What's an Iron Ranger?

Have you ever heard of an "Iron Ranger?" I hadn't, until yesterday when I entered Fort Ross State Historic Park along U.S. 1 in northern California. Fort Ross, in case you do not know, is where the Russians settled in the 1830s to raise crops and hunt sea otters. But once the animals were virtually wiped out and the crops alone could not justify the expense of the fort, the Russians went home, selling the fort to John Sutter (of Sutter's Fort in Sacramento). Anyway. . . an Iron Ranger, I learned, is the "Pay Box" where you deposit your entry fee.