( 865 ) 



to 45 M. width and 10.5 M. depth is being executed, After tins 

 widening, navigation will certainly experience still less difficulty 

 than at present, Meanwhile, and this point deserves attention, the 

 velocity of the current after the completion of the widening for the 

 w r hole of the canal between Suez and the Bitter Lakes, will not be 

 lessened but increased. For, owing to the surface of the two Bitter 

 Lakes, which is about 23800 H.A., the widening will only cause 

 insignificant modifications in the level of these Lakes. Consequently 

 the fall of the water between the Red Sea and the Bitter Lakes 

 will be nearly unaltered after the widening both at high — and low 

 water. Under these circumstances the enlargement of the cross 

 section will necessarily cause increased velocity of the current. 



The mere consideration of the maximum velocity which may 

 occur during a few hours every year, and even then only on the 

 side of the Pacific, is evidently inadequate for reaching a true 

 estimate about the question whether the velocities of the current in an 

 open Panama-canal without lock will offer difficulties of any impor- 

 tance for navigation. We have to pay regard in the first place to 

 the velocities which will regularly occur on the whole length of the 

 canal at mean spring-tide and mean neaptide. 



These velocities may be derived with some approximation from 

 those found by the French Academy for a maximum difference in 

 tide of 6.76 M. 1 ), at least if we suppose that these velocities will 

 not considerably deviate from the truth. 



We thus find for the maximum velocities 



at K.M. 9 27 45 63 



at mean neap tide : 0.70 M. 0.67 M. 0.59 M. 0.51 M. 



„ „ spring „ 1.01 „ 0.96 „ 0.85 „ 0.74 „ 



The following diagrams show the velocities of the current, for the 

 interval of from 9 to 63 K.M. distance to the Pacific, at mean spring 

 tide and mean neap tide, to 6 Moon-hours after ebb on the Pacific. 

 They were derived from the calculations of the French Academy 

 of Sciences. 



l ) The approximation neglects the differences of the velocities of propagation of 

 the tide for different amplitudes We thus obtain for the velocity v', at an arbitrary 

 place, the amplitude being y', the following value, which is expressed in terms 

 of the velocity v for an amplitude y : 



{v' -f 0.07) = (v -f 0.07) ' 



V 



59* 



