bertie, who had joined harry when he saw dias approaching, had listened silently to their talk, then said:

"don't you think that, by loading the mules and moving towards the mouth of the next gorge just as it is getting dark, we might induce the chincas to think that we are going that way, and so to follow along the top of the hills. we might, as soon as night has fallen, come back again and go down the stream. of course there may be some of them left to watch the mouth of the ravine, but we could drive them off easily enough, and get a long start before the fellows on the hills know what has happened."

none of the others spoke immediately; then harry said:

"the idea is a good one as far as it goes. but you see at present we are in a very strong position. if we leave this and they overtake us in the woods, we shall not have the advantages that we have here."

"yes, i see that, harry; but almost anything is better than having to wait here and lose our chance of finding that gold."

"we can't help that, bertie. you know how much that gold would be to me, but, as i said this morning, i will run no desperate risks to obtain it. when i started upon this expedition i knew that the chances of success were extremely slight, and that there might be a certain amount of danger to encounter from wild beasts and perhaps brigands; but i had never calculated upon such a risk as this, and certainly i am not prepared to accept the responsibility of leading others into it."

there was again silence, which was broken at last by dias.

"the proposal of the young se?or is a very bold one; but, as you say, don harry, after leaving our position we should be followed and surrounded. in the forest that would be very bad. i should say let us wait for at least a week; that will still give us time to reach the gold valley. by then the savages may have left, and some other plan may have occurred to us; at any rate, at the end of a week we shall see how things go. the indians may have made an attack, and may lose heart after they are repulsed. they may find difficulty in procuring food, though i hardly think that is probable. still, many things may occur in a week. if at the end of that time they are still here, we can decide whether to try some such plan as the young se?or has thought of, or whether to wait until the indians leave, and then return to cuzco; for i feel certain that the place cannot be found except by the help of the star."

"well, then," bertie said, "could we not hit upon some plan to frighten them?"

"what sort of plan, bertie?"

"well, of course we could not make a balloon—i mean a fire-balloon—because we have no paper to make it with. if we could, and could let it up at night, with some red and blue fires to go off when it got up high, i should think it would scare them horribly."

"yes; but it would be still better, bertie, if we could make a balloon big enough to carry us and the mules and everything else out of this place, and drop us somewhere about the spot we want to get to."

"oh, it is all very well to laugh, harry! i said, i knew we could not make a fire-balloon; i only gave that as an example. if we had powder enough we might make some rockets, and i should think that would scare them pretty badly."

"yes, but we haven't got powder, bertie. we have plenty of cartridges for sporting purposes, or for fighting; but a rocket is a thing that wants a lot of powder, besides saltpetre and charcoal, and so on."

"yes, yes, i know that," bertie said testily. "my suggestion was that we might frighten them somehow, and i still don't see why we shouldn't be able to do it. let us try to hit upon something else."

"there is a good deal in what the young se?or says," dias said gravely. "all the indians are very superstitious, and think anything they don't understand is magic. it is worth thinking over: but before we do anything else we might find out how many of them there are at the other end of the ravine. only a few may be left, or possibly the whole tribe may be gathered there at nightfall. to-night nothing will be settled, but to-morrow night i will go down the torrent with josé. i will carry your double-barrelled guns with me, se?or, if you will let me have them. when we get to the other end i will take up my station there. josé is small and active. he could crawl forward and ascertain how many of them there are. if he should be discovered, which is not likely, he would run back to me. i should have four barrels ready to pour into them. that would stop them, for they would think we were all there and were going to attack them, and before they could recover from their alarm we should be back here again."

"that seems a good plan, dias; but i do not see why bertie and i should not go down with you."

"it would be better not, se?or. in the first place, they may have men posted at their end of the ravine, and though two of us might crawl down without being seen, just as they crawled up here, they would be more likely to see four; in the next place, they might chance to crawl down the hillside above just as we were going down the ravine, and maria and the animals would be at their mercy."

"they are hardly likely to choose the exact moment when we are to be away, but i quite agree with you that the risk must not be run."

"well," bertie said, returning to his former idea, "if dias can go down there, i still think that somehow we might get up a scare."

harry laughed.

"well, you think it over, bertie. if you can suggest anything, i promise you that dias and i will do our best to carry it out."

"very well," bertie replied gravely, "i will think it over."

