( 854 ) 



equal to the mean level and besides, that tins most rapid change is 

 equal to double the mean change, the maximum inflow is put at 

 2 x 321 = 642 M 8 . 



As the wet section of the canal at the mean level is about 277 M s , 



642 



we tind - = 2.32 M. per second for the maximum velocity. 



272 



It is easily seen that these calculations are valueless. For the fact 

 has been wholly overlooked that a certain time must elapse before 

 some rise or fall at the mouth of the canal on the Pacific will make 

 itself felt over the whole length of the canal. If therefore, shortly 

 after ebb, the level in the canal near its mouth begins to rise and, 

 shortly afterwards, the first inflow takes place, the level of the canal 

 further inland will still be falling and the water will there be 

 Mowing out as a consequence. Similarly when shortly after the moment 

 of high tide on the sea, the level of the canal near its mouth begins 

 to fall and shortly afterwards outflow sets in, the level further 

 inland will still be rising and there the inflow will not yet have ceased. 



Moreover the in- and outflow of the canal on the side of the 

 Atlantic has been left wholly out of consideration. They will certainly 

 not be small but will not take place at the same moments as the 

 in- and outflow on the side of the Pacific. We may see that the 

 difference in time, before mentioned, will not be insignificant but 

 will have a great importance, by considering that, on the Suez-canal, 

 the propagation of the high tide takes place with a velocity of about 

 10 M. p. second. Assuming the same velocity for the Panama-canal 

 the propagation of the tidal motion over the whole of the length 

 of the canal will require about 2 hours. As a consequence the 

 currents near the two terminals of the canal will have different 

 directions during a great part of the tide. 



The incorrectness of the reasons for the conclusion of the congress 

 of 1879, according to which a lock is to be considered an absolute 

 necessity seems to have attracted little attention at that time, and 

 consequently the canal was originally executed with the intention 

 of building a sluice on the side of the Pacific. 



Ferdinand de Lesseps, who always considered it a great advantage 

 that the Suez-canal was executed without locks, probably never 

 favoured this lock in the project of the Panama-canal. This led 

 him in May 1886 to address himself to the French Academy of 

 Sciences, requesting it to institute an investigation about the influence 

 of the tidal motion of the Pacific and the Atlantic on the motion 

 of the water in an open Panama-canal. 



The commission charged with this investigation reported on the 



