 Complete the following phrase:  In 1868, the first version of his machine-gun was finished and a demonstration of its capacity was held on Ladugårdsgärdet, Stockholm in front of the Swedish Defense Minister; G.R. Abel. After a couple of modifications and improvements, he patented the multi-barrel, lever-actuated, machine gun and it was bought into the Swedish army. Same year, the machine-gun was shown on the 