1832.] A Method of rectifying a Route Protraction. 19 



are solid to the height of the top of the cut-waters, after which they are 

 completed with longitudinal stone walls, covered over with large stones, 

 just under the road-way. The arch stones are five feet long at the spring, 

 and diminish gradually to the key stones, which are 2 ft. 9 in. In the arch 

 under the approach, they are six feet at the spring, and 3 2 at the crown. 



During the progress of the work, it was invariably observed, that 

 before the keys were driven, the centres had sunk 3^ inches at the 

 crown ; and when they were struck, which was done the second or third 

 day after the arch was finished, that there was a settling of 2^ inches. 

 The large arch settled 3£ inches, and several of the long stones at the 

 haunches cracked, which however can hardly be considered detriment- 

 al, as it is only a proof that the hollows, which would otherwise have 

 existed, have by the fractures been filled up." 



We are greatly surprized to find, from the statement furnished to 

 the resident by Captain Oliphant, that the outlay upon this extensive 

 structure exhibits a total of less than 95,000 rupees, or including the 

 labour of 90 men from the Corps of Engineers, rupees 1,02,000, not 

 including the repair of the damage sustained in the flood of the 22nd 

 October, 1829. Considering the dimensions of the bridge, and the 

 high price of labor in the Nizam's dominions, this seems exceedingly 

 moderate : it must however be remembered, that the foundations rest 

 upon rock, and that the granite quarries, whence the stone was extract- 

 ed, are close at hand. 



We have given a reduced engraving of the architectural elevation 

 and plan of the bridge, in Plate II. figs. 1, 2, 3, 4, which do not re- 

 quire any explanation : the plan adopted of springing the voussoirs of 

 the elliptical arches from an inclined bed on the piers, so as to rest at 

 right angles to the thrust of the arch, instead of forming right angles 

 with the curvature of the ellipse, reminds us of Mr. Seaward's elegant 

 design for the new London bridge, wherein the advantage of such a 

 construction is fully developed. The attempting of elliptical arches in 

 6tone, with native mistris, was a work of daring, and its successful 

 accomplishment does credit to the perseverance and abilities of 

 Captain Oliphant. 



VI. — A Method of rectifying a Route Protraction. 



It frequently happens, that a surveyor has to protract a survey of his 

 route between two fixed points on a map, and that when the operation 

 is performed, he finds the work does not close, and perhaps the termi- 

 nating point of his protraction either goes beyond or falls short of the 



d 2 



