Nice find, Santino!
The origin of these letters:
Approximately 40,000 Dutch letters from the second half of the 17th to the early 19th centuries have been gathering dust for centuries in British archives. They were sent home by sailors and others from abroad but also vice versa by those staying behind who needed to keep in touch with their loved ones. Many letters did not reach their destinations: they were taken as loot by privateers and confiscated by the High Court of Admiralty during the wars fought between The Netherlands and England.