( 852 ) 



velocity <>t' t.18 M. per second. 2.<>4 miles per hour. The Hoard 

 i- of opinion that such a velocity will be no hindrance to navigation. 

 These same velocities will occur in an open canal as well as in 

 a sea-level canal with tidal lock, at least it' in both cases the water 

 of the rivers must he carried off' by the canal. They occur very 

 rarely however and need not necessarily lead to an increase of 

 the maximum velocities caused by the tidal motion. 



§ 2. The reasons which led the technical commission of the 

 Congress of Paris in 1879 to expect currents with a velocity of 

 2 — 2,50 M. per second in an open canal, are twofold. In the first 

 place, tin' commission gave some examples of currents with a velo- 

 city of 2 — 3,50 M. per second observed on the lower course of 

 rivers where similar differences exist between high and low-water 

 as on the Panama canal on the Side of the Pacific. 1 ) 



In the second place the commission published a memorandum of 

 .Mr. Kleitz, one of its members, containing some summary calcula- 

 tions in regard to the velocities which must be expected in an open 

 canal. 2 ) 



It is evident that on the lower end of a river with a great 

 amplitude of the tide very considerable velocities of the current 

 may occur; but it does not follow that equal velocities will occur 

 in an open Panama-canal. This will be the ease only if the remaining 

 circumstances which have a decisive influence on the velocity are 

 about the same in the two cases. Now it is evident that the velocity 

 ut' the current caused by the tidal motion of the water will be no 

 less dependent on the depth and in particular on the mean depth 

 for the whole of the width, than on the amplitude of the tide and 

 ilii- irrespective of the question whether we have to do with a river or 

 with an open canal of relatively great length. In other words the 

 velocity of the current will depend as well on the proportion of 

 the amplitude to the mean depth as on each of these quantities 

 separately. Furthermore it is easily seen that in a river these velo- 

 cities will depend in a great measure not only on the discharge 

 but also on the changes of width and depth and on the inclination 

 of the bottom near its mouth. In fact, the examples communi- 

 cated by the commission show clearly that the velocity must be 

 dependent in a high measure on other causes besides the amplitude 

 of the tides. For among the examples of the commission we find 

 the Riviere dc l'Odet with an amplitude of the tides of 5 M. and 



1 ) See: Congres international d'études du canal interocéanique. Compte rendu 

 des séances. Paris 1879 page 3G2. 



2) lb. p. 384 and PI. IV fig. 6. 



