However； the old overman must well know that such a discovery would be the one thing in the world to interest me； and this invitation； which I must keep secret； to repair to the Dochart pit！〃 James Starr always came back to that。
On the other hand； the engineer knew Ford to be a clever miner； peculiarly endowed with the instinct of his trade。 He had not seen him since the time when the Aberfoyle colliery was abandoned； and did not know either what he was doing or where he was living； with his wife and his son。 All that he now knew was； that a rendezvous had been appointed him at the Yarrow shaft； and that Harry； Simon Ford's son； was to wait for him during the whole of the next day at the Callander station。
〃I shall go； I shall go！〃 said Starr； his excitement increasing as the time drew near。
Our worthy engineer belonged to that class of men whose brain is always on the boil； like a kettle on a hot fire。 In some of these brain kettles the ideas bubble over； in others they just simmer quietly。 Now on this day； James Starr's ideas were boiling fast。
But suddenly an unexpected incident occurred。 This was the drop of cold water； which in a moment was to condense all the vapors of the brain。 About six in the evening； by the third post； Starr's servant brought him a second letter。 This letter was enclosed in a coarse envelope； and evidently directed by a hand unaccustomed to the use of a pen。 James Starr tore it open。 It contained only a scrap of paper； yellowed by time； and apparently torn out of an old copy book。
On this paper was written a single sentence； thus worded：
〃It is useless for the engineer James Starr to trouble himself； Simon Ford's letter being now without object。〃
No signature。
CHAPTER II ON THE ROAD
THE course of James Starr's ideas was abruptly stopped； when he got this second letter contradicting the first。
〃What does this mean？〃 said he to himself。 He took up the torn envelope； and examined it。 Like the other； it bore the Aberfoyle postmark。 It had therefore e from the same part of the county of Stirling。 The old miner had evidently not written it。 But； no less evidently； the author of this second letter knew the overman's secret； since it expressly contradicted the invitation to the engineer to go to the Yarrow shaft。
Was it really true that the first munication was now without object？ Did someone wish to prevent James Starr from troubling himself either uselessly or otherwise？ Might there not be rather a malevolent intention to thwart Ford's plans？
This was the conclusion at which James Starr arrived； after mature reflection。 The contradiction which existed between the two letters only wrought in him a more keen
desire to visit the Dochart pit。 And besides； if after all it was a hoax； it was well worth while to prove it。 Starr also thought it wiser to give more credence to the first letter than to the second； that is to say； to the request of such a man as Simon Ford； rather than to the warning of his anonymous contradictor。
〃Indeed；〃 said he； 〃the fact of anyone endeavoring to influence my resolution； shows that Ford's munication must be of great importance。 To…morrow； at the appointed time； I shall be at the rendezvous。〃
In the evening； Starr made his preparations for departure。 As it might happen that his absence would be prolonged for some days； he wrote to Sir W。 Elphiston； President of the Royal Institution； that he should be unable to be present at the next meeting of the Society。 He also wrote to excuse himself from two or three engagements which he had made for the week。 Then； having ordered his servant to pack a traveling bag； he went to bed； more excited than the affair perhaps warranted。
The next day； at five o'clock； James Starr jumped out of bed； dressed himself warmly； for a cold rain was falling； and left his house in the Canongate； to go to Granton Pier to catch the steamer； which in three hours would take him up the Forth as far as Stirling。
For the first time in his life； perhaps； in passing along the Canongate； he did NOT TURN TO LOOK AT HOLYROOD； the palace of the former sovereigns of Scotland。 He did not notice the sentinels who stood before its gateways； dressed in the uniform of their Highland regiment； tartan kilt； plaid and sporran plete。 His whole thought was to reach Callander where Harry Ford was supposedly awaiting him。
The better to understand this narrative； it will be as well to hear a few words on the origin of coal。 During the geological epoch； when the terrestrial spheroid was still in course of formation； a thick atmosphere surrounded it； saturated with watery vapors； and copiously impregnated with carbonic acid。 The vapors gradually condensed in diluvial rains； which fell as if they had leapt from the necks of thousands of millions of seltzer water bottles。 This liquid； loaded with carbonic acid； rushed in torrents over a deep soft soil； subject to sudden or slow alterations of
