"The Gulf of Mexico," echoed the two Ethels. Then they added, also together, "So you can!" and Ethel Brown said, "The Indians used to go from the upper end of Lake Chautauqua to the Gulf in their canoes? When they got to Fort Duquesne it was easy paddling."

"What is that high wharf with a building on it overhanging the river?"

asked Helen.

"That's a coal tipple," said her grandfather. "Do you see on sh.o.r.e some low-lying houses and sheds? They are the various machinery plants and offices of the coal mine and that double row of small houses a quarter of a mile farther up is where the employes live."

As the boat continued up the river it pa.s.sed many such tipples. They were now in the soft coal country, the steersman said, and in due time they arrived at Millsboro, a little town about ten miles above Brownsville.

Here Mr. Emerson made immediate inquiries about Stanley Clark, and found that he had gone on, leaving "Uniontown, Fayette County," as his forwarding address. "That's the county seat where Hapgood says he copied his records," said Mr. Emerson. "I hope we shall catch young Clark there and get that matter straightened out."

As there was no train to Uniontown until the afternoon, Mr. Emerson engaged a motor car to take them to a large mine whose tipple they had pa.s.sed on the way up. The Superintendent was a friend of the driver of the car and he willingly agreed to show them through. Before entering the mine he pointed out to them samples of coal which he had collected.

Some had fern leaves plainly visible upon their surfaces and others showed leaves of trees and shrubs.

"Fairy pencilings, a quaint design, Veinings, leaf.a.ge, fibers clear and fine,"

quoted Ethel Blue softly, as she looked at them.

Mrs. Morton stopped before a huge block of coal weighing several tons and said to her son, "Here's a lump for your furnace, Roger."

"Phew," said Roger. "Think of a furnace large enough to fit that lump!

Do you get many of them?" he asked of the Superintendent.

"We keep that," said the Superintendent, "because it's the largest single lump of coal ever brought out of this mine. Of course, we could get them if we tried to, but it's easier to handle it in smaller pieces."

"What'th in that little houthe over there?" asked d.i.c.ky. "Theems to me I thee something whithing round."

"That's the fan that blows fresh air into the mine so that the miners can breathe, and drives out the poisonous and dangerous gases."

"What would happen if the fan stopped running?" asked Ethel Brown.

"Many things might happen," said the Superintendent gravely. "Men might suffocate for lack of air, or an explosion might follow from the collection of the dreaded 'fire damp' ignited by some miner's lamp."

"Fire damp?" repeated Mrs. Morton. "That is really natural gas, isn't it?"

"Yes, they're both 'marsh gas' caused by the decay of the huge ferns and plants of the carboniferous age. Some of them hardened into coal and others rotted when they were buried, and the gas was caught in huge pockets. It is gas from these great pockets that people use for heating and cooking all about here and even up into Canada."

Ethel Brown had been listening and the words "some of them hardened into coal" caught her ear. She went close to her grandfather's side.

"Tell me," she said, "exactly what is coal and how did it get here?"

"What _I_ want to know," retorted Mr. Emerson, "is what brand of curiosity you have in your cranium, and how did it get there? Answer me that."

Ethel Brown laughed.

"Let's have a lecture," she urged, "and," handing her grandfather a small lump of coal, "here's your text."

Mr. Emerson turned the bit of coal over and over.

"When I look at this little piece of black stone," he said, "I seem to see dense forests filled with luxuriant foliage and shrubbery and mammoth trees under which move sluggish streams draining the swampy ground. The air is damp and heavy and warm."

"What about the animals?"

"There are few animals. Most of them are water creatures, though there are a few that can live on land and in the water, too, and in the latter part of the coal-making period enormous reptiles crawled over the wet floor of the forest. Life is easy in all this leafy splendor and so is death, but no eye of man is there to look upon it, no birds brighten the dense green of the trees, and the ferns and shrubs have no flowers as we know them. The air is heavy with carbon."

"Where was the coal?"

"The coal wasn't made yet. You know how the soil of the West Woods at home is deep with decayed leaves? Just imagine what soil would be if it were made by the decay of these huge trees and ferns! It became yards and yards deep and silt and water pressed it down and crushed from it almost all the elements except the carbon, and it was transformed into a mineral, and that mineral is coal."

"Coal? Our coal?"

"Our coal. See the point of a fern leaf on this bit?" and he held out the piece of coal he had been holding. "That fern grew millions of years ago."

"Isn't it delicate and pretty!" exclaimed Ethel Blue, as it reached her in pa.s.sing from hand to hand, "and also not as clean as it once was!"

she added ruefully, looking at her fingers.

By way of preparation for their descent into the mine each member of the party was given a cap on which was fastened a small open wick oil lamp.

They did not light them, however, until they had all been carried a hundred feet down into the earth in a huge elevator. Here they needed the illumination of the tiny lamps whose flicker made dancing shadows on the walls.

Following the Superintendent their first visit was to the stable.

"What is a stable doing down here?" wondered Ethel Brown.

"Mules pull the small cars into which the miners toss the coal as they cut it out. These fellows probably will never see the light of day again," and their leader stroked the nose of the animal nearest him which seemed startled at his touch.

"He's almost blind, you see," the Superintendent explained. "His eyes have adjusted themselves to the darkness and even these feeble lights dazzle him."

The girls felt the tears very near their eyelids as they thought of the fate of these poor beasts, doomed never to see the sun again or to feel the gra.s.s under their feet.

"I once knew a mule who was so fond of music that he used to poke his head into the window near which his master's daughter was playing on the piano," said the Superintendent, who noticed their agitation and wanted to amuse them. "We might get up band concerts for these fellows."

"Poor old things, I believe they would like it!" exclaimed Helen.

"This is a regular underground village," commented Mrs. Morton, as they walked for a long distance through narrow pa.s.sages until they found themselves at the heading of a drift where the men were working.

"Is there any gas here?" asked the Superintendent, and when the miners said "Yes," he lifted his hand light, which was encased in wire gauze, and thrust it upwards toward the roof and gave a grunt as it flickered near the top.

There it was, the dreaded fire-damp, in a layer above their heads. One touch of an open flame and there would be a terrible explosion, yet the miners were working undisturbed just beneath it with unprotected lamps on their caps. The visitors felt suddenly like recruits under fire--they were far from enjoying the situation but they did not want to seem alarmed. No one made any protest, but neither did any one protest when the Superintendent led the way to a section of the mine where there was no gas that they might see a sight which he a.s.sured them was without doubt wonderful.

They were glad that they had been a.s.sured that there was no fire-damp here, for their leader lifted his lamp close to the roof. Ethel Blue made the beginning of an exclamation as she saw his arm rising, but she smothered her cry for her good sense told her that this experienced man would not endanger the lives of himself or his guests. The coal had been taken out very cleanly, and above them they saw not coal but shale.

"What is shale?" inquired Helen.

"Hardened clay," replied the Superintendent. "There were no men until long after the carboniferous period when coal was formed, but just in this spot it must have happened that the soil that had gathered above the deposits of coal was very light for some reason or other. Above the coal there was only a thin layer of soft clay. One day a hunter tramped this way and left his autograph behind."

He held his lamp steadily upward, and there in the roof were the unmistakable prints of the soles of a man's feet, walking.

"It surely does look mightily as if your explanation was correct,"

exclaimed Mr. Emerson, as he gazed at the three prints, in line and s.p.a.ced as a walker's would be. Their guide said that there had been six, but the other three had fallen after being exposed to the air.