1S41.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



213 



NEW FORM OF VIADUCT. 



(With an Engraving, Plate VII.) 



The accompanying drawings show a new species of viaduct that has 

 been made use of as a general design, in the parliamentary estimate 

 of a recently surveyed Hailwuy. 



Fli?. 4— Side view of the Clutch Box D. 



The principle in its simple form, i"! not new to the engineering 

 ■world, having been put into execution in the " Foot bridge over the 

 Whitadder, at Abbey St. Bathans," (see Theory, Practice, and Archi- 

 tecture of Bridges, part four,) and being commonly used in temporary 

 erections, scattblding, &c., and frequently applied in strengthening 

 various kinds of vehicles. The novelty consists in carrying out the 

 idea to the magnitude of the present rage.i 



Fig. 5— End view of the Clutch Box C 



^,--^-ijpi 



It will be seen that the system is ap- 

 plicable on a great scale, in those cases 

 only where there is a large amount of 

 headway tospare,as the efficiency of the 

 arrangement is so completely dependant 

 on the inclination of the tension bars. 

 The estimation of the strength in the 

 original furm, is a matter of great ease, 

 involving only a simple case of resolu- 

 tion of forces. 



This design is made for a single line 

 of rails only, but it would appear that 

 it might be much more advantageously 

 and economically applied to a double 

 line. 



A reference to the drawing will pre- 

 clude the necessity of any detailed 

 description, and it will be necessary 



merely to draw attention to the more important points. It will be 

 seen that the application of the tension bars is not confined to the re- 

 Fig, 6— Section of the Clutch Box C. 



-No .46.— Vol.. IV.— JoLY, 1841. 



sistance to vertical deflection, but that it is made use of in given 

 lateral strength to the main supports, (inverted tressels would perhaps 

 be the most descriptive term), their bending being prevented in one 

 direction by the transverse studs and tie-bolts, and in the other by the 

 tension of tiie iron rods. 



A weight entering upon the bridge will be pcvcoived to immediately 

 distribute its effects over the whole structure, by means of the ascend- 

 ing intermediate bars ; these bars will effectually prevent anv partial 

 deflection that might be expected to occur upon an unequal distribu- 

 tion of the load. 



It will be observed that rods are dotted in, and noted as being carried 

 to the sides of the ])iers, to prevent any lateral oscillation; little fear 

 of this however ne^d be entert.iined, as the surface exposed to the 

 wind would be so slight; nevertheless if there were any apprehension 

 of such an effect, it might be further guarded against, by a divergence, 

 of the sides of the supports, as shown by the doited lint-s at D', D', on 

 the transverse section ; and this would be done with very little diminu- 

 tion of strength. In a double line there would be no need of such 

 precaution. 



The estimated cost, including scafTulding, &c., and exclusive of 

 piers, is U/. per lineal foot; the quantities I took out myself, and can 

 bear testimony to their fulness ; the prices were given by another, and 

 were high in consequence of the difficulty of the localities ; in short I 

 believe that the above price is rather more than would be the cost in 

 average cases. With regard to the strength, I think it will be found 

 by any one who will be at the trouble to calculate it, that it is if any 

 thing greater than what is stated. 



To those with whom appearance is the main point in railway works, 

 the design will probably afford some amusement; but every one will 

 I think perceive that elegance of effect is not attempted, an economi- 

 cal and durable structure being the only object in view. 



Heruebt Spencer. 



Derby, Ma;/ 11, 1S41. 



Referctjce to Drawings. 



Fig. 1, Plate VII. is a side view of the bridge, part of the span is omitted 

 in Older that the remainder might be kept to as large a scale as the size of 

 the Journal uouUl admit. Fig. 2. is a transverse s.ection of up.e of* the sus- 

 pensions or tbe cross trusses ; and fig. 3. a transverse section of ilie centre 

 suspension or cross truss. Fig. 4, enlarged view of the clutch box D, secured 

 to tne piers. Fig. j, end view of the clutcli box C ; and tig. 6, a section of 

 the same. The three last figures are drawn to a scale of j of an inch to a 

 foot. 



CONDUCT OF THE GOVERNMENT TOWARD.S THE 

 ENGINEERING INTERESTS. 



We have, on more than one occasion, thought it our duty to call 

 the attention of our readers to the conduct which has long been pur- 

 sued by the government and the leghslature, as lo all measures bearing 

 upon tile interests of the engineering profession. We are well aware 

 that many of these measures, although weighing most strongly upon 

 the engineers were directed against other interests, and cannot there- 

 fore be considered as purposely levelled against the profession; but, 

 nevertheless, when we observe the tendency of measures inoi^ direct, 

 and the uniform tenor of tliese proceedings, we are obliged to admit 

 that either the policy or the inclination of the governing body is con- 

 stantly directed to our injury. Im whatever way we examine the mea- 

 sures affecting us we are impressed with this feeling, and now that we 

 are enabled to look back and class together isolated events, we find an 

 accumulation of evil in tbe highest degree threatening the profession. 

 On the one hand our employment is proposed to be taken from us, and 

 on the other we are to be placed under the government direction and 

 control; so thit both our moral and physical interests are equally con- 

 cerned. It is perhaps fortunate that circumstances have intervened to 

 preventevery attempt from being effi^ctive, but still a sufficient amount 

 of mischief has been perpetrated to call for the serious attention of 

 every one to the position in which he is placed. It might have been 

 well at a former period for the civil engineer to say, that afi'ects the 

 marine engineer or the capitalist and not me, or for the practical engi- 

 neer to say that has nothing to do with me, but now when we come to 

 review the whole of these proceedings we find something which affects 

 each individual branch, while there no longer remains a doubt that the 

 whole body is in danger. What engineer when he considers the seve- 

 ral government measures of the last four years can now flatter himself 

 that he is safe, and that the attack on his neiglibour is imminent of no 

 danger to himself ? Let him look at the Ten Per Cent. Deposit Clause, 

 the Irish Railway Scheme, the Steam Navigation Bill and the Rail- 

 ways Bill; let him read the speeches of ministers, the reports of con)- 

 niittees and commissioners, and the suggestions of commissioners, let 



2 G 



