"I'll bring the banjo along one of these days right enough," he smiled. "Perhaps you'll make a trip down to Gatun and hear one of our concerts. They tell me there's to be one within a few days." Hundley eagerly accepted the invitation, and then proceeded to instruct our hero. As to the latter, he found no great difficulty in understanding the work, and, indeed, in taking charge of the machine. For here it was not quite as it was with a hundred-ton digger, when the lip of the huge shovel might in some unexpected moment cut its way beneath a mass of rock, and be brought up short with a jerk capable of doing great damage. The rock drill, on the other hand, pounded away, the engine revolving the drill, while the crew of the machine saw that the gears were thrown out when necessary, and an extra length added to the drill. If the hardened-steel point of the instrument happened to catch--as was sometimes the case--and held up the engine, then steam had to be cut off quickly, the drill reversed and lifted, so as to allow it to begin afresh. "You never know what's goin' to happen," explained Hundley; "but most times things is clear and straightforward. You lengthen the drill till you've run down about 30 feet: that means eight hours' solid work--a day's full work, Jim. You don't see the real result till the next morning; but my, how those dynamite shots do rip the place about! For instance, jest here where we're sinkin' the drill we're yards from the edge of the step we're working on. Well now, that shot'll be rammed home, and the hole plugged over it. Something's got to go when dynamite is exploded, and sense there's all this weight of stuff to the outside of the terrace, and the shot is 30 feet deep, the outer lip gives way, and jest this boring results in tons of rock and dirt being broken adrift. It's when you see the huge mass of loose stuff next morning that you realize that you ain't been doin' nothin'." At the end of a week Jim was placed in entire charge of a rock drill, while a negro was allocated to the machine to help him. Then, somewhat later than the official had intimated, the motor driller was completed, and our hero was drafted to the Gorgona works for some days, to practise with the implement and get thoroughly accustomed to it. It was a proud day when he occupied the driving seat, threw out his clutch, and set the gears in mesh. Then, the engine buzzing swiftly, and a light cloud of steam coming from the nozzle of the radiator--for, like all rapidly moving motor engines designed for stationary work, the water quickly heated--he set the whole affair in motion, and trundled along the highroad towards the cut. "If you don't make a tale of this machine I shall be surprised," said the official, as he bade him farewell. "This motor should get through the rock very quickly, quicker a great deal than the steam-driven ones. But go steady along the road; steering ain't so easy."