180 MK. WILLIAM FAIEBAIRN ON 



These advantages are common to all countries; and now 

 that rapidity of transit has become an essential part of our 

 existence, it naturally follows that every discovery and 

 «very improvement which tends to the extension and en- 

 largement of these facilities, must prove beneficial to the 

 public, as well as interesting to the philosopher and the 

 engineer. Impressed with these views, I have endeavoured 

 to collect the results of a long series of experiments, and to 

 narrow within the compass of a few pages those labours 

 which have occupied no small share of my time and thought, 

 whilst devising means for the construction and proportion- 

 ing of the parts of a new system of bridge-building. I now 

 propose to submit these results for the consideration of the 

 Society, prefacing them by a few remarks relative to the 

 construction and other matters connected with the security 

 and permanency of this description of bridge. 



In a paper given' to- the Institution of* Civil Engineers I 

 have stated, that " every erection of this kind, having for 

 its objects public convenience and a public thoroughfare, 

 should have within itself the elements of undeniable secu- 

 rity. Bridges above all other structures should contain 

 those elements: they are the most liable to accident; and, 

 from whatever cause such accident may arise, the commu- 

 nity are equally interested in the strength and durability 

 of the structure. In attempting the introduction of a new 

 system of construction, comprising the use of a new and 

 untried material, it behoves the projector, therefore, on 

 public grounds, to be careful and attentive to all the minu- 

 tiae directly or indirectly affecting its security. In bridges 

 of the tubular construction, considerations of this kind are 

 of primary importance, as much depends not only upon a 

 Correct application of the principle, but upon the quality 

 of the material and the workmanship introduced, which, in 

 fevery case, should be of the very best description. In the 

 construction of Tubular Girder Bridges, I have endeavoured. 



