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Performance of the steamship North Carolina
Performance of the Slea~nship 2¢'orth Carolina.
395
tpplieations of power in the propulsion of vessels, which are, practically, novelties. Whether they can ever be infrodueed in the Eastern naviga. hie rivers must depend on the speed ~hieh may be attained herealter. For marine purposes, we should be disposed to doubt their applicability, and fi)r inland l?eighting boats, which have, in many cases, to pass through canals, the side screws would be out of the question. It is possible that the large stern screws might be applied to canal boats, if made of small pitch, so that the water would not be too much disturbed laterally. As yet, the vessels driven by the new screw, have not attained any greater speed than the average ol' propellers now in use, nor are the data of sufficient accuracy to warrant us in staling that much reduction in slip is etl~ected. The slip in propeller steamers t.eed not exceed 15 to 18 per cent. in average sea weather, when the pitch does not exceed 1~. limes its diameter ; a proportion which may readily be maintained tbr any speed (within the ordinary limits) by gearing the propeller. Wehope, however, to hear further accounts from theiake engineers of their propellers, with accurate data on which to base a comparison. M. For the Journal of th(; Franklin Institute.
Pelforrnance of the Steamship 3~%'th Carolina. The loss of this ship off Holyhead, in consequence of having been run into by the Barque Robert, has been retmrted in ~he daily journals, but her perfimnance ought to be recorded in order that, taken in connexion with the diu,ensions of her hull and machinery, (already given in this Journal Vol. xxvm, Third Series, p. 411,) it may add to our experience in steam navigation. The vessel was originally buih for the coasting trade, and speei~lly modelled and designed lbr light draft of water. She had e n o f mous carrying capacity, was of great breadlh compared to her length, and intended as a freighting steamer exclusively. After two trips to Wilmington, N. C., in which she performed well, it was determined to send her to Liverpool for sale or a charter. She was accordingly fully decked over between her poop and tbreeast]e, and was despatched, very deeply loaded, (to 14 feet drati) from Philadelphia early in February. It was found, in going down the river, that she steered badly, but this was attributed to improper trim, inasmuch as she had previously steered remarkably well; aeeordingly she proceeded to sea, encountered extremely severe weather for several days, in which she was found completely unmanageable under sail, and was therefore propelled exclusively by her machinery. At length, when five days out and oil" HaliIhx, the bad weather continuing, and having been strained about her upper works, it was deemed advisable to put back, still under her machinery only, when, within 100 miles of the Delaware Breakwater, t w o blades of her propeller broke oft, and she came in with the remaining one. Arrived in Philadelphia, she was taken on the dock, additional keel and a fore f~ot put on, her rudder enlarged, her upper works refitted, and the "~hole hull reeaulked, it lteing found that her hull was as strong as when built ; a new propeller was put on, (differing from
.~lechanlcs, Physics, and Chemistry.
396
the former in being but 15 feet pitch instead of 16.~ feet,) and she again departed tbr her deslination, leaving the Breakwater at 1 P. M., ~lareh '23d, loaded to 13} feet at't~ 12~ teet forward. On the passage sheeneountered some severe weather, but pursued her course without interruption lilt within six hours run fl'om Holyhead, at 3 A. ;M., April 8, when run into as betbz'e mentioned, just abaft the fore chains; s h e sunk in seven minutes, giving the crew barely lime to save 1hemselves, tlad her voyage been completed it wouht have been made, allowing tbr dillbrence of longitude, in 15 days 9 hours from the Breakwater, which is 3200 miles run, giving a mean speed of 8~ ,1 knots an hour. At l~er dratt, hefore leaving porl, her displacement was 1195 tons. The consumplinn of coal averaged 12 tons a (lay or 1120 pounds an hour. Her engine averaged 26 revolutions, or 69~ of the propeller per minute, giving 17{ per cent. slip. Slcam averaged "23 pounds, cutting ofI'at half stroke; w,::uum 26} inches. The boilers made steam as freely on the last day as on the first, and with any head wind (to improve the dratt) furnished more than the engine couhl use. The advantages 1o be derived from large boiler surface, can scarcely he overrated. To this, principally, mnst be altributed the economy it) coal of the A~orth Carolina, which may be stated thus : 1195 tons displacement, propelled at the rate of 8~ knots an hour, (in an average of all weathers,) one knot by the consumption of i g&o=,13~ pounds of coal. It should not be forg~)tten, that the true index of capability in steamships is to be tbnnd in the number of tons displacement, driven at a given speed over a giren space, by the consmnption of one pound of coal; and, it appears, by certain recent articles in the English journals, that Ibis practical question is attracting the attention of steam engineers on the other side of the Atlantic. The great improvements in Cornish engines were brought about by comparison of the " d u t y " pertbrmed ; and a similar comparison of ocean steamers would tend to wholesome competition on the part of both ship builders and engineers. M.
On Steam Boiler Explosions and the Explosive Force of tlighly Ileated Water.* By Jon~ SPewErs, Assoc. Inst. C. E., Great Weslern Railway, London.t" (Continued from page 343.)
3. Tile explosion of the "Goliah," locomotive boiler, when running on the South Wales Railway, in 1850, with nearly similar results to that of the " Irk. " The inner copper fire-box was forced down ; the engine broken fi'om the tender, was raised in the air, turned end over, and carried to some distance. The engine had descended one incline, and was ascending another, when the explosion occurred. The descent would be affected wifl~ little or no steam, but which would be turned freely on to effect the ascent, causing an agitation in the boiler, and a rupture ~' From the London Mining Joqhrnal, November, 1854. Read at the British Association Meeting, Liverpool, September, 1854.
