Part 7 (1/2)

Perhaps only sixty. The pressure of this water against it must be tremendous.”

”Of course,” said Uncle d.i.c.k thoughtfully; ”but you forget the shape of the wall, Jack. It is like an elongated pyramid: broad at the base and coming up nearly to a point.”

”No,” said Uncle Jack, ”I've not forgotten all that. Of course it is all the stronger for it, the wider the base is made. But I'm not satisfied, and if I had made this dam I should have made this wall twice as thick or three times as thick; and I don't know that I should have felt satisfied with its stability then.”

”Well done, old conscientious!” cried Uncle Bob, laughing. ”Let's get on.”

”Stop a moment,” I cried. ”Uncle d.i.c.k said he would show us our engine.”

”Well, there it is,” said Uncle d.i.c.k, pointing to the dammed-up lake.

”Isn't it powerful enough for you. This reservoir was made by a water company to supply all our little dams, and keep all our mills going. It gathers the water off the moorlands, saves it up, and lets us have it in a regular supply. What would be the consequences of a burst, Jack?” he said, turning to his brother.

”Don't talk about it man,” said Uncle Jack frowning. ”Why, this body of water broken loose would sweep down that valley and scour everything away with it--houses, mills, rocks, all would go like corks.”

”Why, it would carry away our works, then,” I cried. ”The place is right down by the water side.”

”I hope not,” said Uncle Jack. ”No I should say the force would be exhausted before it got so far as that, eight or nine miles away.”

”Well, it does look dangerous,” said Uncle Bob. ”The weight must be tremendous. How would it go if it did burst?”

”I say, uncle, I'm only a coward, please. Hadn't we better go off here?”

They all laughed, and we went on across the dam.

”How would it go!” said Uncle Jack thoughtfully. ”It is impossible to say. Probably the water would eat a little hole through the top somewhere and that would rapidly grow bigger, the water pouring through in a stream, and cutting its way down till the solidity of the wall being destroyed by the continuity being broken great ma.s.ses would crumble away all at once, and the pent-up waters would rush through.”

”And if they came down and washed away our works just as we were making our fortunes, you would say I was to blame for taking such a dangerous place.”

”There, come along,” cried Uncle Bob, ”don't let's meet troubles half-way. I want a ramble over those hills. There, Cob, now we're safe,” he said, as we left the great dam behind. ”Now, then, who's for some lunch, eh?”

This last question was suggested by the sight of a snug little village inn, where we had a hearty meal and a rest, and then tramped off to meet with an unexpected adventure among the hills.

As soon as one gets into a hilly country the feeling that comes over one is that he ought to get up higher, and I had that sensation strongly.

But what a glorious walk it was! We left the road as soon as we could and struck right away as the crow flies for one of several tremendous hills that we saw in the distance. Under our feet was the purple heath with great patches of whortleberry, that tiny shrub that bears the little purply grey fruit. Then there was short elastic wiry gra.s.s and orange-yellow bird's-foot trefoil. Anon we came to great patches of furze of a dwarf kind with small p.r.i.c.kles, and of an elegant growth, the purple and yellow making the place look like some vast wild garden.

”We always seem to be climbing up,” said Uncle d.i.c.k.

”When we are not sliding down,” said Uncle Jack, laughing.

”I've been looking for a bit of level ground for a race,” said Uncle Bob. ”My word! What a wild place it is!”

”But how beautiful!” I cried, as we sat down on some rough blocks of stone, with the pure thyme-scented air blowing on our cheeks, larks singing above our heads, and all around the hum of insects or bees hurrying from blossom to blossom; while we saw the gra.s.shoppers slowly climbing up to the top of some strand of gra.s.s, take a look round, and then set their spring legs in motion and take a good leap.

”What a difference in the hills!” said Uncle Jack, looking thoughtfully from some that were smooth of outline to others that were all rugged and looked as if great jagged ma.s.ses of stone had been piled upon their tops.

”Yes,” said Uncle d.i.c.k. ”Two formations. Mountain limestone yonder; this we are on, with all these rough pieces on the surface and sticking out everywhere, is millstone-grit.”

”Which is millstone-grit?” I cried.