"now," harry said, "we had better sleep in watches at night; one must be at the breast-work, and one must listen for noises on the cliffs. it would be hardly possible for a number of men to crawl down without exciting suspicion or putting in motion some small stones."

"i do not think, se?or," dias said, "that it will be necessary to keep that watch, for, as we knew from the noise when you fired last night, there are numbers of birds and at least one beast—i fancy it is a bear from the sound of its roar—up there, and it would be strange if a number of men making their way down did not disturb some of them; indeed, if one bird gave the alarm, it would put them all in motion; besides, there are certainly monkeys, for i heard their cries and chattering when the birds flew up. still, it is perhaps as well that one of us should watch. shall we divide, as we did last night? only, of course, josé takes his place with you."

"i quite agree with you, dias. bertie, you had better get three hours' sleep at once, and then after dinner we will sit by the fire here, smoke, and listen, and dias will watch the gorge and keep one ear open in this direction too. it is a comfort to know that if we cannot get away by going up the stream, the indians cannot get down to attack us from that direction."

two nights and days passed. the indians were still on the hills, and once or twice men came down some distance, but a shot from harry's rifle sent them speedily back again. the third night bertie was on watch; he saw nothing, but suddenly there came three sharp taps. he discharged one barrel of his gun at random down the ravine, and then held himself ready to fire the other as soon as he saw anyone approaching. it was an anxious minute for him before the other three ran up.

"what is it, bertie; have you seen anything?"

"no, but three arrows tapped against the wall, so i fired one barrel to call you up, and have been looking out for someone to take a shot at with the other; but i have not seen anyone, though, as you may imagine, i looked out sharply."

"it is probable that after the lesson they got the other night they did not come so near, and that they merely shot their arrows to see if we were still on guard. however, we may as well stay here for a bit to see if anything comes of it."

nothing happened, however, and they returned to the tents. next morning bertie said to his brother:

"look here, harry, i have been thinking over that plan of mine. i really think there is something to be done with it."

"well, tell us your plan."

"in the first place, how much powder can you spare?"

"there is that great powder-horn josé drags about with him to charge his musket with. it will contain about a couple of pounds, i should say."

"that ought to do, i think."

"well, what is your plan, bertie?"

"in the first place, do you think that burned wood would do for charcoal?"

"it depends on what purpose you want it for."

"i want it to prevent the powder from going off with a bang."

"oh, well, i should think that burned wood ground to a powder would be just as good as charcoal. so you are still thinking of rockets? your two pounds of powder won't make many of them—not above two fair-sized ones, and the betting is they would not go up."

"no, i am not thinking of rockets, but of squibs and crackers. i know when i was at school i made a lot of these, and they worked very well. my idea is that if we could crawl up close to where the indians are assembled, each carrying a dozen squibs and as many crackers, we could light a lot of the crackers first and chuck them among them, and then send the squibs whirling about over their heads, with a good bang at the end. it would set them off running, and they would never stop till they were back in their own forests."

"well, i really do think that that is a fine idea—a splendid idea! the only drawback is, that in order to carry it out we should want a lot of strong cartridge-paper, and we have no paper except our note-books."

"i have thought of that, harry, though it bothered me for a good long time. you see, the cases are only to hold the powder and to burn regularly as the powder does. at first i thought we might find some wood like elder and get the pith out, just as we used to do for pop-guns, but that unfortunately would not burn. we might, however, make them of linen."

"but we have no linen."

"no, but our leather bed-bags are lined with that coarse sort of stuff they cover mattresses with."

"tick, you mean?"

"yes, tick. now, it struck me that this would do for the crackers. we should have to cut it in strips three or four times the width of the cracker. then we could get maria to make us some stiff paste; starch would be better, but of course we have none. then, taking a strip of the cloth, we would turn over one side of it an inch from the edge to make a sort of trough, pour in the gunpowder, carefully paste all the rest of it and fold it over and over, and then, when it begins to dry, double it up and tie it with string. we should then only have to add touch-paper, which, of course, we could make out of anything, and put into the end fold. we could break up a few of the cartridges, soak them in wetted powder, and then cut them up into small pieces and stick them into the ends of the crackers. i think that would do first-rate. i have made dozens of crackers, and feel sure that i could turn out a good lot of them now. the squibs will be easier; we should only have to paste one side of the strips and roll them up so as to form suitable cases. when these are dry we should put a thimbleful of powder into each, and then fill them up with powder and charcoal. in order to make sure of a loud bang we could undo a piece of rope and wind the strands round each case for an inch and a half from the bottom. of course, when we had ground down the burned wood we would mix it with powder and try one or two of the squibs, so as to find the proportions of charcoal to be used."

