146 The comparative cheapness of Large and Small arched Bridges. [Jan. 



merge the one into the other, so as to render it difficult to decide at 

 what point the surf first breaks. The particulars with regard to the 

 tides (ah-eadv given at the beginningof the last page) differ in some res- 

 pects from those found some years ago by Col. De Havilland : it is pro- 

 bable, however, that his observations were not made during the north- 

 east monsoon, to which the results here given particularly belong. 



Madras, l^th December, 1838, 



N. B.— The above elevations of the Station above the level of the sea with the 5 feet 

 telescope, have for the sake of comparison been reduced to the same elevation as 

 those of the theodolite— Ave have— ^- ^* 



Elevation of theodolite station above mean level of the sea 32 4 



above the floor of the veraadah 5 1 



Floor of verandah above mean level of sea , 27 3 



VII. — The comparative cheapness of Large and Small arched Bridges, 

 To the Editor of the Madras Journal of Literature and Science. 



Dear Sir, — It is some time since heard that Government was go- 

 ing to construct a work of vast public utility near Trichinopoly, namely 

 a permanent bridge across the river Cauvery, and it is now rumoured 

 that the Court of Directors have liberally sanctioned this beneficial un- 

 dertaking ; and determined, as the most economical mode of constructi- 

 on, that it shall consist of 40 small arches. 



Now as I feel rather sceptical whether this notion of economy is cor- 

 rect, and it w^ould be a pity to see a work of this kind constructed with- 

 out regard to appearance, if nothing is gained by the neglect, I have de- 

 termined to submit the question of the comparative cheapness of large 

 and small arched bridges, to the learned among your readers ; in hopes, 

 if I am wrong, of having my doubts removed ; or, if I am right, of confer- 

 iug a benefit on our Trichinopoly public by promoting the better orna- 

 menting of the town. 



There are two ways in Avhich people commonly talk of bridges ; either 

 as an artificial platform, from one side of a river to the other, which is 

 cheap in proportion as it is thin ; or as a road-way, supported by piers, 



