6 the invisible chalk.

after a few weeks alicia got restless. it's time we livened things up a bit!" she said to betty. i knowwe're second-formers now and all that—but there's no reason why we shouldn't have a bit of fun.

sally's such a bore-never a joke, never a trick!”

"what shall we do?" said betty, her wicked dark eyes gleaming. i’ve got some invisible chalk. haveyou got anything?"

"invisible chalk! yon never told met" said alicia, her face brightening. "what is it? show me!”

i’ve got it in my locker, in a box," said betty. "the common-room will be empty now. come alongand m show you. it’s queer stuff.”

the two girls went to their common-room. betty opened her locker and took out a tin box. inside,wrapped carefully in paper, was a thick slab of curious pink chalk.

"it doesn't look invisible!" said alicia. "what does it do?""well, if you rub it on to a chair, it can't possibly be seen." said betty. "and whoever sits down on itmakes it warm and it leaves a bright pink patch on a dress or skirt.""i see," said alicia. "golly—we could rub it on the mistress's chair in our form-room—whenmam'zelle rougier is coming perhaps."

1 know! let’s rub it on to mr. young's chair, when he comes to take singing!" said betty. "on hispiano stool! then he’ll sit down hard on it when he playsaccompaniment for our songs—and when he getsup and turns round to write on the blackboard—golly, what a scream!”

alicia laughed loudly. "it would be better to play it on mr. young than on nosey or mam'zelle—hewon't suspect a thing—and the first form will have a share in the joke too, because they take singingwith us!"

alicia cheered up considerably after this. she and betty tried out the invisible chalk very carefully,and it was a great success.

betty took a wooden-bottomed chair and rubbed the curious pink chalk all over it. "look,” she said,"it doesn't show at all, alicia. can you see anything of it?” alicia looked carefully at the chair,tipping it this way and that "it's perfect,” she said. "not a thing to be seen! funny how you can rub iton and it seems to disappear, betty. it really is invisible. now. you sit down on it and let me see whathappens."

betty sat down, and remained there for a minute or two. the chalk would not work unless it wasslightly warmed. as betty was sitting solemnly there with alicia watching her. gwendoline poppedher head in to look for daphne. she was astonished to see betty sitting solemnly by herself on achair, with alicia a little way off.

"what are you doing?” she asked curiously. "what's happening?”

"nothing," said alicia. "buzz off! daphne's not here.""but what are you doing?" persisted gwendoline, suspecting something, though she didn't know what"why is betty sitting on that uncomfortable chair in the middle of the room like that?""alicia! nosey wants you!” suddenly cried a voice, and jean's head came round the door. "hurry!

she's in a stew about something. your maths paper, i should think.""blow!" said alicia, and shot off. "be back in a minute, betty," she said, and ran down the passage.

jean looked with interest at betty sitting all alone in the middle of the common-room.

“tired?" she asked. betty scowled. she felt foolish. she wanted to hurl a book at gwendoline's sillygolden head, but she didn’t dare to get up in case she had a nice chalky pattern on her back. shedidn't want to let anyone else into the trick at the moment.

"paralysed or something, poor thing," said gwendoline. "can't get up. or perhaps it's rheumatism!"to betty's great relief gwendoline became tired of teasing her and went out to find daphne. jeangave a grin and left too. betty got up and looked round at herself. she gave a chuckle of delight. shehad a brilliant pink pattern on the skirt of her tunic. how extraordinary that the invisible chalk shouldact like that when it was warmed up!

alicia came flying in. "does it work?" she cried, and giggled when betty swung round and showedher the bright pink marks. "golly, it's fine i well try it on old mr. young tomorrow!""shall we tell anyone?" asked betty.

"not a soul," said alicia. "someone's sure to give it away by giggling if we do. no—we'll let dearmr. young spring this surprise himself on an astonished audience!"neither betty nor alicia did much prep that night potty, who was taking prep, looked with suspicionat the two plotters and wondered what was up. it was obvious that their thoughts were pleasantly andhumorously engaged far elsewhere.

potty knew the signs. she warned miss parker. "those two in your form, alicia and betty, are up tosomething. miss parker. look out tomorrow. you’llhave an unaccountable smell, or a curious noise, or an orgy of book-dropping or something.""thanks." said miss parker grimly. i’ll watch out."but she could see nothing out of the way in her first lesson, or in her second one either. the girlsworked much as usual. only alicia and betty seemed restless. but then they often were, especiallyalicia, whose quick mind often chafed at the slower rate of the others.

