ks that you found out the fire…damp？〃 asked James Starr。
〃Just there； sir；〃 returned Ford； 〃and I was able to light it only by bringing my lamp near to the cracks in the rock。 Harry has done it as well as I。〃
〃At what height？〃 asked Starr。
〃Ten feet from the ground；〃 replied Harry。
James Starr had seated himself on a rock。 After critically inhaling the air of the cavern； he gazed at the two miners； almost as if doubting their words； decided as they were。 In fact； carburetted hydrogen is not pletely scentless； and the engineer； whose sense of smell was very keen； was astonished that it had not revealed the presence of the explosive gas。 At any rate； if the gas had mingled at all with the surrounding air； it could only be in a very small stream。 There was no danger of an explosion； and they might without fear open the safety lamp to try the experiment； just as the old miner had done before。
What troubled James Starr was； not lest too much gas
mingled with the air； but lest there should be little or none。
〃Could they have been mistaken？〃 he murmured。 〃No： these men know what they are about。 And yet……〃
He waited； not without some anxiety； until Simon Ford's phenomenon should have taken place。 But just then it seemed that Harry； like himself； had remarked the absence of the characteristic odor of fire…damp； for he exclaimed in an altered voice； 〃Father； I should say the gas was no longer escaping through the cracks！〃
〃No longer！〃 cried the old miner……and； pressing his lips tight together； he snuffed the air several times。
Then； all at once； with a sudden movement； 〃Hand me your lamp； Harry；〃 he said。
Ford took the lamp with a trembling hand。 He drew off the wire gauze case which surrounded th