caught a dull sound； like a distant murmur。 His panions were not long in hearing it themselves。 It was above their heads； a sort of rolling sound； in which though it was so feeble； the successive CRESCENDO and DIMINUENDO could be distinctly heard。
All four stood for some minutes； their ears on the stretch； without uttering a word。 All at once Simon Ford exclaimed； 〃Well； I declare！ Are trucks already running on the rails of New Aberfoyle？〃
〃Father；〃 replied Harry； 〃it sounds to me just like the noise made by waves rolling on the sea shore。〃
〃We can't be under the sea though！〃 cried the old overman。
〃No；〃 said the engineer； 〃but it is not impossible that we should be under Loch Katrine。〃
〃The roof cannot have much thickness just here； if the noise of the water is perceptible。〃
〃Very little indeed；〃 answered James Starr； 〃and that is the reason this cavern is so huge。〃
〃You must be right； Mr。 Starr；〃 said Harry。
〃Besides； the weather is so bad outside；〃 resumed Starr； 〃that the waters of the loch must be as rough as those of the Firth of Forth。〃
〃Well！ what does it matter after all？〃 returned Simon Ford； 〃the seam won't be any the worse because it is under a loch。 It would not be the first time that coal has been looked for under the very bed of the ocean！ When we have to work under the bottom of the Caledonian Canal； where will be the harm？〃
〃Well said； Simon；〃 cried the engineer； who could not restrain a smile at the overman's enthusiasm； 〃let us cut our trenches under the waters of the sea！ Let us bore the bed of the Atlantic like a strainer； let us with our picks join
our brethren of the United States through the subsoil of the ocean！ let us dig into the center of the globe if necessary； to tear out the last scrap of coal。〃
〃Are you joking； Mr。 Starr？〃 asked Ford； with a pleased but slightly suspicious look。
〃I joking； old man？ no！ but you are so enthusiastic that you carry me away into the regions of impossibility！ e； let us return to the reality； which is sufficiently beautiful； leave our picks here； where we may find them another day； and let's take the road back to the cottage。〃
Nothing more could be done for the time。 Later； the engineer； acpanied by a brigade of miners； supplied with lamps and all necessary tools； would r閟um？the exploration of New Aberfoyle。 It was now time to return to the Dochart pit。 The road was easy； the gallery running nearly straight through the rock up to the orifice opened by the dynamite； so there was no fear of their losing themselves。
But as James Starr was proceeding towards the gallery Simon Ford stopped him。
〃Mr。 Starr；〃 said he； 〃you see this immense cavern； this subterranean lake； whose waters bathe this strand at our feet？ Well！ it is to this place I mean to change my dwelling； here I will build a new cottage； and if some brave fellows will follow my example； before a year is over there will be one town more inside old England。〃
James Starr； smiling approval of Ford's plans； pressed his hand； and all three； preceding Madge； re…entered the gallery； on their way back to the Dochart pit。 For the first mile no incident occurred。 Harry walked first； holding his lamp above his head。 He carefully followed the principal gallery； without ever turning aside into the narrow tunnels which radiated to the right and left。 It seemed as if the returning was to be acplished as easily as the going； when an unexpected accident occurred which rendered the situation of the explorers very serious。
Just at a moment when Harry was raising his lamp there came a rush of air； as if caused by the flapping of invisible wings。 The lamp escaped from his hands； fell on the rocky ground； and was broken to pieces。
James Starr and his panions were suddenly plunged in absolute darkness。 All the oil of the lamp was spilt； and it was of no further use。 〃Well； Harry；〃 cried his father；
〃do you want us all to break our necks on the way back to the cottage？〃
Harry did not answer。 He wondered if he ought to suspect the hand of a mysterious being in this last accident？ Could there possibly exist in these depths an enemy whose unaccountable antagonism would one day create serious difficulties？ Had someone an interest in defending the new coal field against any attempt at working it？ In truth that seemed absurd； yet the facts spoke for themselves； and they accumulated in such a way as to change simple presumptions into certainties。
In the meantime the explorers' situation was bad enough。 They had now； in the midst of black darkness； to follow the passage leading to the Dochart pit for nearly five miles。 There they would still have an hour's walk before reaching the cottage。