the lesson before break was singing. just before the second lesson was finished betty put up herhand, "please, miss parker, it's my turn to get things ready for mr. young in the singing-room. may igo?"

miss parker glanced at the clock. "yes. you have about four minutes."betty flashed a quick grin at alicia and went demurely to the door. once outside she raced down thecorridor and made her way to the singing-room. no one was there. mr. young was always a minuteor two late, thank goodness!

betty flew to the piano stool. it was the round leather-topped kind, that could be screwed round andround. betty took out her piece of pink chalk and rubbed it vigorously all over the top of the roundstool.

she was sure there was not a single spot unchalked, though, of course, she could not see anything ofwhat she had done at all. it certainly was invisible chalk!

then she quickly sent the stool spinning round till' it was too low for mr. young. if ever it was toolow or too high he had a little habit of sitting on the stool and going round and round with it till it hadreached the height he liked. if only he did that today it would give the chalk a wonderful chance ofgetting properly on to him!

betty stacked the music ready and cleaned the blackboard. then there came the sound of feet and thefirst

form marched into the room under the sharp eye of miss potts.

then came the second form. alicia's eyes were bright. betty grinned at her and winked. then shewent to hold the door for the two mistresses to go out and for mr. young to come in.

in he trotted, a dapper little man in a well-brushed black suit and a too-high collar. he smoothed hispointed moustache and bowed politely to the girls.

"good morning, young ladies."

"good morning, mr. young," they chorused, and rustled their song-sheets. the lesson began. mr.

young took some blackboard drill for five minutes, explaining various notes and signs. then he wentto the piano.

betty nudged alicia and held her breath. but, most annoyingly, mr. young did not sit down. hestruck a few notes with one hand, standing facing the girls as he did so, his baton raised.

"exercises, please," he said. "i wish to see your mouths well open, and to hear the sound comingfrom the back of the throat."

mr. young set great store on the "back of the throat". it was always coming into everything,exercises, songs and sight-reading. "back of the throat" was his one unfailing motto.

now he stood, instead of sitting, and conducted the exercises. alicia was in agonies ofdisappointment. suppose he didn't sit down at all? probably the next person then, to sit down wouldbe the accompanist of the mistress who taught dancing—and she always wore a brightly colouredfrock so that the chalk wouldn't show at all. what a waste!

but mr. young did sit down eventually, of course. he had a new song to teach to the girls, and, asalways, he wanted to play the whole thing through two or three"the chalk ought to be working now!"

times before he taught it, so that the girls could catch the hit and swing and tune of itso down he sat. aha! that stool was once more too low! mr. young twirled himself vigorouslyround on it till it was the right height. the girls giggled. mr. young could never realize how funny hewas, twirling round lightly on that little stool.

"now i will play you your new song," said mr. young. "you may sit to listen to it. you will hearwhen the chorus comes, for i will sing it to you."off he started, tumty-tum-ti-tam, his hands flying up and down, and then his voice booming out at thechorus. alicia and betty winked at one another. the chalk ought to be working now tthree times mr. young played the song and then he got up. "did you like it?" he asked, and the girlschorused loudly. "oh, yes, mr. young!”

mr. young turned towards the blackboard and picked up a piece of white chalk. at once the girls sawthat he was smeared with the brightest pink at the back! they stared in delight.

"look at mr. young! what's he rubbed against? oh, do look!"soon the class was in a state of giggle and mr. young glared round.

"silence, please! what behaviour is this today?" there was a momentary silence, but as soon as theunfortunate singing-master turned back to the board again more giggles broke out then irene gaveone of her terrific explosions.

mr. young flung the chalk down on the floor. he looked as if he was about to stamp on it andprobably he would have done so if the door hadn't suddenly opened, and miss grayling appeared.

she had someone with her.

"oh, excuse me for interrupting your class, mr. young," she said. "but could you just have a wordwith mr. lemming about the piano here?"

mr. young had to swallow his annoyance and explain what was wrong with the piano. in doing so heturned his back to miss grayling who eyed this patch of brilliant pink with the utmost astonishment.

the girls were as quiet as mice now, and alicia and betty felt distinctly anxious.

miss grayling turned to sally, the head of the second form. "will you go to the hall and fetch theclothes brush there?" she said. "poor mr. young has brushed against something."sally flew off and fetched the brush. mr. young was surprised to hear miss grayling's remark. helooked over his shoulder trying to see himself.

