Ash distribution and occurrence of ash fall in Scandinavia (Norway and Sweden) after the 1875 (29th and 30th March) eruption of the <a href="https://en.wikipedia.org/wiki/Askja" class="extiw" title="en:Askja">Askja volcano</a> (labelled “Krater” on the map) in eastern Iceland.
Henrik Mohn (15 May 1835 – 12 September 1916), astronomer and meteorologist, manager of the astronomical observatory of the Royal Frederick University (Kongelige Frederiks Universitet) of Christiania (Oslo), and director of the Norwegian Meteorological Institute (Norske Meteorologiske Institut)
1877
<i>Askeregnen den 29de – 30te Marts 1875.</i> Forhandlinger i Videnskabs-Selskabet i Christiania. Aar 1877, No. 10 (<a rel="nofollow" class="external text" href="https://www.biodiversitylibrary.org/page/43716286">BHL</a>)