395
tpplieations of power in the propulsion of vessels, which are, practically, novelties. Whether they can ever be infrodueed in the Eastern naviga. hie rivers must depend on the speed ~hieh may be attained herealter. For marine purposes, we should be disposed to doubt their applicability, and fi)r inland l?eighting boats, which have, in many cases, to pass through canals, the side screws would be out of the question. It is possible that the large stern screws might be applied to canal boats, if made of small pitch, so that the water would not be too much disturbed laterally. As yet, the vessels driven by the new screw, have not attained any greater speed than the average ol' propellers now in use, nor are the data of sufficient accuracy to warrant us in staling that much reduction in slip is etl~ected. The slip in propeller steamers t.eed not exceed 15 to 18 per cent. in average sea weather, when the pitch does not exceed 1~. limes its diameter ; a proportion which may readily be maintained tbr any speed (within the ordinary limits) by gearing the propeller. Wehope, however, to hear further accounts from theiake engineers of their propellers, with accurate data on which to base a comparison. M. For the Journal of th(; Franklin Institute.
Pelforrnance of the Steamship 3~%'th Carolina. The loss of this ship off Holyhead, in consequence of having been run into by the Barque Robert, has been retmrted in ~he daily journals, but her perfimnance ought to be recorded in order that, taken in connexion with the diu,ensions of her hull and machinery, (already given in this Journal Vol. xxvm, Third Series, p. 411,) it may add to our experience in steam navigation. The vessel was originally buih for the coasting trade, and speei~lly modelled and designed lbr light draft of water. She had e n o f mous carrying capacity, was of great breadlh compared to her length, and intended as a freighting steamer exclusively. After two trips to Wilmington, N. C., in which she performed well, it was determined to send her to Liverpool for sale or a charter. She was accordingly fully decked over between her poop and tbreeast]e, and was despatched, very deeply loaded, (to 14 feet drati) from Philadelphia early in February. It was found, in going down the river, that she steered badly, but this was attributed to improper trim, inasmuch as she had previously steered remarkably well; aeeordingly she proceeded to sea, encountered extremely severe weather for several days, in which she was found completely unmanageable under sail, and was therefore propelled exclusively by her machinery. At length, when five days out and oil" HaliIhx, the bad weather continuing, and having been strained about her upper works, it was deemed advisable to put back, still under her machinery only, when, within 100 miles of the Delaware Breakwater, t w o blades of her propeller broke oft, and she came in with the remaining one. Arrived in Philadelphia, she was taken on the dock, additional keel and a fore f~ot put on, her rudder enlarged, her upper works refitted, and the "~hole hull reeaulked, it lteing found that her hull was as strong as when built ; a new propeller was put on, (differing from
.~lechanlcs, Physics, and Chemistry.
396
the former in being but 15 feet pitch instead of 16.~ feet,) and she again departed tbr her deslination, leaving the Breakwater at 1 P. M., ~lareh '23d, loaded to 13} feet at't~ 12~ teet forward. On the passage sheeneountered some severe weather, but pursued her course without interruption lilt within six hours run fl'om Holyhead, at 3 A. ;M., April 8, when run into as betbz'e mentioned, just abaft the fore chains; s h e sunk in seven minutes, giving the crew barely lime to save 1hemselves, tlad her voyage been completed it wouht have been made, allowing tbr dillbrence of longitude, in 15 days 9 hours from the Breakwater, which is 3200 miles run, giving a mean speed of 8~ ,1 knots an hour. At l~er dratt, hefore leaving porl, her displacement was 1195 tons. The consumplinn of coal averaged 12 tons a (lay or 1120 pounds an hour. Her engine averaged 26 revolutions, or 69~ of the propeller per minute, giving 17{ per cent. slip. Slcam averaged "23 pounds, cutting ofI'at half stroke; w,::uum 26} inches. The boilers made steam as freely on the last day as on the first, and with any head wind (to improve the dratt) furnished more than the engine couhl use. The advantages 1o be derived from large boiler surface, can scarcely he overrated. To this, principally, mnst be altributed the economy it) coal of the A~orth Carolina, which may be stated thus : 1195 tons displacement, propelled at the rate of 8~ knots an hour, (in an average of all weathers,) one knot by the consumption of i g&o=,13~ pounds of coal. It should not be forg~)tten, that the true index of capability in steamships is to be tbnnd in the number of tons displacement, driven at a given speed over a giren space, by the consmnption of one pound of coal; and, it appears, by certain recent articles in the English journals, that Ibis practical question is attracting the attention of steam engineers on the other side of the Atlantic. The great improvements in Cornish engines were brought about by comparison of the " d u t y " pertbrmed ; and a similar comparison of ocean steamers would tend to wholesome competition on the part of both ship builders and engineers. M.
On Steam Boiler Explosions and the Explosive Force of tlighly Ileated Water.* By Jon~ SPewErs, Assoc. Inst. C. E., Great Weslern Railway, London.t" (Continued from page 343.)
3. Tile explosion of the "Goliah," locomotive boiler, when running on the South Wales Railway, in 1850, with nearly similar results to that of the " Irk. " The inner copper fire-box was forced down ; the engine broken fi'om the tender, was raised in the air, turned end over, and carried to some distance. The engine had descended one incline, and was ascending another, when the explosion occurred. The descent would be affected wifl~ little or no steam, but which would be turned freely on to effect the ascent, causing an agitation in the boiler, and a rupture ~' From the London Mining Joqhrnal, November, 1854. Read at the British Association Meeting, Liverpool, September, 1854.