ver projected: the contractors had taken
for their basis a mountain gorge, with a stream flowing through it
down toward Hillsborough; all they had to do was to throw an embankment
across the lower end of the gorge, and turn it to a mighty basin open to
receive the stream, and the drainage from four thousand acres of hill.
From this lake a sixty-foot wear was to deal out the water-supply to
the mill-owners below, and the surplus to the people of Hillsborough,
distant about eight miles on an easy decline.

Now, as the reservoir must be full at starting, and would then be eighty
feet deep in the center, and a mile long, and a quarter of a mile broad,
on the average, an embankment of uncommon strength was required to
restrain so great a mass of water; and this was what the Hillsborough
worthies were curious about. They strolled out to the works, and then
tea was to come out after them, the weather being warm and soft. Close
to the works they found a foreman of engineers smoking his pipe, and
interrogated him. He showed them a rising wall, five hundred feet wide
at the base, and told them it was to be ninety feet high, narrowing,
gradually, to a summit twelve feet broad. As the whole embankment was to
be twelve hundred feet long at the top, this gave some idea of the
bulk of the materials to be used: those materials were clay, shale,
mill-stone, and sandstone of looser texture. The engineer knew Grotait,
and brought him a drawing of the mighty cone to be erected. "Why, it
will be a mountain!" said Little.

"Not far from that, sir: and yet you'll never see half the work. Why,
we had an army of navvies on it last autumn, and laid a foundation sixty
feet deep and these first courses are all bonded in to the foundation,
and bonded together, as you see. We are down to solid rock, and no
water can get to undermine us. The puddle wall is sixteen feet wide at
starting, and diminishes to four feet at the top: so no water can creep
in through our jacket."

"But what are these apertures?" inquired Grotait.

"Oh, those are the waste-pipes. They pass through the embankment
obliquely, to the wear-dam: they can be opened, or shut, by valves, and
run off ten thousand cubic feet of water a minute."

"But won't that prove a hole in your armor? Why, these pipes must be in
twenty joints, at least."

"Say fifty-five; you'll be nearer the mark."

"And suppose one or two of these fifty-five joints should leak? You'll
have an everlasting so