the error occurred in this way: the trail that the boys had been assiduously following was so faintly marked that the wonder was they did not go astray sooner. in many places, there was little choice as to the route, because it was so broken and crossed that one was as distinct as the other. nevertheless, frank pressed on with scarcely any hesitation, until he again reached a depression where the soft ground failed to show the slightest impression of shoe or hoof.

"my gracious!" he exclaimed, stopping short and looking at his companion; "how far can we have gone wrong?"

"we can find out only by returning," replied roswell, wheeling about and leading the way back.

they walked more hurriedly than before, as a person naturally does who feels that time is precious, and he has wasted a good deal of it.

the search might have been continued for a long time but for a surprising and unexpected aid that came to them. they had halted at one of the broken places, in doubt whither to turn, and searching for some sign to guide them, when roswell called out:

"that beats anything i ever saw!"

as he spoke, he stooped and picked up something from the ground. inspecting it for a moment, he held it up for frank to see. it was a large nugget of pure gold.

"these mountains must be full of the metal," said frank, "when we find it lying loose like that."

"not so fast," remarked his companion, who had taken the nugget again, and was turning it over and examining it minutely. "do you remember that?"

on one of the faces of the gold something had been scratched with the point of a knife. while the work was inartistic, it was easy to make out the letters "f. m."

"i think i remember that," said frank; "it is one of the nuggets i found yesterday, and marked it with my initials. those folks must have dropped it."

there could be no doubt of it. what amazing carelessness for a couple of men to drop a chunk of gold worth several hundred dollars and not miss it!

it must have been that the mouth of the canvas bag containing the nuggets had become opened in some way to the extent of allowing a single one to fall out.

"i wonder how many more have been lost," mused frank, as he put the specimen in his pocket.

at any rate, it served to show the right course to follow, and the boys pressed on, looking more for nuggets than for their enemies. the mishap must have been discovered by the men in time to prevent its repetition, for nothing of the kind again met the eyes of the youths, who once more gave their attention to hunting for the lawless men that had despoiled them of so much property.

the trail steadily ascended, so broken and rough that it was a source of constant wonderment how the burro was able to keep his feet. he must have had some experience in mountain climbing before, in order to play the chamois so well.

the boys fancied they could feel the change of temperature on account of the increased elevation. they knew they were a good many feet above the starting-point, though at no time were they able to obtain a satisfactory view of the country they were leaving behind. they seemed to be continually passing in and out among the rocks and bowlders, which circumscribed their field of vision. considerable pine and hemlock grew on all sides, but as yet they encountered no snow. there was plenty of it farther up and beyond, and it would not take them long to reach the region where eternal winter reigned.

a short way along the new course, and they paused before another break; but although the ground was dry and hard, it was easy to follow the course of the burro, whose hoofs told the story; and though nothing served to indicate that the men were still with him, the fact of the three being in company might be set down as self-evident.

it would not be dark until nearly 10 o'clock, so the pursuers still had a goodly number of hours before them.

a peculiar fact annoyed the boys more than would be supposed. the trail was continually winding in and out, its turns so numerous that rarely or never were they able to see more than a few rods in advance. in places the winding was incessant. the uncertainty as to how far they were behind the donkey and the men made the lads fear that at each turn as they approached it, they would come upon the party, who, perhaps, might be expecting them, and would thus take them unprepared. the dread of something like this often checked the boys and seriously retarded their progress.

"we may as well understand one thing," said frank, as they halted again; "you have heard jeff tell about getting the drop on a man, roswell?"

"yes; everybody knows what that means."

"well, neither mr. hardman, nor his friend, nor both of them will ever get the drop on us."

the flashing eyes and determined expression left no doubt of the lad's earnestness.

"is that because you carry a winchester and they have only their revolvers?"

"it would make no difference if both of them had rifles."

roswell was thoughtful.

"it is very well, frank, to be brave, but there's nothing gained by butting your head against a stone wall. suppose, now, that, in passing the next bend in this path, you should see hardman waiting for you with his gun aimed, and he should call out to you to surrender, what would you do?"

"let fly at him as quickly as i could raise my gun to a level."

"and he would shoot before you could do that."

"i'll take the chances," was the rash response.

"i hope you will not have to take any chances like that—"

they were talking as usual in low tones, and no one more than a few feet away could have caught the murmur of their voices, but while roswell was uttering his words, and before he could complete his sentence, the two heard a sound, so faint that neither could guess its nature.

as nearly as they were able to judge, it was as if some person, in walking, had struck his foot against an obstruction. it came from a point in front, and apparently just beyond the first bend in the trail, over which they were making their way.

watching at the turn in the trail.

watching at the turn in the trail.

"we are nearer to them than we suspected," whispered roswell.

"and they don't know it, or they wouldn't have betrayed themselves in that manner."

"it isn't safe to take that for granted."

roswell, after the last change in their course, was at the front. frank now quietly moved beyond him, winchester in hand, and ready for whatever might come. confident they were close upon the men they sought, he was glad of the misstep that had warned them of the fact.

there certainly could be no excuse now for hardman and his companion securing the advantage over the boys, when one of them held his winchester half raised to his shoulder and ready to fire.

within a couple of paces of the turn in the trail the two were almost lifted off their feet by a sound that burst from the stillness, startling enough to frighten the strongest man. it was the braying of the burro, not fifty feet distant.