( 747 ) 



a great many wells lia\c heen sunk lor niililary piu-jtoses, niosl of 

 which well^ are about 50 M. t~ A.l*. deep. The le\(^ls in (licni were 

 repeatedly sounded by me, which, considering their large number, 

 led to important results. Sjiecially of great signiticancc^ is what those 

 soundings teach iis, as to the direction in which the deep underground 

 water moves. Subjoined table, in \vhich, as much as possible, only 

 wells of corresponding depths lia^e beeu put down, entirely confirms 

 what I found elsewhere. 



Those soundings were done on .lune 5^'' 1903. The distances of 

 the wells to the H.M. polder itself, one will get by adding 80 M. to 

 the tigure that expresses the distance between them and the encircling 

 canal. 



Here clearly comes out a motion of the deep underground water, 

 from the higher polders, north of the Haarlemmermeer polder, 

 towards this deep ])older. On 1200 M. of distance there is an 

 inclination of 0.22 M., or 1,8:10000, whereas in other directions, 

 there is no regular inclination. That indeed no general motion from 

 east to west or vice versa is to be thought of, naturally follows 

 from the comparison between the level of the water in ^vells thus 

 situated. For instance from the following row of wells, all at 25 M. 

 from the encircling canal of the H. M. polder. 