"you have evidently thought it all out well, and i think it does you no end of credit. i authorize you to begin the experiment at once. the first thing, of course, will be to get some wood and char it. i should think that you would require at least two pounds of that to two pounds of powder; but you had better only do a little at first—just enough to make an experiment. you know it will require ramming down well."

when dias, who was on watch, returned he found bertie at work burning pieces of wood and scraping off the charred surface. harry explained the plan to him. as he had frequently seen fireworks at lima, dias quickly grasped the idea.

"it is splendid, se?or; those things will frighten them far more than guns. they will think so many devils have got among them, and we will heighten the effect by discharging every piece that we can among them. in their confusion they will think it is the fireworks that are killing them. that would be necessary, for otherwise when they recovered from the panic and found that no one had been hurt, they might summon up courage to return."

at noon the next day bertie with assistance had four squibs and two crackers ready for trial. the squibs contained respectively one, two, three, and four parts of charcoal to one of powder.

"don't hold them in your hand while you are trying the experiment, bertie. lay them down on that stone one by one and touch them off with a burning brand from the fire, and take care that you have a good long one."

all, with the exception of josé who was on watch, gathered round. the first squib exploded with a bang, the second did the same, but with less violence, the third went off in an explosive spurt, the fourth burned as a squib should do, though a little fiercely, and gave a good bang at the end.

"they go off rather too rapidly, bertie," harry said; "we should want them to whiz about in a lively way as long as possible. i should put in five parts of that burned wood next time."

"i will try at once," bertie said. "i have got lots of cases made, and enough burned stuff to make eight or ten more."

the mixture was soon made and another case charged, bertie ramming down the mixture with a stick which he had cut to fit exactly, and a heavy stone as a hammer. this was done after each half-spoonful of the mixture was poured in. then he inserted a strip of his touch-paper.

"i will take this in my hand," he said, "there is no fear of its exploding. i want to throw it into the air and see how it burns there."

the touch-paper was lit, and when the mixture started burning bertie waved the squib high above his head and threw it into the air. it flew along some fifteen yards and then exploded.

"i don't think you can better that, bertie. but you might make the cases a bit stronger; it burned out a little too quickly. we shall probably not be able to get very close to them."

the cracker was equally satisfactory, except that they agreed that a somewhat larger charge of powder should be used to increase the noise of the explosion.

"now, bertie," harry said, "we will put all hands on to the business. donna maria shall make a good stock of paste, and cut the tick into strips for both widths. you shall make the cases for the squibs. dias and i will take charge of the manufacture of charcoal. that will be a long job, for as you have two pounds of gunpowder we shall want ten of this charred wood."

"not quite as much as that, harry, because we shall want the powder alone for the crackers and the bangs of the squibs, and also for making the touch-paper for all of them."

"well, we will say ten pounds, anyhow. we have a big stock of cartridges, and can spare a few of them for so good a purpose."

they were soon at work. by night the cases were all made and drying, and were left near the fire so as to be ready for filling in the morning.

dias then said: "josé will go down to-night, se?or. of course i shall go with him. we must find out, in the first place, how near the mouth of the ravine the savages are gathered, whether they keep any watch, and what force they have. it will be well not to make ourselves known to them until at least the greater part are gathered there. if we were only to scare a small party, the others, when they came down, would know nothing of the panic, and might take up the pursuit."

"i wish we had some means of driving them off the top of the hill, dias."

"i don't see how that can be done, se?or. but probably in another day or two they will all go down of their own accord. they must by this time have satisfied themselves that there is no getting at us from above, and that it would be too dangerous to attempt a descent here under the fire of our guns. they will be very likely, instead, to go down to-morrow or next day to hold a general council, and in that case they may decide either to risk climbing down at night, or to make a grand assault on the breast-work. or, if they cannot bring themselves to that, they may decide to leave half a dozen men to watch the entrance, while the rest scatter themselves over the forests. in that case the watchers would only have to go off and summon them when we started again. as they might well imagine that we should not find another position like this again, i expect that is what they will do. if there are a hundred of them, they will find it difficult to feed themselves long. certainly the men on the hills will get little to eat up there."

