Ji9(i IMajor-General Sir Howard Douglas on 



bridges, are detailed with great minuteness, which cannot fail to 

 be useful to all engineers engaged in similar pursuits. 



The third section treats of Bridges of Boats. The subject 

 is managed with great ability. The French engineers think 

 that the size of the boats should correspond with the magnitude 

 of the river. For the Danube, the length should be 60 feet; 

 for the Po, 50 feet ; for the Tanaro or Taro about 20 feet, 

 with a breadth of about 10 feet and a depth of 3 feet. Sir 

 H. Douglas is of opinion, that the two first are far too long. 

 In large tide rivers, subject to heavy swells, decked lighters 

 are very convenient ; and in some cases, as in the passage of 

 the Adour by the Duke of Wellington's army in 1814, they 

 were indispensably necessary. A curious, and we should think 

 useful, composition for covering the tarred canvass applied to 

 pontoons, may be seen at pages 105 and 106. 



After having shown the most approved methods of laying 

 down pontoon bridges, the manoeuvre of withdrawing a bridge 

 entire is also carefully described, and every operation correctly 

 explained. The converse operation of restoring a bridge after 

 it has been withdrawn, in both small and large rivers, is treated 

 at full length, so as to be easily understood by engineers em- 

 ployed in these services. Our author next illustrates his dif- 

 ferent maxims by detailing the passages of various rivers by dis- 

 tinguished military commanders. 



" The passage of the Douro, in May 1809, by Lieutenant-General Sir 

 Arthur Wellesley, may be cited as a splendid and very instructive example 

 of what may be effected by judicious combinations and arrangements, with 

 very trifling material means, in forcing the passage of a river not properly 

 watched and guarded ; and shows the importance of providing columns of 

 troops intended for such enterprises by a few row boats, with which to com- 

 mence instantly an attempt that might otherwise be defeated by the most 

 obvious and simple precautions on the part of an enemy, — a practical deduc- 

 tion may weU be enforced from the fact, that this very celebrated operation 

 was commenced with 6ne small boat, procured by an accidental circumstance. 

 The whole of this operation is beautifully described by Colonel Napier in his 

 account of the Peninsular War. 



" After the affair of Grijon on 11th of May, in which the French troqpg 

 were forced to abandon their position, and to retire, pressed by the Britis]ji 

 cavalry, first to Carvalho and then to Villa Nova, opposite to Oporto, they 

 crossed the Douro by the bridge of boats, arid,lri tile riight,1)roke lip that 

 communication. • 



" The reports made to Marshal Soult of the direction of General Hill's 