"is it paint?" he asked in alarm. "i do hope not! oh—only chalk! how in the world did it get there?""oy!"

soon the offending pink chalk had been vigorously brushed away by mr. lemming, who thenproceeded to sit down on the piano stool himself to try out some of the bass notes, which had gonewrong. alicia and betty watched breathlessly. most of the girls, guessing that some trick was beingplayed, watched eagerly too.

they were well rewarded when mr. lemming rose from the stool. he was wearing a long blackovercoat and on it was a wonderful pattern of bright pink. mr. young stared at it in amazement"ah, you have it tool" he cried. "see, miss grayling. mr. lemming has brushed up against somethingalso. i will soon put him right."

in spite of being under miss grayling's eye the girls began to giggle. miss grayling looked verypuzzled.

"your coat was quite all right when we came along here," she said to mr. lemming. i am sure ishould have noticed it if you had brushed against anything so violently pink as this. in any case thereis no wall as pink as this chalk! whatever can have happened?"she walked to the stool and looked at it very closely. alicia and betty hardly dared to breathe. butthe invisible chalk lived up to its name and miss grayling did not see a sign of it. it did not occur toher to sit down and see if the same thing happened to her. still feeling puzzled she took mr.

lemming out of the room, and the lesson proceeded again.

not until the end of it did poor mr. young sit down on that stool again. when he got up, behold! hewas as pretty a sight as before, and the girls stuffed their hankies into their mouths trying not toexplode with mirth. mr. young noticed nothing this time. he walked pompously to the door and gavethe girls the quick little bow he always kept for them.

"good morning, young ladies!" and out he went, showing his patch of brilliant colour. as he wentthe bell for break rang, and the girls tore into the court, longing to give way to their pent-up laughter.

"alicia! you had something to do with it! what was it?""oh, it was marvellous! when be turned round to the blackboard i thought i should die!”

"betty! darell! was it your trick? how did you do it? i looked at the stool and there wasn't a thing tobe seen!"

"that reminds me,” said betty to alicia with a grin. "i must get a wet cloth and rub it over the stool"she disappeared, and the girls surged round alicia, begging her to tell them the secretmeanwhile mr. young was walking down one of die long corridors, quite unaware of his beautifuldecoration. mam'zelle dopoot happened to come out of a room just behind him, and stareddisbelievingly at the extraordinary sight. she raced after him.

"monsieur young! ha, monsieur young!"

mr. young was scared of both mam'zelles. he hastened his steps. mam'zelle ran more quickly.

"monsieur, monsieur, attendez, je vous prie! wait, wait. you cannot go out like that! it is terrible!”

mr. young swung round, annoyed. "what is it? what's terrible?""this! this!" said mam'zelle. and tapped him smartly on the chalk, a cloud of it flew off at once. mr.

young was horrified at being tapped so familiarly by mam'zelle and amazed at the cloud of chalk thatsew from his person. he wriggled himself round to try and see it, remembering what mr. lemming'scoat had been like.

"i will attend to you," said mam'zelle, out of the kindness of her heart,, and caught hold of his arm.

she hurried him to a hall-stand, took up a brush there, and with extremely vigorous strokes sheremoved the chalk from his clothes.

he was angry and not at all grateful. 'twice it has happened this morning," he said angrily tomam'zelle and actually shook his fist in her face as if she was the culprit. she backed away, alarmed.

mr. young snatched up his hat and went off. muttering to himself.

"he is not polite, that man," said mam'zelle to herself. "i do him a kindness, and he puts his fist intomy face. i will never speak to him again."

the only girl who had seen this episode in the hall was darrell, and she hurried to the others with thetitbit "i was going past the end of the hall and i saw mam'zelle banging at mr. young for all she wasworth

with the clothes brush," she panted "he was so angry! oh, do let’s do it again. alicia. it's a gorgeoustrick!"

it is always a mistake to play the same trick twice running, and alicia knew it but she could not resistthe temptation to try it on mam'zelle dupont

"shall we?" she asked betty, and betty nodded in glee. the girls crowded round to see the queerinvisible chalk. they chuckled and laughed when they thought of the singing-lesson, and they let thefirst-formers into the secret too.

altogether the trick cheered up everyone considerably, and the thought mat they would play it oncemore gave them something to look forward to.

"who can rub it on the mistress's chair before the french lesson this afternoon?” demanded betty.

"alicia and i can't. we've no chance of being in the room. who is room monitor?""i am." said darrell. i’ll do it! give me the chalk! what do you do? just rub it over the chair?"ten minutes before afternoon school darrell slipped into the second-form classroom. it was her jobthat week to tidy the bookshelves, clean the blackboard and see that the chalk was handy and theduster there.

it took her only a minute to do these things. then she went to the chair that stood behind the desk andtook the chalk from her pocket. she was about to rub it over the seat of the chair when a mischievousidea struck her.

couldn't she write something short so that a word would appear on mam'zelle's skirt and sendeveryone into fits? it would have to be a short word.

