586 CUTTING OF MAKIlSrE ISTHMUSES. 



might produce very perceptible effects on tlie hydi-ograpliy of 

 the Cattegat. 



When we consider the number of narrow necks or isthmuses 

 which separate gulfs and bays of the sea from each other or 

 from the main ocean, and take into account the time and cost 

 and risks of navigation which would be saved by executing 

 channels to connect such waters, thus avoiding the necessity 

 of doubhng long capes and promontories, and even continents, 

 it seems strange that more of the enterprise and money, which 

 have been so lavishly expended in forming artificial rivers for 

 internal navigation, should not have been bestowed upon the con- 

 struction of maritime canals. Many such have been projected 

 in early and in recent ages, and some trifling cuts between marine 

 waters had been actually made ; but before the construction of 

 the Suez Canal, no work of this sort, possessing real geographical 

 or even commercial importance, had been effected. 



These enterprises are attended with difficulties and open to 

 objections which are not, at first sight, obvious, Nature guards 

 well the chains by which she connects promontories with main- 

 lands, and binds continents together. Isthmuses are usually com- 

 posed of adamantine rock or of shifting sands — the latter being 

 much the more refractory material to deal with. In all such 

 works there is a necessity for deep excavation below low-water 

 mark — always a matter of great difficulty ; the dimensions of 

 channels for sea-going ships must be much greater than those of 

 canals of inland navigation ; the height of the masts or smoke- 

 pipes of that class of vessels would often render bridging im- 

 possible, and thus a ship-canal might obstnict a communication 

 more important than that which it was intended to promote ; the 

 securing of the entrances of marine canals and the construction 

 of ports at their termini would in general be difficult and expen- 

 sive, and the harbors and the channel which connected them 

 would be extremely liable to fill up by deposits washed in from 

 sea and shore. Besides all this there is, in many cases, an alarm- 

 ing uncertainty as to the effects of joining together waters 

 which nature has put asunder. A new channel may deflect 

 strong currents from safe courses, and thus occasion destructive 

 erosion of shores otherwise secure, or promote the transportation 

 of sand or slime to block up important harbors, or it may furnish 



