Intelligence and Miscellaneous Articles. 75 



does not appear to have been any proper drawing prepared, nor the 

 necessary practical instructions given for the certain construction of 

 the oblique bridges, which have been built upon a very extensive pub- 

 lic work since 1832 ; but that the contractors were suffered to exer- 

 cise their own judgement in the erection of them ; and in one case 

 (decidedly the most important one of the whole,) the entire manage- 

 ment was, it appears^ left to one of the operative masons in the em- 

 ploy of the contractor for the building of the bridge. I have been 

 particular in relating these circumstances, in order to show how little 

 attention has been ))aid to the proper construction of oblique bridges 

 hitherto, ivliich require the greatest care, notwithstanding your valuable 

 work on the subject, as well also to suggest the probability that Mr. 

 Fox was aware of the want of a general and proper rule in the cases 

 alluded to, and hence his mistaken notion that " formerly,** that is, 

 previously to his lecture a few months ago, ** the stones were cut by 

 no general rule, but merely fitted to their particular place." 



I sincerely hope that the inquiry which has be^n set on foot, with 

 a view to prove that a sure rule for the spiral formation of the stones 

 has existed for several years, will lead to some advantage, and I am 

 informed that already, that is, since the commencement of the in- 

 quiry, the executive engineer of a very extensive public railroad has 

 very prudently applied to a competent person for a defnite develop, 

 ment of your principle^ so that m future he may possess a safe guide ; 

 thus verifying the adage, ** better late than never." 



It is too clear that at the present time there is a sort of mania for 

 oblique bridges. That in many cases, though not so frequently as 

 they occur, they are indispensable upon railroad lines, but for 

 turnpike roads, where the rate of travelling rarely reaches 1 I miles 

 an hour, and considering the absence of lateral friction, now that our 

 roads are no longer ** gridironed," and the little risk, comparatively; 

 of departing from the proper course, so great an inconvenience in 

 railroads, though strikingly disregarded in various situations^ I am 

 firmly of opinion, after an attentive observation of the practical work- 

 ing of the best rule, that it is very injudicious to adopt them, except 

 in cases of absolute necessity. The fact too, that your opinion fully 

 coincides with the one represented in the Encyclopedia Britannica, 

 article " Stone Masonry," viz. *Hhat oblique bridges should be avoided 

 whenever it is possible" is, I submit, a very strong proof of their in- 

 feriority. I am. Sir, very respectfully. 



Your obedient servant, 



Hknry Welch, 

 Surveyor of the County Bridges of Northumberland. 

 Elswick Villa, Newcastle, Nov. 17, 1 836. 



Mr. Fox's paper alluded to above appeared in Lond. and Edinb. 

 Phil. Mag., vol. viii. p. 299. 



OBSERVATIONS ON THE AURORA BOREALIS. 



1. Aurora visible at Dublin on Thursday, 29th September, 1836. 



The 29th of September last was a cloudy and showery day, but the 



L2 



