the flat mountain looked much nearer in the clear light of the morning sun, but dorothy and ozma knew there was a long tramp before them, even yet. they finished dressing only to find a warm, delicious breakfast awaiting them, and having eaten they left the tent and started toward the mountain which was their first goal. after going a little way dorothy looked back and found that the fairy tent had entirely disappeared. she was not surprised, for she knew this would happen.

"can't your magic give us a horse an' wagon, or an automobile?" inquired dorothy.

"no, dear; i'm sorry that such magic is beyond my power," confessed her fairy friend.

"perhaps glinda could," said dorothy thoughtfully.

"glinda has a stork chariot that carries her through the air," said ozma, "but even our great sorceress cannot conjure up other modes of travel. don't forget what i told you last night, that no one is powerful enough to do everything."

"well, i s'pose i ought to know that, having lived so long in the land of oz," replied dorothy; "but i can't do any magic at all, an' so i can't figure out e'zactly how you an' glinda an' the wizard do it."

"don't try," laughed ozma. "but you have at least one magical art, dorothy: you know the trick of winning all hearts."

"no, i don't," said dorothy earnestly. "if i really can do it, ozma, i am sure i don't know how i do it."

it took them a good two hours to reach the foot of the round, flat mountain, and then they found the sides so steep that they were like the wall of a house.

"even my purple kitten couldn't climb 'em," remarked dorothy, gazing upward.

"but there is some way for the flatheads to get down and up again," declared ozma; "otherwise they couldn't make war with the skeezers, or even meet them and quarrel with them."

"that's so, ozma. let's walk around a ways; perhaps we'll find a ladder or something."

they walked quite a distance, for it was a big mountain, and as they circled around it and came to the side that faced the palm trees, they suddenly discovered an entrance way cut out of the rock wall. this entrance was arched overhead and not very deep because it merely led to a short flight of stone stairs.

"oh, we've found a way to the top at last," announced ozma, and the two girls turned and walked straight toward the entrance. suddenly they bumped against something and stood still, unable to proceed farther.

"dear me!" exclaimed dorothy, rubbing her nose, which had struck something hard, although she could not see what it was; "this isn't as easy as it looks. what has stopped us, ozma? is it magic of some sort?"

ozma was feeling around, her bands outstretched before her.

"yes, dear, it is magic," she replied. "the flatheads had to have a way from their mountain top from the plain below, but to prevent enemies from rushing up the stairs to conquer them, they have built, at a small distance before the entrance a wall of solid stone, the stones being held in place by cement, and then they made the wall invisible."

"i wonder why they did that?" mused dorothy. "a wall would keep folks out anyhow, whether it could be seen or not, so there wasn't any use making it invisible. seems to me it would have been better to have left it solid, for then no one would have seen the entrance behind it. now anybody can see the entrance, as we did. and prob'bly anybody that tries to go up the stairs gets bumped, as we did."

ozma made no reply at once. her face was grave and thoughtful.

"i think i know the reason for making the wall invisible," she said after a while. "the flatheads use the stairs for coming down and going up. if there was a solid stone wall to keep them from reaching the plain they would themselves be imprisoned by the wall. so they had to leave some place to get around the wall, and, if the wall was visible, all strangers or enemies would find the place to go around it and then the wall would be useless. so the flatheads cunningly made their wall invisible, believing that everyone who saw the entrance to the mountain would walk straight toward it, as we did, and find it impossible to go any farther. i suppose the wall is really high and thick, and can't be broken through, so those who find it in their way are obliged to go away again."

"well," said dorothy, "if there's a way around the wall, where is it?"

"we must find it," returned ozma, and began feeling her way along the wall. dorothy followed and began to get discouraged when ozma had walked nearly a quarter of a mile away from the entrance. but now the invisible wall curved in toward the side of the mountain and suddenly ended, leaving just space enough between the wall and the mountain for an ordinary person to pass through.

the girls went in, single file, and ozma explained that they were now behind the barrier and could go back to the entrance. they met no further obstructions.

"most people, ozma, wouldn't have figured this thing out the way you did," remarked dorothy. "if i'd been alone the invisible wall surely would have stumped me."

reaching the entrance they began to mount the stone stairs. they went up ten stairs and then down five stairs, following a passage cut from the rock. the stairs were just wide enough for the two girls to walk abreast, arm in arm. at the bottom of the five stairs the passage turned to the right, and they ascended ten more stairs, only to find at the top of the flight five stairs leading straight down again. again the passage turned abruptly, this time to the left, and ten more stairs led upward.

the passage was now quite dark, for they were in the heart of the mountain and all daylight had been shut out by the turns of the passage. however, ozma drew her silver wand from her bosom and the great jewel at its end gave out a lustrous, green-tinted light which lighted the place well enough for them to see their way plainly.

ten steps up, five steps down, and a turn, this way or that. that was the program, and dorothy figured that they were only gaining five stairs upward each trip that they made.

"those flatheads must be funny people," she said to ozma. "they don't seem to do anything in a bold straightforward manner. in making this passage they forced everyone to walk three times as far as is necessary. and of course this trip is just as tiresome to the flatheads as it is to other folks."

"that is true," answered ozma; "yet it is a clever arrangement to prevent their being surprised by intruders. every time we reach the tenth step of a flight, the pressure of our feet on the stone makes a bell ring on top of the mountain, to warn the flatheads of our coming."

"how do you know that?" demanded dorothy, astonished.

"i've heard the bell ever since we started," ozma told her. "you could not hear it, i know, but when i am holding my wand in my hand i can hear sounds a great distance off."

"do you hear anything on top of the mountain 'cept the bell?" inquired dorothy.

"yes. the people are calling to one another in alarm and many footsteps are approaching the place where we will reach the flat top of the mountain."

this made dorothy feel somewhat anxious. "i'd thought we were going to visit just common, ordinary people," she remarked, "but they're pretty clever, it seems, and they know some kinds of magic, too. they may be dangerous, ozma. p'raps we'd better stayed at home."

finally the upstairs-and-downstairs passage seemed coming to an end, for daylight again appeared ahead of the two girls and ozma replaced her wand in the bosom of her gown. the last ten steps brought them to the surface, where they found themselves surrounded by such a throng of queer people that for a time they halted, speechless, and stared into the faces that confronted them.

dorothy knew at once why these mountain people were called flatheads. their heads were really flat on top, as if they had been cut off just above the eyes and ears. also the heads were bald, with no hair on top at all, and the ears were big and stuck straight out, and the noses were small and stubby, while the mouths of the flatheads were well shaped and not unusual. their eyes were perhaps their best feature, being large and bright and a deep violet in color.

the costumes of the flatheads were all made of metals dug from their mountain. small gold, silver, tin and iron discs, about the size of pennies, and very thin, were cleverly wired together and made to form knee trousers and jackets for the men and skirts and waists for the women. the colored metals were skillfully mixed to form stripes and checks of various sorts, so that the costumes were quite gorgeous and reminded dorothy of pictures she had seen of knights of old clothed armor.

aside from their flat heads, these people were not really bad looking. the men were armed with bows and arrows and had small axes of steel stuck in their metal belts. they wore no hats nor ornaments.