Monmouth's 'machine gun'

This story of the Duke of Monmouth being offered a multi-barrelled gun is interesting.
From
The Life, Progresses, and Rebellion of James, Duke of Monmouth by George Roberts (1844)
The proverb is true, that "there is no new thing under the sun." Every day brings to light facts which prove that what have been deemed new discoveries were, many of them, known and practised in former years.
In the century whose events this history portrays there was an office held by Captain Silver, who was styled the master-gunner of England, and whose province embraced those many artifices for the destruction of human life which excited confidence and admiration in those who possessed them, but which are now considered in the light of toys, since the art and practice of war is so much better understood. This master-gunner had a brother, who was of Bridgwater, and was of kindred genius with himself—perhaps desired to emulate his brother's fame. He invented a machine, which he offered to the Duke of Monmouth, to be used in his cause in the defence of that place against the King's army. Silver's discovery consisted in the arrangement of many musket-barrels, which were to be discharged at once, sweeping any narrow entrance of the town through which the King's troops might advance.
Oldmixon, who was led into the erroneous belief that the Duke would make a stand at Bridgwater, accounts for his not adopting this substitute for cannon, owing to the absence of the noise of great guns, which was, it seems, considered necessary to inspire confidence in raw soldiers.
It now appears that there is a machine in the arsenal of Vienna, bearing date 1678, by which fifty muskets could be discharged in any direction, and at any angle, by the application of a single match. Silver had probably heard of this.