504 RAILROADS. 



we beg the attention of our readers, to whom, as to merely generally 

 informed persons, we address these observations. 



On the subject of tunnels, forming the Isist division of our general 

 remarks, we think that the inconveniences of such excavations are 

 not considered as they ought to be. The writer of the present article 

 knows something of the unpleasantness felt in passing canal-tunnels 

 in the manufacturing districts ; and his own experience, besides being 

 confirmed by the opinions of practical men, is warranted, as it were, 

 by the nice experiments made by Dr. Lardner. On these grounds, 

 we cannot honestly withhold the expression of our conviction, that 

 long tunnels on railroads are quite incompatible with the conveyance 

 of passengers on a large scale. 



On the Leeds and Manchester railroad, for instance, little opposi- 

 tion should be offered to such a project, where goods, so far as we are 

 able to judge, will form the chief subject of transport; but with re- 

 spect to the Birmingham railway, which, from its central situation, 

 seems to be the grand trunk for all railways connecting the metro- 

 polls with the northern manufacturing districts, we cannot but lament 

 that a tunnel of such length should have been projected, where we 

 are certain that all the extra expenses of deep-cutting would in a 

 short time be more than counterbalanced by the increased demand 

 of passengers. The tunnel to which reference is now made crosses 

 the lower oolite and lias ridge, and measures, on the section from 

 which these calculations are made, one mile and three furlongs. The 

 chief inconveniences of tunnels arise from two causes: from the ge- 

 neration of noxious air from the walls surrounding the tunnel, and 

 the absence of a free access for the oxygen ; secondly, from the con- 

 sumption of the oxygen within the tunnel necessary for combustion in 

 the engine-furnaces. As additional drawbacks, that must always 

 have a practical influence, we mention the transition from light to 

 darkness, and the sensation of cold and dampness, that must be expe- 

 rienced by every one passing at the most rapid rate through a tunnel 

 of more than a mile in length, and proportionably more as ventilating 

 shafts are neglected. These should be placed at distances not more 

 than a hundred and fifty yards apart. Even under the most favour- 

 able circumstances that can attend a long tunnel, the rarefaction of 

 air pi-oduced by the heat, and the foul air from the engine, will, 

 under any tunnel, however spacious, cause an unpleasant sensation to 

 the passengers ; and, when trains are passing through, little or no 

 benefit will be felt from shaft ventilation ; so that under all circum- 

 stances much attention should be paid to make tunnels on great and 

 population-transporting railroads as few and as short as possible. 



We have thus, as succinctly as we could, laid down those princi- 

 ples that we think most worthy of attention ; and if we shall have 

 succeeded in thoroughly convincing a single person who has ad- 

 vanced, or is about to advance, his capital in support of these under- 

 takings, we shall not have written in vain. We have not written 

 under a feeling of alarm, or with a view of alarming others ; for we 

 have no fears as to the advantages, great, glorious, and far beyond 

 what can be calculated by our short-sighted arithmetic, that shall re- 

 sult from the establishment of a rapid communication (or what is in 



