388 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[NOVKMBER, 



torn the upper portion, whicli is round, floats at the level of the higher part 

 of the water, and is pressed doivn by the bow of the vessel in passing, and 

 when it has passed, rises to its former position. 



" Experimental Ini/itiri/ into the Strenytti of iron, with respect to its ap- 

 plication as a Substitute for IVood in Ship-ljuitdini/." By Mr. Fairbairn. 



The number of vessels which of late years have been made entirely of iron, 

 and the probabihty of the greatly extended use of this metal in ship-building, 

 renders it desirable to attain additional knowledge as to its power to resist 

 these strains to which it is subjected, in its appUeation to the purposes above 

 stated. Mr. Fairbairn's experiments have convinced him, that in proportion 

 as the public become better acquainted with the valuable properties of this 

 material, and its fitness for almost any purpose of naval architecture, they 

 will be convinced that it is safer, and, perhajis, more duralile tlian timber, 

 and that confidence in it will be completely established. To meet the re- 

 quirements for this purpose, the following series of experiments have been 

 undertaken, and in a great measure completed. Part only, however, could 

 at present be laid before the Section. 1st. A eries of experiments on the 

 strength of plates of iron, as regards a direct tensile strain, both in the di- 

 rection of the fibre and across it. 2ud. On the strength of the joints in 

 plates rivetted together, and on the best modes of riveting. 3rd. On the 

 strength of the various forms of ribs or frames used in ship-building, whether 

 wholly composed of iron, or of iron and wood. 4th. On the resistance of 

 plates to compression and concussion, and on the power necessary to burst 

 them. The experiments were superintended by Mr. Ilodgkinson, to whom 

 Mr. Fairbairn acknowledged himself indebted for many of the results. 



On Strength of Iron Plates. — In these experiments all the plates were of 

 uniform thickness. Their ends had plates rivetted to them on both sides, 

 with boles bored through them perpendicular to the plate, in order that they 

 might be connected by both, with shackles to tear them asunder in the 

 middle, which was made naiTower than the rest for that purpose. The 

 results were as follow : — Mean breaking weight in tons per square inch, when 

 drawn in the direction of the fibre. 



Tons. 



Yorkshire plates 25-77~l 

 Do do. 2276 



Derbyshire do. 21-68 ^ Mean 22-52 tons. 



Shropshire do. 22-83 ) 



Staffordshire do. 19-56 J 

 Mean breaking weights in tons per square inch, when drawn across the 

 fibre : — 



Yorkshire plates 2 7-49 ~] 

 Do. do. 26-04 



Derbyshire do. 18-65 j. Mean 23-04 tons. 



Shropshire do. 22-00 I 



Staffordshire do. 21 -01 J 

 The foregoing experiments show that there is little difference in the strength 

 of iron plates, whether drawn in the direction of the fibre or across it. Mr. 

 Fairbairn then gave the results of a long series of experiments on the strength 

 of riveted plates. The same description of plates was here used, as in the 

 previous experiments ; the plates were however, made wider than the former, 

 in order that they might contain (after the rivet-holes were punched out) 

 the same area of cross section as the previous ones. Mean breaking weights 

 in pounds, from four plates of equal section, rivetted by a single row of 

 rivets ; — 



20127T 



18982 1''^'"='" '8^90 lb. 



I9147J 

 The mean breaking weights in pounds from four plates of equal sections to 

 the last, but united with a double row of rivets : 



22699T 



23371 I iiipan ooof.Q 11, 

 20059 f *"^^" —^•'^ '"• 

 22902J 

 Whence the strength of single to double riveting is as 18590 ! 22258. But 

 from a comparison of the refults taken from tlie whole experiments, the 

 strength derived from the double rivetted joints was to that of the single as 

 250.3(1 ! 18591, or as 1000 to 742. Comparing tlie strength of plates alone 

 with that of double and single riveted joints, Mr. Fairbairn gave their relative 

 values as under : — 



For the strength of the plate 100 



For that of double riveted joints 70 



And for the single riveted joints 56 



Hence the strength of plates to that of the joints, as the respective numbers, 

 100, 70, and 56. Mr. Fairbairn then gave a table containing the dimensions 

 and distances of rivets for joining together ilifferent thicknesses of plates. 



A discussion ensued as to the comi)arative strength and safety of iron 

 boats. Mr. Fairbairn stated, that from the manner in which the shcithing 

 is rivetted, the whole vessel becomes one njass; and though he did not come 

 forward as the advocate of iron against wood, be would state that be con- 

 sidered iron as one-third stronger than wood, weight for weight. — Mr. Gran- 

 tliara knew iron boats that had lasted 28 years in fresh water. — Mr. Taylor 

 built an iron boat for a canal in 180.'), and it was now in good condition. — 



Wheal Vor, Borlase's engine. . 