"well, dias, be sure you warn josé to be careful. they may be posting sentries at the mouth of the ravine, just as they are keeping them at this end."

"they may be, but i do not think it is likely; they will know that we could not abandon our animals, and that if we passed through they would have no difficulty in over-taking us, and would then have us at their mercy. the last thing they would want is to prevent us from leaving this position. they certainly would not fear an attack from us, knowing that there are but four of us and a woman. therefore, i think it probable that they will keep at some little distance from the entrance, so as to tempt us to come out."

"i hope it is so, dias. still, josé will have to be very careful."

"he will be careful, se?or. he knows his own life will depend upon his crawling along as noiselessly as a snake. if he is seen, of course he will come at all speed back to me; and, unless he is hit by a chance arrow, he will not run much risk, for by the time they are ready to shoot he will be out of sight on such dark nights as these, and in the shade of the mountains and trees. i shall be ready to send four barrels of buck-shot among them when they come up. that is sure to stop them long enough to allow us to get under the cover of your rifles before they can overtake us.

"i don't think that you need be at all uneasy about him, se?or. we will start in an hour's time, so that josé can get near them before they go to sleep. they will probably have a fire burning, but if not the only guide to their position will be the sound of their talking. he will strip before he leaves me, so that if they catch sight of him, they will suppose that he is one of themselves."

bertie now relieved josé, who came back and had a long talk with dias.

"we are ready now, se?or."

"here is my fowling-piece. it is already loaded with buck-shot. bertie has taken down his rifle and gun, and will give you the latter as you pass. i suppose josé will take no weapons?"

"only a long knife, se?or, that may be useful if he comes upon one of them suddenly."

at the barricade josé stripped, retaining only a pair of sandals. these were as noiseless as his bare feet, and would be needed, as in the dark he might tread upon a thorny creeper, or strike against a projecting rock.

"good-bye, josé!" harry said. "now, be careful. it would be a great grief to us if anything happened to you."

"i will be careful, se?or. the indians won't catch me, never fear."

harry and bertie both shook hands with him, and then he and dias stepped into the water, and, keeping close along by the wall of rock, started on their perilous expedition.

"i don't like it, bert," harry said as they lost sight of them. "it seems a cowardly thing to let that lad go into danger while we are doing nothing."

"that is just what i feel, harry. i would have volunteered willingly, but he will do it a great deal better than either you or i could."

"there is no doubt about that," harry agreed. "of course when he is out with the mules he often travels at night, and certainly both he and dias can see in the dark a good deal better than we can."

there was suddenly a slight movement behind them, and they turned sharply round. "it is i, se?or. i am anxious about dias, and i didn't like staying there by myself. i thought you would not mind if i came up and sat by you."

"certainly not," harry said. "sit down and make yourself comfortable. i do not think there is any fear for dias. he cannot be taken by surprise, for he will hear by their shouting if they discover josé, and you may be quite sure that he will bring them to a stand with the four shots he will fire among them as they come near, and so will get a good start. they might run faster than he can in the forest, but will scarcely be better able to make their way up the torrent."

when dias had been gone twenty minutes their conversation ceased, and they sat listening intently. in another ten minutes, which seemed an hour to them, harry said, "the savages can keep no watch at their end of the torrent, and josé must have got safely away."

very slowly the time passed.

"they must have been gone an hour," bertie said at last.

"quite that, i should think, bertie. at any rate, we may feel assured that all has gone well so far. for, though we might not hear the yells of the savages over the rustle and roar of the torrent, we should certainly hear gunshots."

another half-hour passed, and then to their relief they heard dias call out, "all is well!" some little distance down. in three or four minutes they could see the two figures approaching. "give me your guns, dias," harry said, "and then i will help you up the rocks. they might go off if you were to make a slip. now, while josé is putting on his clothes, tell me what he has found out."

"i have not heard much, se?or. as soon as he rejoined me we started off, and, coming up the torrent, we had not much chance of talking. he told me that there were many of them, and that they were camped at some little distance from the stream, just as i thought they would be."

"i will stay here, harry," bertie said. "you can hear the news and then come and tell me."

