EEPORT OF CAPT. GEORGE B. M«CLELLAN. 37 



Europe, after careful trial, would appear to be sufficient evidence that its theoretical advantages 

 are fully obtained in practice. On the march from Matamoras to Victoria and Tampico, in 

 1846 and 1847, 'we had infinite difficulty in bridging boggy streams (there being no suitable 

 timber) and in crossing ravines with vertical banks ; a few bays of the Birago trestles would 

 have saved us many days and a vast amount of labor. In the operations in the valley of 

 Mexico, our movements, checked as they so often were by impassable wet ditches and sometimes 

 by dry ravines, would have been rendered so much more free and rapid by the use of the Birago 

 trestles that our successes could have been gained at far less cost, and probably with even more 

 rapidity than they were. 



With respect to the boats : fully appreciating the great advantages arising from the lightness 

 of our India rubber pontons, I have never felt satisfied tliat they could afford, in practice, the 

 advantages expected of them. The material deteriorates and becomes worthless very rapidly, 

 probably the inevitable result of the process of manufacture. It is at least doubtful whether, 

 even in new pontons, the manner of attaching the cable affords sufficient strength, should a 

 heavy load cross the bridge, when thrown over a wide and rapid stream. The pontons are not 

 fit to be used as boats in ferrying troops over rapid streams, especially under fire. 



In attaching the frame to the ponton the loops soon give way, and cannot be repaired in the 

 field. 



The bridge has never been fairly tested ; that is, it has never been thrown across any stream, 

 much less a rapid one, and a heavy load passed over it. 



I would therefore suggest that the equipage ought not to be exclusively relied upon in the 

 field until it has been tested by taking it to some place where it can be thrown over a rapid 

 stream, at least 100 yards wide, and the heaviest loads passed over, and where, too, its capacity, 

 in the form of single boats and rafts, can be fully tried. I would at the same time suggest the 

 propriety of experimenting with sectional boats, after the manner of the Birago boats, but made 

 of the corrugated iron. 



Our force of artillery is large in proportion to the other arms of service, while the number of 

 our engineer troops is ridiculously and shamefully small ; it is, therefore, more than probable 

 that in any future siege it will be easy for the artillery to construct their own batteries, while 

 the engineers will be sufficiently burdened by the construction of the other works of attack ; we 

 have now, at last, the germ of an artillery school of practice ; I would then suggest, for the 

 consideration of the Secretary, the propriety of causing the artillery to construct their own 

 batteries. The position and armament of siege batteries should be determined by consultation 

 between the engineers and artillery, the former having the preponderating voice, in order to 

 secure the necessary harmony and connexion between all parts of the works of attack. 



I would recommend that the result of the ten years' experience of the engineer company be 

 reduced to form, and that a full and detailed system for the construction of material, saps, mines, 

 field works, bridges, construction of field ovens, repairs of roads, &c., be adopted and published 

 for the benefit of the service. 



If the artillery be charged with the construction of batteries, there should also be adopted and 



published for their use an artillery manual, comprising everything in relation to the preparation 



of the fascines, gabions, platforms, and magazines, the dimensions of batteries, manner of 



arranging working parties, &c. 



GEO. B. McCLELLAN, 



Captain 1st Cavalry. 

 January 14, 1857. 



