74 Pape>$ connected with the construction No. 31 ] 



remains of improving the communication between the shore and the ship- 

 ping, is the erection of a pier. 



The question being thus laid down, it is necessary to examine what are 

 the requisites of the pier in order to conclude from that examination, which 

 of the different structures of this description answers them best, and con- 

 sequently ought to be preferred; these requisites are: 



1st. That the kind of structure adopted should change nothing in the 

 region of the sea, along the coast, and for that, it must oppose no (or, 

 but very little) resistance to its action. 



2d. That the stability should be as great as the durability, which can- 

 not be obtained, but if the materials employed for the structure, have the 

 required qualities for these requisites being equally ensured. 



The cause to which the coast of Corromandel owes its formation, continu- 

 ing in action, though much less rapid than it was in former times, new 

 strata of sand are added to ancient ones, and form successive deposits 

 which are not very sensible when they are equally distributed upon a 

 great length of coast, but which would soon appear, if the sands were 

 stopped in their progress by any obstacle ; this is what would take place 

 if the structure adopted was a full one such as a stone pier, the sands 

 accumulating on one side or other, according to the currents being north 

 or south, would by dint of time, reach its farther extremity, and, from this 

 moment, it would no longer be of any use ; this kind of structure, which 

 is besides very expensive, not being fit for the place, there is but an open 

 work which can be erected, without any such inconveniency. The open 

 works are timber piers, for tne construction of which nothing but timber 

 is employed ; the suspension piers, for which the piles for the pillars and 

 the planking only are of timber, the remaining being of wrought iron and 

 cast iron, and at last, the fixed pier similar to the one projected, which 

 are wholly of wrought iron and cast iron, the planking excepted. To 

 pronounce with exactitude, upon the merits of these different systems, we 

 must examine the advantages'and inconveniences presented by each of 

 them. The timber piers have, upon the suspension pier, the advantage 

 of a greater stability, but they are not so easily repaired and do not last so 

 long, all their parts being equally liable to a rapid decay, while in the 

 suspension piers, the piles which form the pillars and the planking only 

 are exposed to the same causes of destruction. The sea worms are so 

 abundant in the Indian ocean, that at Bourbon, a timber pier was entire- 

 ly destroyed; in less than one year after its erection. Xt is true that a pro- 



