1843.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



209 



Indian iron, although difficult to work, stood better than other kinds when 

 once reduced into form ; this he attributed to the purity of the magnetic 

 ore from which it was produced ; there was not the slightest trace of phos- 

 phorus, arsenic, or any deleterious foreign matter. He was convinced that, 

 with a mixture of Indian pig-iron (which could be produced very cheaply) 

 and Devonshire ore, by Mr. Clay's process, iron could be made of excellent 

 quality for converting into steel at such a reduced price as would render the 

 introduction of Swedish and other foreign iron unnecessary. 



Mr. Taylor believed that improvement in the quality of steel, rather than 

 reduction in the price, was the object to be sought. In the large quantity 

 used in the mines under his direction, the dearest steel was found to be the 

 more economical. He had seen as many as 12 dozen borers used to make 

 one blast hole, and unless the tools kept their points well, the labour of the 

 meu was thrown awav. 



February 21. — The President in the Chair. 



Mr. Giles presented a plan and sections of London Old Bridge, made from 

 his surveys of it in 1820, by order of the Committee of the Bridge Lands, 

 with descriptive notes. 



The plan represents the stirlings, piers, parapets, and roadway of the old 

 London Bridge, its low-water channels, called locks, with the soundings 

 through the locks. The sections represent an elevation and levels of the 

 stirlings, piers, arches, roadway, and locks, with levels of the tides observed 

 at the bridge in September and October, 1820; the datum to these levels 

 being the Trinity high water mark of London, which is recorded on a stone 

 let into the lower external wing of the Hermitage entrance of the London 

 Docks. ' 



From the plan it appears that — 



Ft. In. 

 The aggregate waterway between the piers above sterling height was 524 2 

 The width occupied by the piers .... 406 10 



Making the total length between the abutments of the bridge . 931 



The aggregate waterway below the stirlings at low-water was . 230 1 1 

 And the aggregate distance occupied by the piers and sterlings at 



low-water was ...... 700 1 



Ft. In. 

 2 



6i under ditto. 



The level of the tides shows — 



The extraordinary high-water mark of springs to be 

 The average high-water mark of springs between 



23rd September and 25th October, below bridge 

 The same above bridge . . . .12 „ 



Making the high-water of spring-tides above bridge 



l\ inches under the same high-water below 



bridge, owing to the obstruction which the piers 



presented to the tides attaining their full height 



above bridge : and this difference was found 



commonly to be 8 inches. 

 The average high-water mark of neap-tides above 



bridge was . . . . .43 „ 



And the difference of high-water of neap-tides below 



and above bridge was not observable. 

 The average level of low. water mark above bridge 



was . . . . . 14 5 ,. 



The average level of neap-tides low-water mark be- 

 low bridge was . . . .16 6 „ 

 The average level of spring-tides low- water mark was 18 9 „ 



Thus the average fall of water through the locks of the bridge at neap- 

 tides was 2 feet 1 inch, and the same at spring-tides was 4 feet 4 inches. 

 But an extreme fall of 5 feet 7 inches was observed through these locks on 

 the occurrence of a high land flood, and a spring-tide ebb. 



Having completed the surveys of old London Bridge, Mr. Giles subse- 

 quently took the levels of the tides from thence to Teddington lock, and 

 found that in the absence of high winds and land floods, the high-water of 

 spring-tide on the upper side of London bridge attained its level or height 

 at all the London bridges, also at Battersea, Putney, Kew, and Richmond 

 bridges, and at Teddington lock. 



" Account of a series of experiments on the comparative strength of solid 

 and hollow Aries." By John Oliver York, Assoc. Inst. C. E. 



The author first describes the causes of fracture in railway axles, which he 

 attributes to the sudden strains and injury produced by concussion and vi- 



1 Low-Hater mark is 17 feet 10 inches below the lower edge of this stone, 

 settled by the Corporation of Trinity House, August 1800, (39 and 40 Geo. 

 III.! cap. 17, sec. 55.) 



bration. Those resulting from concussion are chiefly ascribed to a defective 

 state of the permanent way, any sudden obstacle opposing itself to the pro- 

 gress of the train, and the severe shocks arising from the wheels coming in 

 contact with the blocks and sleepers when thrown off the line. The force 

 of vibration and its certain effect to produce fracture in a body so rigid as a 

 railway axle, is then fully explained; the evil arises from the impossibility of 

 diverting from the axle the continued series of slight blows or vibrations to 

 which it is subject, or of causing a free circulation of them through its entire 

 length, since the naves of the wheels being fixed tightly on to the axles, 

 form a point on either side for the vibrations to cease, and the particles of 

 iron composing the axle at this point become dislocated by the continued 

 and unequal strain, and ultimately break ; the same action' is described as 

 taking place in the journal of the axle, and hence the fact that an axle seldom 

 breaks excepting at the journal, or at the back of the nave of the wheel. 

 The twisting strain to which railway axles are subject is next considered, and 

 a calculation entered into, to prove that upon a circle of only a few feet in 

 diameter and assuming a first-class carriage on four wheels to' weigh six tons, 

 the strain resulting from this cause is so slight as to be unworthy of consi- 

 deration in the inquiry. The paper next proceeds to point out, how and why 

 the hollow axle is better able to resist the strains before referred to, than the 

 solid ones now in use. 



First, by the process of manufacture, by which the crystallization of the 

 iron is avoided, and it is left in a better state for sustaining sudden strains 

 and continued action. Secondly, by the position of the metal composing 

 the axle, since the comparative strength of axles are as the cubes of their, 

 diameters, and their comparative weights only as their squares, conse- 

 quently, with less weight there must be increased strength ; and thirdly, 

 that the vibration has a free circulation through the length of the axle, no 

 part being subject to an unequal shock from the vibration, and the axle would 

 therefore receive much less injury from this cause. In conclusion, it is sub- 

 mitted that a railway axle should possess the greatest possible degree of 

 rigidity between the wheels, to prevent it from bending or breaking from 

 concussion, combined with the greatest amount of elasticity and freedom in 

 the particles of iron within the axle itself, to prevent the injurious effects of 

 vibration. 



The details of a numerous set of experiments are then given, to prove the 

 superiority of the hollow axle in all these respects, the average of the whole 

 of which is thus stated. As regards rigidity to sustain a dead weight. The 

 axles being supported at the ends, and the weights applied in the middle. 



As regards its capability to resist a falling weight. 



5 cwt. 3 qrs. 6 lb. falling from a height of 16 feet ou to the centre of the 

 axle. 



As regards the elasticity and fibrous quality of the journals. 



Hollow Axle. Solid Axfe. 



Number of blows to destroy | Number of blows to destroy 



journal (average) . . 28 | journal (average) . 



Proportions of axles. 



The paper is illustrated by specimens of the broken axles, both hollow 

 and solid, and by diagrams of the mode of manufacturing the two kinds of 

 axles. 



Remarks. — Mr. Geach presented a series of specimens of ends broken 

 oft' solid axles, made by the Patent Shaft and Axle Company, Wednesbury ; 

 they have borne severally 886, 148, 293, and 278 blows of a sledge ham- 

 mer, weighing 38 lb. before they separated from the body : above twenty 

 more ends had been broken off, the weakest requiring 138 blows. The di- 

 ameter of these journals was 2\ inches. An n\le was exhibited which had 

 been bent nearly double under an hydraulic press, with a prewttre 



