Please note for your safety:There is no parking on Hobart Avenue near this spot, and the traffic can be heavy.
The easiest, and safest, thing to do is park on Beacon Road, and then walk around the corner to the Old Sow plaque. As is visible in the picture above, there is a grass path, so that you don't have to walk in the street.
The plaque reads:
'"Here in the time of the American Revolution stood the Signal Beacon and by its side the cannon known as the 'Old Sow', which in time of danger and invasion summoned the patriotic 'Minute Men' of this vicinity to the defense of the country and the repulse of the invader." 
1.^ The monument states: "This monument was erected by the New Jersey Society of the Sons of the American Revolution and dedicated to the memory of the Patriots of New Jersey Removed to this spot from its location and re-dedicated July 4th 1908."
Revolutionary War New Jersey
An online guide to discovering the role of New Jersey in the Revolutionary War and the nation's founding.
Summit New Jersey Revolutionary War Sites • Summit New Jersey Historic Sites
Old Sow Plaque