Editing 1804 (section)

=== April–June ===
* [[April 2]] – Forty [[Armed merchantman|merchantmen]] are wrecked when a convoy led by British frigate {{HMS|Apollo|1799|6}} runs aground off Portugal with considerable loss of life.
* [[April 4]] – [[Samuel Taylor Coleridge]] sets sail on ''The Speedwell'' for the Mediterranean. In [[Malta]], he obtains employment as a public official.<ref>{{cite book|first1=Barry|last1=Hough|first2=Howard|last2=Davis|first3=Lydia|last3=Davis|title=Coleridge's Laws: A Study of Coleridge in Malta|url=https://books.google.com/books?id=hnR7GXkZz3oC&pg=PA28|year=2010|publisher=Open Book Publishers|isbn=978-1-906924-12-6|pages=28–}}</ref>
* [[April 5]] – The High Possil meteorite, the first recorded [[meteorite]] to fall in Scotland in modern times, falls at [[High Possil]].
* [[April 26]] – [[Henry Addington]] resigns as [[Prime Minister of the United Kingdom]].
* [[May 10]] – [[William Pitt the Younger]] begins his second term as Prime Minister of the United Kingdom.
* [[May 14]] – The [[Lewis and Clark Expedition]] departs from [[Camp Dubois]] and begins its historic journey by traveling up the [[Missouri River]].
* [[May 18]] – [[Napoleon]] Bonaparte is proclaimed [[Emperor of the French]] by the [[French Senate]].
* [[May 21]] – [[Père Lachaise Cemetery]] a {{convert|118|acre|km2|adj=on}} cemetery in Paris, France, is opened.
* [[June 9]] – [[Symphony No. 3 (Beethoven)|Beethoven's ''Symphony No. 3 in E–flat'']] is premiered in Vienna.
* [[June 15]] – The [[Twelfth Amendment to the United States Constitution]] is ratified by [[New Hampshire]], and arguably becomes effective (subsequently vetoed by the [[Governor of New Hampshire]]).
* [[June 21]] – [[Smithson Tennant]] announces the discovery of the elements [[iridium]] and [[osmium]]; three days later, [[William Hyde Wollaston]] reveals to the Royal Society that he is the formerly anonymous discoverer of [[palladium]].<ref>{{cite journal|title=The Eighth Group of the Periodic System and Some of its Problems|first=James Lewis|last=Howe|journal=The Chemical News and Journal of Physical Science|date=1900-07-20|page=31}}</ref>