This five-volume assembly of letters and reports by the officer that eventually became Wellington's artillery commander is both an unusual and an extremely helpful addition to the usually sparse period literature on artillery. It was published by Ken Trotman some years ago, but it does not include the material on the New Orleans campaign of 1815, which is unfortunate. Dickson's participation in the campaign negated him taking up his old post with Wellington's army in Belgium, as he had not returned from North America in time. Wellington did give him the post of commander of the siege train. Dickson is the outstanding British senior artillery officer of the period and the manuscripts are invaluable for anyone interested in studying the British artillery arm in the Peninsula.
Volume I: 1809:
Volume IV:
'the material on the New Orleans campaign of 1815'
It would appear this was published separately for a second time in 1961 in the Louisiana Historical Quarterly. The first time it was published in a journal, it was in the 1920s in the Journal of the Society for Army Historical Research. Fortunately, this can be accessed via JSTOR.