( 856 ) 



neglecting llie usually small tidal oscillation in the Atlantic and 

 further starting from the following suppositions: 



1. that experience shows that on a canal communicating on the 

 one side with a sea of variable level, on the other side with a sea 

 of constant level, the amplitude of the tidal curve diminishes uni- 

 formly from one sea to the other and further that the retardation 

 of the tide is proportional to the distance, that therefore : 



if Y= half the amplitude of the tides of the Pacific, 

 1= length of the canal, 

 to = velocity of propagation of the tides, 



the level y, with respect to the mean canal- or sea-level, at a 

 distance % from the Pacific, will he: 



y = - r { 1 -T) m ( 2t -ii 



2. that, in accordance with what has heen observed on similar 

 canals, particularly on the Suez-canal between Suez and the Bitter- 

 Lakes, the velocity of propagation of the tide can be represented by 

 the well known formula : 



I/ ■ ( /z + 4 y ) * Kv 



where 



£T= depth of the canal below mean sea-level, 

 v = velocity of the current, 

 K= constant (0.4 at flood-time, 1.2 at ebb); 



3. that, from the levels which have been derived by means of the 

 suppositions 1. and 2. for any moment and for two mutually not 

 too distant places, the velocity of the current for that moment may 

 be computed by applying the formula : 



v = 56,86 [/Ri — 0.07. 



By means of these suppositions the velocity of the currents have 

 been computed for places at 9, 27, 45 and 63 K.M. from the Pacific, 

 assuming a tide of the amplitude of 6.76 M. The results are as 

 follows l ) : 



'*) The length of the canal which according to the project made at that time, 

 would amount to 72 K.M. has been put at 76 K.M. in the calculations to allow 

 for the curves. The bottomwidth was put at 21 M, the depth at 11.50 M. below 

 mean sea-level at Panama, and 9 M. at Colon, the slopes at 1 horizontal on 

 1 vertical. 



