Admiralty Office 9^th Ap^l 1814

Sir

            I am commanded by my Lords
Commiƒsioners of the Admiralty
to send to you herewith the results
of observations made on board
His Majesty's Ship Invincible
upon the variation of the
Compaƒs, transmitted by Captain
Charles Adam.

        I am
              Sir
                Your very humble serv^t
                Jn Barrow

Captain M Flinders

[Captain Adam's written explanation of his bearings and mathematical observations]

    When the Ships Head was to the Westward the Compaƒs at the Binnacle is 4° to the South^d of the one placed near the middle of the Quarter deck, but when the H^d is to the East^d the diff is the same to the North^d consequently the attraction lies abaft the foremost one, or before the other, & from the observations tho' very irregular (from what cause I have not been able to find out except the Cards being in the Ship since first commiƒsioned & their magnetism not very sensible) the attraction appears abaft also. —— It is evident the stantions [sic] under the half deck effect more than any thing on deck, for the compaƒses placed one over the other over the middle of the deck exactly agree, but one placed on the deck only 12 inches on either side the diff. is more or leƒs than a point according to the distance from the stantion [sic] nearest it. ——— The Marines Arms Cutlaƒses Boarding pikes &^c kept under the Poop being taken away made very little difference. — From the constant {shaking} motion of a Ship in Commiƒsion it is impoƒsible to find the neutral points exactly, —— but by the experiments made it appears to be in this Ship between the Main & Mizen Masts nearly in the middle of the Quarter Deck so that as many stantions are before as abaft the Compaƒs. The other points I have not been able to find out.
        The foregoing observations and researches were made by M^r Ja^s Bennett acting 2^d Master of the Invincible generally under my immediate inspection.
                        Cha^s Adam Captain
20 January 1814