"very well. i will be back before long."

dias, his wife, and harry walked down towards the tent, and bertie chatted with josé while the latter was dressing.

"you must feel horribly cold, josé," he said.

"i am cold, now i think of it. i did not notice it while i was watching the savages. when i took to the water again i did feel it. maria will make me a cup of hot coffee, and then i shall be all right again. it was good fun to look at them, and know that they had no idea that i was so close. if i could have understood their language, i should have learned something worth telling. i felt inclined to scare them by giving a tremendous yell, and i know i could have got away all right. they were sitting round a big fire and would not have been able to see in the dark. i should have done it, only i thought dias would have blamed me for letting them know that one of us had come down the ca?on."

"he would have been angry, josé, and so would my brother, for they would certainly have set a watch afterwards, which would have spoilt all our plans. now run along, your teeth are chattering, and the sooner you get something warm and wrap yourself up in your blankets the better."

the fire had burnt low when the others returned, but an armful of sticks was thrown upon it at once. the kettle had been left in the embers at its edge by maria when she started, so that after it had hung in the blaze for two or three minutes it began to boil, and coffee was soon ready. at this point josé ran in, and after he had drunk a large mugful he told them what he had learned.

"when i left dias at the mouth of the ravine," he said, "everything seemed quiet. i walked along the edge of the stream for fifty yards, keeping my ears open, you may be sure, and i saw a light glow close under the rocks some distance on the other side of the river. i followed the stream down till i came to a place where there was a quiet pool, and there i swam across, then very carefully i made my way to where i could see the light. it was quite three hundred yards from the river. as i got near i could hear talking; i crawled along like a cat, and took good care not to disturb a leaf, or to put a hand or a knee upon a dried stick, for i could not tell whether they had anyone on watch near the fire. i perceived no one, and at last came to a point where i could see the flame. it was in an opening running a hundred feet into the mountains, and perhaps forty feet across at the mouth.

"in this were sixty or seventy savages sitting or standing round a fire, which had evidently been made there so that anyone coming down to the mouth of the ravine should not see it. the fire was not a very large one, and a good many of the men were gathered outside the little hollow. some of them were talking loudly, and it seemed to me that they were quarrelling over something. sometimes they pointed up to the top of the hills, sometimes towards the mouth of our ravine. i would have got close if i had understood their language. presently i saw some of them lying down, so that i could see that the quarrel, whatever it was about, was coming to an end, and that they were going to lie down for the night. as i could learn nothing further i crawled away and went down to the place where i had swum the river before, and then crept quietly up to dias, who was on the look-out; for although i had seen no one as i had passed before, there might still have been some of them on the watch."

"you have done very well, josé," harry said. "we have learned two things. first, that they are not keeping watch at the mouth of the ravine, either because they feel sure that we will not try to escape, or because they wish us to leave and are giving us the opportunity of doing so. in the second place, you have learned what force they have got down there, their exact position, and the fact that they were evidently arguing how they had best attack us. well, from what you say there is every chance that we shall be able to come upon them without being noticed till we are close enough to throw our fireworks among them. really the only thing for us to learn is whether many of them are still at the top of the hill."

"i hardly think there can be many; only a few have shown themselves to-day. they must know very well that we would not venture to climb up during the day, and that it would be next to impossible for us to do so in the dark, even if we made up our minds to abandon the animals and all our stores."

"well, i should say, dias, there is no reason why we should put the matter off. it will not take us long to load all the squibs to-morrow. my opinion is that at dusk we had better saddle the mules and pack everything on them in readiness for a start; then at ten o'clock we can go down and attack the savages. the best moment for doing so will be when they are just lying down. when we have sent them flying we will come up the torrent again, and start with the mules as soon as it is daylight. it would be next to impossible to get them down in the dark, as they might very easily break their legs, or by rubbing against the wall shift their packs and tumble them into the water."

"it would be a pity to waste time, se?or. i will get some torches made to-morrow. some of the trees have resin, and by melting this i can make torches that would do very well. by their aid we could get the mules down without waiting for daylight. as they have already come up the torrent, they will have less fear in going down, for the stream will help them instead of keeping them back. i will go first with josé and his mule; she is as steady as a rock, and where she goes the others will follow; and with five torches along the line they will be able to see well enough."

"four torches, dias. your wife rode coming up, and she had better ride going down."

