These manuscripts provide a detailed account of the voyage Blot undertook for the Bureau des Longitudes who were researching a new magnetic chart of the globe. This was a major project for the Bureau at the time, resulting in several expeditions, with a view to filling in the blanks of the known variations in the Earth's magnetic fields.
Blot's first official 'Memoire' on the voyage gives a detailed overview and includes: an introduction about the mission, preparations and observations, survey of Cochinchine, observations and survey of Batavia, survey of the Australian East coast (Brisbane and Sydney) and his return voyage. The letter accompanying the report to the President of the Bureau des Longitudes, dated 10 April 1896, further elaborates on Blot's findings.
The second report, on official 'Mission Magnetique' letterhead and noted as a copy is the account of the voyage prepared for the Ministre de la Marine. This report gives extra details of the voyage. It appears to be in a secretarial hand but to have been signed by Blot himself at the conclusion.
The mission was quite abruptly aborted in 1896. Blot mentions that upon his arrival in Brisbane he received a message via the French consular agent, reading: "Blot, Monaque, partis Brisbane. Mission supprimee. Ordre rentrer immediatement".
The Bureau did publish a lengthy monograph on their findings as 'Missions magnetiques organisees par le Bureau des longitudes en 1895-1896' (Paris, Gaulthier-Villars, 1903).