 44 inches in diameter. ‘The third maker said those boilers were too short for the coal in this country and the grates were too small ; a large furnace was the most important feature for an economical boiler in the absence of forced draft. Mr. Hammond says 150 cubic feet of air is required for the combustion of one pound of coal, for when coal is burnt with insufficient air, carbonic oxide is produced and to convert this into gas not less than 200,000 cubic feet of air to 10,000 feet of carbonic oxide must be admitted, or say 20 tol, or not less than 100 cubic feet to each pound of coal.. The other engineers maintained that the fur- naces were large enough, and they did not believe in crowding their boilers with too large furnaces and too many tubes, for nothing is of greater importance than free circulation of water, and that could only be obtain- ed by allowing plenty of space between the rows of tubes and between the tubes, the furnaces and the shell of boiler. . This gentleman’s efforts were mainly direct- ed towards the saving of fuel. For my own part I may say that I look upon extraordinary results in economy of consumption of fuel with suspicion as regards the general economy or success of a steamer in the matter of working expenses, and it should seem from the fol- x i u Bites x LINE “THREE SISTERS.” Mahoning, Codo and Schuylkill—by Joseph R. Oldham, N. A. a w oS [el The ‘4 a @ | Be ee 9 5 x Engines = He 28 Pt Be | ag a3 g8} of QD Boilers 6 “Three 8 susan bad 2 2. Ey a si a 28 |p ee By 2 Propeller & Sisters” |] |B) | 80) 2° |ES jem [gf | Diameter | | || Wheels. | & Food Po fof [So | Me Soe Boal Bilis @plinderss ye) pay Ore & DW\DW Tons|® Rol Ew ‘ons| Feet.|Feet.| Inches. In. | Feet. | Feet. | Feet. | Feet. |Sq. ft. 1.681 | 2.284 | 3,060 | 16-0 | 5-8 20—32—52 42 14 12-6 E A 2 2, 2 13- 1.730 | 2.253 | 3,020 | 16-0 | 5-8 20—32—54 44 14 12-0 | 12-6 rar s 2.320 | 2.320 | 2,970 | 16-0 | 5-634} 20-3254 | 42 14 | 12-0 | 12-6] 15-9] 48 As regards the position of the cylinders, one maker placed the high pressure aft, the low pressure forward, and the intermediate pressure cylinder between the two, another maker placed the low pressure aft and the intermediate pressure forward, and the high pres- sure between the two, and made his diameters such that with a cut off from fifty to sixty per cent. the theoretical absolute terminal pressure in the low-pressure cylinder would not exceed 10 pounds per square inch. He also maintained that the low-pres- sure engine was the source of the greatest inefficiency and should be relied on to complete the economy of the whole machine. As to sequence of cranks, one maker arranged the high pressure crank leading, intermediate crank following, and low pressure crank last. Another maker placed his intermediate engine crank last, be cause, if the low pressure crank be arranged last, it results in excessive variation in the receiver pressure, greater range of temperatures and increased variations in initial stresses. ‘The third arrangement was intermediate crank lead- ing, high pressure following, and low pressure last. A better arrangement would have been high, low, and intermediate. Boriers.—There is no remarkable discrepancy be- tween the three sets of boilers, though one builder did make his furnaces 46 inches diameter, against 44 inches in the others. There was also a difference in the lengths of fire grates, but this did not materially affect either lowing statement of the gross disbursements of a fleet of steamers engaged in the foreign trade, that the coal bill is but a secondary item of the working expenses in cargo steamers, andif this be so for long yoyages, it must be of still less moment on lake steamers. I do not mean by this that we should rest on our oars and remain contented with a coal consumption of 114 pounds per in- dicated horse-power per hour, but I have frequently found that when the consumption of fuel is very low, the speed of the vessel is very low, I mean unduly so, 5 Gross earnings of six tramp steamers for twelve months $350,000 EXPENDITURES OF ABOVE FOR TWELVE MONTHS. Wages and provisions., Port charges. . ae ng Stores, docking a: : 51,000 Tnstirances.9.) een 45,000 Loading and discharging 40,000 Fuel... a 35,000 35,000 - — 20,000 $350,000 i