APPLICATIONS OF TIMBER. 199 



to support, the new London Bridge is probably one 

 of the greatest, and certainly one of the most suc- 

 cessful instances of founding in coffer-dams. For 

 this work, the dams were made in the form of 

 ellipses, consisting of three rows of piles, dressed in 

 the joints, but without grooving, which is found not 

 to answer very well, more especially with such a 

 depth, and in so rapid a current. Some of those 

 piles were of the immense length of eighty or ninety 

 feet; and yet they were driven and puddled with 

 clay between the rows so accurately, that, all things 

 considered, the leakage was very trifling. 



SHITS. 



Ships of large dimensions have been constructed 

 in all ages. Some of the war gallies of the ancients 

 are represented as being hardly inferior in dimen- 

 sions to first rate line of battle ships of the present 

 day. The largest masses of timber that ever navi- 

 gated the ocean were, however, those constructed by 

 Mr. Wood of Port Glasgow, in the Isle of Orleans, 

 in the gulph of St. Lawrence. The first of these, 

 the Columbus, was three hundred feet long on the 

 deck, fifty feet seven inches broad amidships, and 

 twenty-nine feet and a half deep in the hold. She 

 was flat bottomed, and wall-sided, or had the sides 

 nearly perpendicular, and the stern post with little or 

 no inclination. The admeasured register of the Co- 

 lumbus was [about three thousand six hundred and 

 ninety tons; and her actual tonnage not much less 

 than five thousand. She had four masts, the largest 

 of which, however, was hardly equal to that of a 

 seventy-four. She came to England with a cargo of 

 timber in 1825, and arrived safely in the Thames; 

 but went to pieces on her voyage outwards, owing, 

 as is generally alleged, to the pilot committing some 

 error, or not being accustomed to conduct a mass so 