 Fowey Consols, Austin's . . . . 

 Wheal Darlington Engine . . 

 Cbarlcstown United Mines . . 



Mr. Mallctt had found, from bis experiments on the action of sea water upon 

 iron, that the duration of a half-inch plate in sea water would be about 100 

 years. 



Mr. Ilodgkinson read a paper " On the Strength of Pillars of Iron." This 

 was an abstract of a paper by Mr. Ilodgkinson. read at the Uoyal Society, of 

 which we gave an abstract at the time. — (See Journal, No. 34, page 248.) 



Mr. Fairbairn " On raising JTater from Low Lands." The commissioners 

 for draining the Lake of Haarlem having aj)plied to Mr. Fairbairn on the 

 subject, he proposed a method where the water is raised by a large scoop, 

 which rises on the descent of a weight, which weight is raised by steam 

 power, on the Cornish principle. It is calculated to raise 17 tons at each 

 stroke. Mr. Fairbairn cxhiljited a model in illustration. 



Mr. Taylor mentioned, that he had that morning received a letter from 

 Mr. Enys, stating that commissioners from the Dutch government had visited 

 Cornwall, to ascertain the duty done by the Cornish engines. Several ex- 

 periments had been made at their request, and the following was the result. 



Feet stroke. Lifted one foot. 



80 in. single 8-0 123,300,5931b. 



80 „ 9-0 .... 122,731.766 



80 „ 8-0 78,257,675 



50 „ 7-5 55,912,.392 



Ditto Stamping engine 32 hfting 66 stamps 60,525,000 



Wheal Vor, ditto 36 dble. lifting 72 stamps 50,085,000 



Mr. Glynn stated, that by a scoop wheel 25 feet diameter, and 80 horse 

 power, used by him in Lincolnshire, 4a tons of water were raised in a second, 

 the difference of level being about five feet. 



Mr. Hawkins exhibited a Model of a Railway and Carriage, recently patented 

 by Mr. Rangeley, and by him called the Safety Rotation Railway ; which is 

 an inversion of the ordinary construction, inasmuch as wheels are made to 

 revolve on fixed bearings, placed in two parallel lines along the road ; and 

 the carriage, without wheels, is built upon a pair of running rails, carried 

 along upon the pcriplieries of the train of w heels kept in revolution by steam- 

 engines fixed at every mile or two of the road. It is intended to have the 

 wheels three feet diameter, and three feet apart, which will give 1760 wheels 

 on a mile. They are to be driven by a succession of endless bands, one band 

 in every case passing around two pullies attached to every two contiguous 

 wheels. The carriages are designed to hold forty passengers each, with their 

 luggage ; the whole, including the carriage, not to exceed five tons : the run- 

 ning rails always to hear on eight or teu wheels, so that no wheel shall have 

 to support more than about ten or twelve hundred weight. The wheels, 

 therefore, need not weigh more than half a hundred weight each, to be suffi- 

 ciently strong for supporting the carriage. It is found by experiment, that 

 three ounces suspended from the periphery of such a wheel, causes it to re- 

 volve. Any weight that sets a wheel in motion, will, if continued, cause the 

 same to revolve with accelerated velocity, until the resistance of the atmos- 

 phere becomes equal to the accumulated force, after which, a steady speed 

 will be kept up. It is inferred from observation, that the w heels driven with 

 a continued force of three ounces each, would acquire a constant speed of 

 about thirty miles an hour. It is also ascertained from experiment, that 

 eight pounds would draw a ton weight on four three-feet wheels running on 

 level rails, and thus that a force of forty pounds would draw the carriage. 

 The following table is constructed from data, by which it is found that seven- 

 teen horse power of steam-engine is required to turn each mile of wheels, and 

 two horse power to drive each carriage. The power to turn the wheels, is 

 neither increased by additional carriages nor by acclivities; each carriage 

 added, taking only two horse jiower more to carry it along upon a level ; and 

 an acclivity of 1 in 180 doubling, 1 in 90 quadrupling, and 1 in 45 octupUng 

 oidy the tractive force, without in any case requiring more than the seventeen 

 horse power to turn the wiieels. 



Tlie Brilituniii.— This steamer has brought to Havre frnm London an iron 

 steamer in ,372 pieces. The vessel, which is ilestired for llio Lake of Gi'neva, 

 will be 135 feet long, and these materials are to bo transpined ihiiber lurib- 

 uilb. 



