Answer:
I believe it's "Barreled cannon (the automatic weapon)".
Step-by-step explanation:
Leonardo was heavily preoccupied by the inadequacies of contemporary warfare, frustrated particularly by the time-lag between rounds of cannon fire, caused by the necessity to reload. Leonardo devised a multi-barreled cannon that could be rotated to fire a line of cannons whilst another was being reloaded: a primitive ancestor of the modern day machine gun.
Evidence:
I believe it's "Cannons from a late 15th century/early 16th century drawing as shown in The Life and Times of Leonardo, Paul Hamlyn."
Hope I helped!
Have a good day. =)