“There are two tunnels through the Narrow Ridge, each sixteen feet horizontal by eight in height; one in use driving a small mill; the other, two hundred and twenty-six feet distant, purposely left incomplete by a thin web of rock to shut off the flow of water. This power and the land combined presents a peculiar opportunity to the manufacturer for investing in a property that furnishes both the raw material and the most economical and convenient means of working it into commercial form.”