HAlLRO.AnS. 507 



annual cost of a single engine, kept at constant work, is not lesss than 

 £1500; and, on a frequented road, the rails will probably require 

 renewing every six or seven years. To meet all contingent expenses 

 of this nature a reserved fund must be maintained. 



In the above cautionary statements, we have taken some pains to 

 obtain accuracy, and we think that they may be safely adopted as a 

 general guide. Some knowledge of the elements entering into rail- 

 road estimates, by an unprejudiced writer, is very necessary at a 

 time when adventurous engineers and intriguants m the money mar- 

 ket are unhesitatingly putting forth statements that cannot be real- 

 ized, and on these statements grounding claims to the support of ca- 

 pitalists for schemes that can only end in waste of labour, and the 

 ruin of the shareholders. " Wood on Railroads,'' M'Neill's transla- 

 tion of M. Navier's excellent pamphlet on the Method of estimating 

 lines of Railroad, and the chapters on Locomotives in Dr. Lardner's 

 " Steam Engine," may be consulted with great advantage by all per- 

 sons desiring substantial knowledge on this important subject. 



We mean to conclude the present article with a description of the 

 London and Birmingham railway, which, as furnishing a central line 

 of communication not only between London and Birmingham, but 

 with all the important manufacturing towns of Lancashire, West- 

 Yorkshire, Derby, and Staffordshire, we consider as the great artery, 

 — the railroad aorta, if the term is allowable, of our population-cir- 

 culating system : and with respect to it, as well as to three or 

 Jour others, we doubt not that the most successful results may be 

 expected. 



The length of the London and Birmingham railway (of which we 

 offer to our readers a reduced and modified lithographed section) is 

 rather more than 1 1 1 miles.* Commencing at a height of about nine 

 feet above the level of the Regent's canal (108 ft. 9 in.), it first 

 passes the tunnel of Primrose Hill (five furlongs), and crossing the 

 Brent River at an elevation of 87i feet, it passes on to the Colne, 

 at Watford, rising in the first sixteen miles only 120 feet., i. e. eio-ht 

 feet per mile. About two miles beyond Watford (189 feet), the plastic 

 clay stratum is tunnelled for about a mile in length ; and from thence 

 by Berkhampstead to the summit of the chalk-ridge to a point nearly 

 half-way between Tring and Albury there is a rise of about iO^ feet 

 per mile. After crossing the chalk hills, the railroad enters the up- 

 per part of the vale of Aylesbury, and near Leighton Buzzard enters 

 the Ouse drainage, crossing the upper part of the Ouse west of 

 Buckingham, on a viaduct about fifty feet above the river, whose level 

 at that point is 214 feet above the sea. From Stony Sti-atford to 

 Blisworth (the situation of the great tunnel of the Grand Junction 

 Canal) there is a rise of twelve feet per mile. The elevation of the 

 oolite ridge near Kilsby, where the railroad is tunnelled through for 

 one mile and three furlongs, 123 feet below the hill top, is 516^ feet 

 above the sea ; and this is the summit level of the railroad. Crick 

 tunnel on the Grand Union Canal, within two miles of the summit, 

 is 424^ feet high ; and Braunston tunnel, which forms part of the 

 uniting line of canal between the Grand Junction and Oxford canals, 



• This section may be had of the PnblisliPis, price 6rf. 



