Sentence:  But then I had the [massive] flintlock by me for protection. ¶...The linen-press and a chest on the top of it formed, however, a very good gun-carriage; and, thus <WSD>mounted</WSD>, aim could be taken out of the window at the old mare feeding in the meadow below by the brook, and a 'bead' could be drawn upon Molly, the dairymaid, kissing the fogger behind the hedge,nb.... 
Meaning of the word marked with <WSD> tags:  To attach (an object) to a support, backing, framework etc.