== Apparent Inconsistancy == 

 This sentence: "He found that the water level at an average summer flood in the sea arm (when the water level reaches its maximum, not counting storms) was about the same as the level on the other side of the seadike, plus the margin of 9 feet and 5 inches." appears to read that at average summer flood, the water level in the Ij [the sea arm, also sea inlet below] was 9 ft 5 inches higher than in the Amsterdam canals. 

 This following sentence: "The waterlevel in the canals of Amsterdam—which is quite constant—called Amsterdam Peil (AP), equaled the level at summer flood at sea in the sea-inlet, which changes throughout the year."  seems to contradict that. 

 Is this a translation problem, or should this article be pulled?  It really says little about NAP.