386 Intelligence and Miscellaneous Articles. 



Causes of the Accident. As we conceive the public have a right 

 to be fully informed with respect to the.causes of an accident of this 

 alarming nature, we have made some particular inquiries on the 

 subject, the results of which we shall lay before our readers j not 

 only that they may form an opinion upon this particular case, but 

 also that they may be enabled to judge how far it is calculated 

 to render doubtful the security of structures of this kind, a con- 

 siderable number of which have now been erected in different parts 

 of the kingdom. 



Immediately after the accident, it was discovered to have arisen 

 from the breaking of one of the chains, by which the iron pillars 

 supporting the bridge are stayed and supported ; and which chains, 

 as our readers are no doubt aware, are carried to some distance 

 on each side of the river, and secured to a great mass of masonry 

 sunk into the ground. By the breaking of this chain, the pillar 

 was of course deprived of its support, and the weight of the bridge 

 immediately drew it from its situation, as we have already de- 

 scribed. It remains then to ascertain the causes of the failure of 

 the chain. There is no doubt that the immediate cause was the 

 powerful vibration communicated to the bridge by the measured 

 and uniform step of the soldiers. If the same, or a much larger 

 number of persons had passed over in a crowd, and without ob- 

 serving any regular step, in all probability the accident would not 

 have happened, because the tread of one person would have 

 counteracted the vibration arising from that of another. But the 

 soldiers all stepping at the same time, and at regular intervals, 

 communicated, as we mentioned in describing the accident, a 

 powerful vibration to the bridge, which went on increasing with 

 every successive step j and which, causing the weight of the bridge 

 to act with successive jerks on the stay-chains, had a more powerful 

 effect upon them than a dead weight of much larger amount would 

 have had, and at length broke one of the cross bolts by which the 

 links of the chain are joined together. Perhaps this accident, 

 alarming and injurious as it has been, may have the effect of pre- 

 venting some more dreadful catastrophe in other quarters. From 

 what has happened on this occasion, we should greatly doubt the 

 stability of the great Menai bridge (admirable as its construction is), 

 if a thousand men were to be marched across it in close column, and 

 keeping regular step. From its great length, the vibrations would 

 be tremendous before the head of the column had reached the 

 further side, and some terrific calamity would be very likely to 

 happen. If any considerable number of troops should be marched 

 across that bridge (which, from its being one of the principal routes 

 to Ireland, is not improbable), we hope the commanding officer 

 will take the precaution of dismissing his men from their ranks be- 

 fore they attempt to cross : indeed, that precaution should be ob- 

 served by troops crossing all chain bridges, however small they 

 may be*." But 



* The following remarks on this part of the subject are given in the 

 Manchester Chronicle': " It has been stated by some scientific men, and 

 we fully concur in the opinion, that the peculiar manner in which the 



soldiers 



