View source for Normalnull

{{Short description|Outdated official vertical datum used in Germany}}
{{DISPLAYTITLE:{{lang|de|Normalnull|nocat=y}}}}
[[File:Borne de nivellement Kriegstor.JPG|thumb|Sign referring to {{lang|de|Normal-Null}}]]
'''{{lang|de|Normalnull}}''' ("standard zero") or '''{{lang|de|Normal-Null}}''' (short '''N.&nbsp;N.''' or '''NN''') is an outdated official [[vertical datum]] used in Germany. Elevations using this reference system were to be marked {{lang|de|Meter über Normal-Null}} (“meters above standard zero”). {{lang|de|Normalnull}} has been replaced by {{lang|de|[[Normalhöhennull]]}} (NHN).

== History ==
In 1878 reference heights were taken from the [[Amsterdam Ordnance Datum]] and transferred to the [[Berlin Observatory#New Berlin Observatory|New Berlin Observatory]] in order to define the [[Normalhöhenpunkt 1879|{{lang|de|Normalhöhenpunkt|cat=no}} 1879]]. {{lang|de|Normalnull}} has been defined as a level going through an imaginary point 37.000&nbsp;m below {{lang|de|Normalhöhenpunkt 1879}}. When the New Berlin Observatory was demolished in 1912 the reference point was moved east to the village of [[Hoppegarten|{{langr|de|Hoppegarten|cat=no}}]] (now part of the town of [[Müncheberg|{{lang|de|Müncheberg|cat=no}}]], Brandenburg, Germany).<ref>{{langr|de|S. German}}: {{lang|de|Was ist "Normal-Null"?}}. In: ''{{lang|de|Physikalische Blätter}}'' 1958, vol 14, issue 2, p. 62–66 {{ISSN|1521-3722}} {{doi|10.1002/phbl.19580140203}}</ref>

== References ==
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[[Category:Vertical datums]]
[[Category:Geography of Germany]]