( 860 ) 



Suppose these corrections for the consecutive half hours to be 

 for K.M. 9 = «f lf ef a , <f„ <f 4 , 

 for K.M. 27 = <f x \ rf 2 ', ef 8 \ <f 4 ', 

 we find for the values of the corrections : 



6 X = + 0.15 J/. d/ = — 0,13 .1/. 



ef,= + 0.12 „ cf s '=- 0,10 „ 



d, = - 0.04 „ d t ' = + 0,04 „ 



if 4 = - 0,01 „ rf 4 ' = + 0,01 „ 



Therefore, applying the corrections, for the velocities themselves: 



at K.M. 9 at K.M. 27 



at 4\/ 2 hours 1,17 M. 0,80 M. 



„ 5 „ 1,29 „ 0,96 „ 



„ 57, „ 1,12 „ 1,15 ,. 



,, 6 „ 1,08 „ 1,07 „ 



From these numbers it appears that we can satisfy the condition 

 of continuity at least for the part 9 — 27, during the period between 

 4 1 2 and 6 hours after low tide, by relatively speaking slight modi- 

 fications of the computed velocities. 



It cannot be denied, however, that the circumstance of the condition 

 of continuity not being necessarily satisfied in applying this method 

 of computing the velocities, indicates that this method is uncertain 

 to some extent ; though it appears that the uncertainty, at least as 

 regards the calculation of the maximum velocities, will be small. 



Another reason of uncertainty in the computation of the velocities 

 lies in the value assumed for the coefficient of the formula for 

 uniform motion. 



This vialue, 56,86, is not the result of a great number of obser- 

 vations made on rivers and canals of about the same inclination 

 and depth as the Panama-canal, but of observations for rivers of 

 considerably smaller depth. 



We may of course test the validity of this coefficient, as well as, 

 more generally, the validity of the formula itself, by comparing the 

 velocities it yields for the Suez-canal with those really observed there. 

 Of the observations which have been made about the velocities in 

 that part of the canal which lies between the Bitler Lakes and 

 Port-Thewiik, those of 23 July, and 8 en 22 August and 6 September 

 1892 have been published x ). 



These observations, however, are insufficient for a fair comparison. 



!) See : The Suez-canal according to the posthumous papers of I. F. W. Conrad 

 arranged by R. A. van Sandick. Tijdschrift Kon. Instituut van Ingenieurs 1902— 1903, 

 p. 89 and 90. 