"ill write 'oy’ " said darrell to herself, in glee. "i’ll have to write it backwards, so that it will comeoff on mam'zelle the right way round."

so, very painstakingly she rubbed the chalk on the seat of the chair in the form of the two letters oand y. oy! fancy going about with that written on you! how all the girls would yell!

the bell went for lessons. darrell slipped the chalk into her pocket and went to her place. she giggledwhen the rest of the form came in.

"did you do it? did you have time?" whispered the girls. darrell nodded. then in came mam'zelle,appearing to be in quite a good temper, and the door was shut.

mam'zelle sat down at once. she had very tiny feet and did not like standing. the girls watchedeagerly. when would she stand up? darrell could hardly wait for her to turn her back to the class.

what would they say when they saw what she had written on the chair!

jean was called to the blackboard to write something. "do it all wrong!" hissed darrell. thenmam'zelle will get up to correct it."

so, much to mam'zelle's surprise, die usually careful jean made ridiculous mistakes in the frenchwords she wrote down, and appeared to be quite unable to put them right, despite mam'zelle'sexasperated instructions. at last thoroughly annoyed, she dismissed jean to her seat, and got up to putthe mistakes right herself.

the class saw her back view at once, and gasped. written across her tight-fitting skirt in bright pinkletters was the word "oy!" even darrell was surprised to see it so clearly, and suddenly felt veryuncomfortable. it was one thing to make a patch of pink appear on somebody's clothes—it couldeasily be explained away—but how could the word "oy" be explained? it was quite impossible.

the class gaped at mam'zelle's back view. they were absolutely taken aback. they didn't knowwhether to giggle or to be alarmed

"darrell! you idiot! i suppose she goes walking up the corridor in front of all the other mistresseswith that written on her skirt!" hissed alicia. "really, you might have more sense.”

the thought of me other mistresses seeing mam’zelle's "oy!" really alarmed the form. miss parkerwould certainly not approve. she would consider it most disrespectful.

but how to get it off? that dreadful pink "oy” flashed back and forth as mam'zelle wrote on theboard, turned to the class to explain, and wrote again.

i’ll tell mam'zelle she's got some dust or something on her skirt and i’ll brush it off.” promiseddarrell, in a whisper. "at the end of the lesson."but she had no chance to, for mam'zelle walked off in a hurry, remembering that she was late for thefirst form, next door. and the first-formers had the surprise of their lives when they saw mam’zelle'spink "oy" flashing at mem every other minute!

they couldn't keep back their giggles and mam'zelle grew more and more furious. "what is there sofunny about me this afternoon?'' she demanded. "is my hair untidy? is my face black? are my shoesnot a pair?"

"no, mam'zelle," said the first form, almost helpless with trying to stop their laughter.

"i am not funny and i do not feel fumy," said mam'zelle, severely. "but i shall soon do some funnythings. ah, yes! i shall soon say 'one hundred lines of french poetry from you, please, and from youand you! aha! i shall soon be very funny!

with that she swung round to the blackboard and the “oy!" flashed again. the first form clutchedone another in agonies of suppressed laughter.

but all the same they had the sense to grab mam'zelle before she went out of die room. "well have toget that off her before she goes," said hilda. "or else the second-formers will get into awful trouble. iexpect they meant to brush it off somehow and didn't have the chance.”

so, before mam’zelle left the first-form room, hilda politely offered to brush down her skirt, as it wasall dusty with chalk.

"tiens!" said mam'zelle, looking down at it this blackboard chalk! it is not good for dresses. thankyou, hilda, vous ties gentile! you are kind. she stood like a lamb whilst hilda assiduously brushedher skirt back and front, and got rid of the pink "oy" then she walked out of the room. the second-formers, who had finished their lesson, were watching for her, hoping to brush her down themselvesbefore she went off to the little room she shared with miss potts.

with great relief they saw that mam'zelle's skirt was now spotless. they went back into their form-room and sank down into their chairs.

thank goodness!" said alicia. "we might have got into a first-class row over mat potty or noseywould certainly have reported it if they'd seen that 'oy’ you know how annoyed the mistresses get ifthey think we've been really disrespectful, darrell. you were an idiot! i suppose salty put you up toit. fine head of form she is!"

"shut up!" said darrell, annoyed with herself and everyone else too. "sally had nothing to do with it.

i just didn't think, that's all.”