"she can hold a torch as she sits; it does not matter to us if we get wet to the waist, but it would be very uncomfortable for her. we shall have to put the largest burdens on to the mules. one of the riding mules could carry the two llamas, or if you think that that is too much, we can tie each across a separate mule. they were more trouble coming up than all the mules put together. we had pretty nearly to carry them through the deep places, though at other points they leapt from rock to rock cleverly enough."

"i am not going to be left behind if you are going to the fight, se?or," donna maria said, "if you will give me one of your pistols."

"we could manage that, i should think," harry said. "we can put you on one of the steadiest mules when we first go down, and with one at each side of you we can manage it very well. josé must go on a hundred yards ahead to see whether any of the savages are on the watch at their end, and if so, you must wait till we have cleared them out. you see, we shall have no hesitation in shooting any of them if necessary, and though that would bring the rest of them down on us, yet when our squibs and crackers begin to fly among them, you may be sure they won't face us for an instant."

dias grumbled that his wife had better stay where she was till they went back for the mules; but harry said: "i do think, dias, that she had better go with us. it would be cruel to leave her now that we are going into a fight—leave her all alone to tremble for our lives, with a knowledge that if things should go wrong with us the savages will soon be up here."

"well, se?or, if you think so, there is no more to be said."

"i am not going to be made a trouble of," maria said. "i shall go down on foot like the rest of you. i will take some other clothes with me, so that when you all come back for the mules i can change into them."

"perhaps that would be the best plan," harry agreed. "now i will go back and take bertie's place. it is my turn to be on watch, and he will be wanting to hear the news."

"well, harry, is it all right?" bertie asked as he heard his brother coming up to him.

"it couldn't be better! there are sixty or seventy of them in a sort of little ravine three hundred yards away, on the left-hand side of the river. they don't seem to be keeping guard at all, and if they are not more careful to-morrow night we shall take them completely by surprise. we are going to saddle all the mules directly it gets too dark for any of the fellows on the hills to see us, then we must set to work and pull down enough of the barricade here to allow them to pass. we ourselves, when we go down, will cross at that shallow place above here, and go down the river at that side, otherwise we sha'n't be able to cross it except at some distance beyond the other end of the torrent. of course the mules must go down this side, as we shall want to turn to the right when we get off. we shall make our attack about ten o'clock."

bertie went off, and three hours later dias relieved harry. as soon as it was light the next morning bertie and josé set to work to fill the cases—there were a hundred squibs and fifty large crackers.

donna maria after breakfast went out and returned with a number of flexible sticks of about half an inch in diameter; these she carried into her tent, where she shut herself up for the forenoon. when, at one o'clock, she came out with the result of her work, it resembled a chair without legs and with a back about a foot wide and three feet high.

"what in the world have you got there, donna maria?" bertie asked.

"don't you know?"

"no, i have never seen a thing like it before."

"this is the thing the porters use for carrying weights, and sometimes people, over the cordilleras. you see that strap near the top goes round the man's forehead, and when there is a weight in the chair these other straps pass over his shoulders and under his arms, and then round whatever is on the seat."

"but what is going to be on the seat?"

"i am," she laughed. "dias is so overbearing. it had all been arranged nicely, as you know; and then when he spoke to me afterwards he said, 'the first thing to-morrow morning, maria, you will set to work to make a porter's chair, and i shall carry you down the stream. no words about it, but do as you are told.' generally dias lets me have my own way, se?or, but when he talks like that, i know that it is useless to argue with him. and perhaps it is best after all, for, as he said to me afterwards, it is a nasty place for men to get along, but for a woman, with her petticoats dragging and trailing round her, it would be almost impossible for her to keep her footing."

"well, i thought the same thing myself when we were talking about it yesterday," bertie said. "of course i did not say anything, but i am sure dias is right. i found it very hard work to keep my footing, and i really don't believe that i could have done it if i had been dressed as a woman. and dias can carry you like that?"

"carry me, se?or! he could carry three times that weight. he has cut himself a staff seven or eight feet long this morning to steady himself, but i don't think there was any need for it. why, it is a common thing for people to be carried over the cordilleras so, and dias is stronger a great deal than many of the men who do it. as he said, if i had been going through on foot you would all have been bothering about me. and it is not as if two people could go abreast, and one help the other. there is often only room between the rocks for one to pass through, and it is just there where the rush of the water is strongest."