form； and maintained in its semi…fluid state as much by the heat of the sun as by the fires of the interior mass。 The internal heat had not as yet been collected in the center of the globe。 The terrestrial crust； thin and inpletely hardened； allowed it to spread through its pores。 This caused a peculiar form of vegetation； such as is probably produced on the surface of the inferior plas； Venus or Mercury； which revolve nearer than our earth around the radiant sun of our system。
The soil of the continents was covered with immense forests。 Carbonic acid； so suitable for the development of the vegetable kingdom； abounded。 The feet of these trees were drowned in a sort of immense lagoon； kept continually full by currents of fresh and salt waters。 They eagerly assimilated to themselves the carbon which they； little by little； extracted from the atmosphere； as yet unfit for the function of life； and it may be said that they were destined to store it； in the form of coal； in the very bowels of the earth。
It was the earthquake period； caused by internal convulsions； which suddenly modified the unsettled features of the terrestrial surface。 Here； an intumescence which was to bee a mountain； there； an abyss which was to be filled with an ocean or a sea。 There； whole forests sunk through the earth's crust； below the unfixed strata； either until they found a resting…place； such as the primitive bed of granitic rock； or； settling together in a heap； they formed a solid mass。
As the waters were contained in no bed； and were spread over every part of the globe； they rushed where they liked； tearing from the scarcely…formed rocks material with which to pose schists； sandstones； and limestones。 This the roving waves bore over the submerged and now peaty forests； and deposited above them the elements of rocks which were to superpose the coal strata。 In course of time； periods of which include millions of years； these earths hardened in layers； and enclosed under a thick carapace of pudding…stone； schist； pact or friable sandstone； gravel and stones； the whole of the massive forests。
And what went on in this gigantic crucible； where all this vegetable matter had accumulated； sunk to various depths？ A regular chemical operation； a sort of distillation。 All the carbon contained in these vegetables had agglomerated； and little by little coal was forming under the double influence of enormous pressure and the high temperature maintained by the internal fires； at this time so close to it。
Thus there was one kingdom substituted for another in this slow but irresistible reaction。 The vegetable was transformed into a mineral。 Plants which had lived the vegeta…tive life in all the vigor of first creation became petrified。 Some of the substances enclosed in this vast herbal left their impression on the other more rapidly mineralized products； which pressed them as an hydraulic press of incalculable power would have done。
Thus also shells； zoophytes； star…fish； polypi； spirifores； even fish and lizards brought by the water； left on the yet soft coal their exact likeness； 〃admirably taken off。〃
Pressure seems to have played a considerable part in the formation of carboniferous strata。 In fact； it is to its degree of power that are due the different sorts of coal； of which industry makes use。 Thus in the lowest layers of the coal ground appears the anthracite； which； being almost destitute of volatile matter； contains the greatest quantity of carbon。 In the higher beds are found； on the contrary； lignite and fossil wood； substances in which the quantity of carbon is infinitely less。 Between these two beds； according to the degree of pressure to which they have been subjected； are found veins of graphite and rich or poor coal。 It may be asserted that it is for want of sufficient pressure that beds of peaty bog have not been pletely changed into coal。 So then； the origin of coal mines； in whatever part of the globe they have been discovered； is this： the absorption through the terrestrial crust of the great forests of the geological period； then； the mineralization of the vegetables obtained in the course of time； under the influence of pressure and heat； and under the action of carbonic acid。
Now； at the time when the events related in this story took place； some of the most important mines of the Scottish coal beds had been exhausted by too rapid working。 In the region which extends between Edinburgh and Glasgow； for a distance of ten or twelve miles； lay the Aberfoyle colliery； of which the engineer； James Starr； had so long
directed the works。 For ten years these mines had been abandoned。 No new seams had been discovered； although the soundings had been carried to a depth of fifteen hundred or even of two thousand feet； and when James Starr had retired； it was with the full conviction that even the smallest vein had been pletely exhausted。
Under these circumstances； it was plain that the discovery of a new seam of coal would be an important event。 Could Simon Ford's munication relate to a fact of this nature？ This question James Starr could not cease asking himself。 Was he called to make conquest of another corner of these rich treasure fields？ Fain would he hope it was so。
The second letter had for an instant chec