〃e along；〃 said Simon Ford。 〃We have no time to lose。 We must grope our way along； like blind men。 There's no fear of losing our way。 The tunnels which open off our road are only just like those in a molehill； and by following the chief gallery we shall of course reach the opening we got in at。 After that； it is the old mine。 We know that； and it won't be the first time that Harry and I have found ourselves there in the dark。 Besides； there we shall find the lamps that we left。 Forward then！ Harry； go first。 Mr。 Starr； follow him。 Madge； you go next； and I will bring up the rear。 Above everything； don't let us get separated。〃
All plied with the old overman's instructions。 As he said； by groping carefully； they could not mistake the way。 It was only necessary to make the hands take the place of the eyes； and to trust to their instinct； which had with Simon Ford and his son bee a second nature。
James Starr and his panions walked on in the order agreed。 They did not speak； but it was not for want of thinking。 It became evident that they had an adversary。 But what was he； and how were they to defend themselves against these mysteriously…prepared attacks？ These disquieting ideas crowded into their brains。 However； this was not the moment to get discouraged。
Harry； his arms extended； advanced with a firm step； touching first one and then the other side of the passage。
If a cleft or side opening presented itself； he felt with his hand that it was not the main way； either the cleft was too shallow； or the opening too narrow； and he thus kept in the right road。
In darkness through which the eye could not in the slightest degree pierce； this difficult return lasted two hours。 By reckoning the time since they started； taking into consideration that the walking had not been rapid； Starr calculated that he and his panions were near the opening。 In fact； almost immediately； Harry stopped。
〃Have we got to the end of the gallery？〃 asked Simon Ford。
〃Yes；〃 answered the young miner。
〃Well！ have you not found the hole which connects New Aberfoyle with the Dochart pit？〃
〃No；〃 replied Harry； whose impatient hands met with nothing but a solid wall。
The old overman stepped forward； and himself felt the schistous rock。 A cry escaped him。
Either the explorers had strayed from the right path on their return； or the narrow orifice； broken in the rock by the dynamite； had been recently stopped up。 James Starr and his panions were prisoners in New Aberfoyle。
CHAPTER IX THE FIRE…MAIDENS
A WEEK after the events just related had taken place； James Starr's friends had bee very anxious。 The engineer had disappeared； and no reason could be brought forward to explain his absence。 They learnt； by questioning his servant； that he had embarked at Granton Pier。 But from that time there were no traces of James Starr。 Simon Ford's letter had requested secrecy； and he had said nothing of his departure for the Aberfoyle mines。
Therefore in Edinburgh nothing was talked of but the unaccountable absence of the engineer。 Sir W。 Elphiston； the President of the Royal Institution； municated to his colleagues a letter which James Starr had sent him； excusing himself from being present at the next meeting of the society。 Two or three others produced similar letters。 But
though these documents proved that Starr had left Edinburgh…… which was known before……they threw no light on what had bee of him。 Now； on the part of such a man； this prolonged absence； so contrary to his usual habits； naturally first caused surprise； and then anxiety。
A notice was inserted in the principal newspapers of the United Kingdom relative to the engineer James Starr； giving a description of him and the date on which he left Edinburgh； nothing more could be done but to wait。 The time passed in great anxiety。 The scientific world of England was inclined to believe that one of its most distinguished members had positively disappeared。 At the same time； when so many people were thinking about James Starr； Harry Ford was the subject of no less anxiety。 Only； instead of occupying public attention； the son of the old overman was the cause of trouble alone to the generally cheerful mind of Jack Ryan。
It may be remembered that； in their encounter in the Yarrow shaft； Jack Ryan had invited Harry to e a week afterwards to the festivities at Irvine。 Harry had accepted and promised expressly to be there。 Jack Ryan knew； having had it proved by many circumstances； that his friend was a man of his word。 With