278 PETER GUTHRIE TAIT 



secures. Those who wish to know its extent must read the work itself. They will 

 soon be introduced to novel forms of concentrated operators, with regard to which, 

 as I have not yet formed a very definite opinion, I shall content myself by hazarding 

 the remark that, while they are certainly powerful and eminently useful, they must 

 at present be regarded as singularly uncouth. 



Some of Tail's contributions to Nature were signed G. H., i.e. Guthrie 

 Headstone = Guthrie Tte Peter. These were always short notes, at times 

 quizzical, bearing on some passing interest. One of serious import was the 

 reference to the Tay Bridge disaster of December 28, 1879. The letter to 

 Nature (July 22, 1880) is worth quoting from. 



There are two interesting scientific questions, apart from engineering proper, which 

 are suggested by the late enquiry, although no reference seems to have been made 

 to them in the reports. 



The first is the origin of the extraordinary flash seen at the moment of the 

 downfall of the bridge by many spectators several miles away. It is scarcely doubtful 

 that an impact was the only possible cause. 



The second is the important question of the amount of wind-pressure which would 

 suffice to force a train bodily off from the top of the bridge 



The flash seems to prove that the train had been blown off the rails, and had come 

 into violent contact with the sides of the high girders. Then, and not sooner, the piers 

 were subjected to a strain they were unable to bear. 



Tail's strong objeclion lo acling as a scienlific witness prevented him 

 from appearing at the Enquiry, but this in no way interfered with his making 

 suggestions lo his old school friend Allan D. Slewart, M.Inst.C.E., who 

 had been consulled by ihe Engineer, Sir Thomas Bouch, in regard to the 

 design of the continuous girders, though nol of ihe columns whose failure 

 caused ihe calaslrophe. Several years later Tail's allenlion was called by 

 his son (ihen an Engineering Apprenlice) 1 to an official diagram showing 

 how the engine, carriages, etc. and the girders were found relalive lo ihe 

 proper cenlre line of ihe bridge, and he agreed lhal ihe upselling or derailing 

 of a second-class carriage near ihe rear of ihe train was ihe immediale cause 

 of ihe collapse of ihe bridge. This view seemed lo be subslanliated by ihe 

 marks found on the girders, the smashing of ihe second-class carriage, and 

 ihe dislance separaling ihis carriage from ihe fronl portion of ihe train. 



In Oclober 1873 ihere appeared in ihe British Quarterly Review 

 a irenchanl crilicism of Herbert Spencer's First Principles (Second Edilion). 



1 W. A. Tail, of Leslie and Reid, Engineers to the Edinburgh and District Water Trust. 



