PHYSICAL LABORATORY M ANUAL FOR SECONDARY SCH OOL S : R EVISE D E DI TI ON F D A . L . M C HAR E A A M . S S , H E A D OF TH E D E P A R T M E NT OF P H Y SICS D E TR OI T C E NTR A L H IG H SC H OOL NEW YORK CINCINNATI CH ICAGO A M E R I C A N B O O K C O M P A N Y COPYR IGH T , 1909 , B Y CH ARLES F . ADAMS. ’ ENTE R E AT STAT IONE R S H AL L LO NDON . D , AD AH P H Y B I A N S S LA . PREFACE S INCE the first edition of this book was published the physical laboratory has become the rule rather than the I i n w exception in the schools . t s o possible to b uy well m ade apparatus suitable f or the l aboratory of the second ar s at r as na r s so a at a s ab u y chool e o ble p ice , th t co t of o t one hun dred dollars an equipmen t can be procured by which a good complete laboratory course can be estab h T r a r m r or s m ar lis ed . eache s lso a e o e le s fa ili with the m d r r r F gene ral etho s of labo ato y p ocedure . or thes e reasons much of the matter in the former edition in re ard s rm and m a n a ara us ha g to the ize , fo , the ki g of pp t s b n m r m s . In a d man u n ee o itted f o thi f ct, the e ds po the time an d energy of the scie nce teacher a re so heavy that it is believed he can spend his time to bette r advantage in r d n an in m a n r Th othe irectio s th ki g appa atus . e school a utho rities should furnish the apparatus an d a suitable place f or storing it ; the teacher should see th at it is well a n ar an and ut awa in d rd r a t ke c e of, kept cle , p y goo o e s h d u n soon as he as fi nishe si g it . Although laboratory work in our schools has been r a x n d in as f ew ars r su s a v in g e tly e te de the l t ye , the e lt h e n m any cases been disappoi ting . It has been said that w r is n r n r s n nor ns ru v and the o k eithe i te e ti g i t cti e, it is thought that the m ain cause of this is the se verely m quan titative character of the exe rcises . It ay be that the quan titati ve aspect of the wo rk has received too m uch and ua a v v r uan emphasis the q lit ti e too little . E e y q tita 3 6 7 3 1 5 7 4 PREFACE v x r s h w v r has its ua a v a u r w ti e e e ci e , o e e , q lit ti e fe t e hich s ud n s u d be br u a r a and und rs an the t e t ho l o ght to pp eci te e t d, not th rough the quan titati ve work but as a prelimi nary to The au r is n n a t r ub has it . tho of the opi io th t the o le ar s n not aus x r s s are uan a v i e chiefly bec e the e e ci e q tit ti e, b ut because of the nature of som e of the e xperimen ts m nd ara r r the selves a the ch cte of the appa atus employed . Of w a ss n r s f or xam av ra h t po ible i te e t, e ple, to the e ge r or f or a m a r is an x r m n in r a n gi l , boy th t tte , e pe i e t b e ki g wire ? Or how is it possible to inspire respect f or the ub and n r s in w n a ara us and th s ject i te e t it, he the pp t e methods used are such that the teacher m ust apologize f or the results After twen ty years of e xperience in the physical labora r w ar ass s au r r s n s s x r s to y ith l ge cl e the tho p e e t the e e e ci es, which have been thoroughly tested in his own classes and in r s s w a firm a a ur can othe chool , ith belief th t co se be selected from them which will be both instructive an d T i nterestin g to the pupil . he methods and apparatus s r b d W v d r su s in ands u de c i e ill gi e goo e lt the h of p pils . The n umber of exercises is sufficiently large to allow n r u The m h co side able latit de of choice . s all school wit a limited equipment or the l arge school with ab undance of m eans can fi n d suitable m aterial f or a laboratory course of r A f e x rc ar n r u one yea . w e e ises e give which a e s ited f or a little more advanced work which some may wish to Th n um r x rc rm r give . e be of e e ises also pe its some va ia tion of the work from year to year and gi ves room f or development in the sm all school as its eq uipmen t in r c eases . If a r d s r s n um r uan a v oh the te che e i e , the be of q tit ti e servations in m any e xperime nts m ay be reduced to a m i nimum and the q ualitati ve feature of the work em A u n n r u phasized . ltho gh the book co tai s seve al q ali PR EFACE 5 ’ ta tive x r s s is au r s firm n n at e e ci e , it the tho co victio th the place f or the purely illustrati ve experimen t is in the ur r m ra r an in h lect e oo the th t e laboratory . ’ This m anual is inten ded as a companion book f or Adams s P s s f or ndar s and numb r in ar n hy ic Seco y School , the e s p e theses in the various exe rcises refer to paragraphs in that bo . It m a w v r be us d s ara or w an ok y, ho e e , e ep tely, ith y other text . CONTENTS CHAPTE R I SIM PL E M E A SU R E M E NTS E XER CISE P AGE Th r 1 . e M ete Stick 2 . The Diagon al Scale Th 3 . e Vern ier Th m 4 . e M icro eter Screw Th 5 . e Beam Balance T 6 . he Jolly Balance r n 7 . Graphic Rep esentatio of Results r r 8 . Density of a Rectangula P ism Sign ificant an d Doubtful Figures D t f n r C Den si y o a Cyli de f r 10. Density o a Sphe e CHAPTER II M E C H A NI C S OF SOL I D S c l r te M oti n 11 . Uniformly A ce e a d o m t n f ncurr n F r 12 . C o pos i io o Co i g o ces e orce 13 . Parall l F s l 14 . The Pendu um . T e n m Len t of Are 15 h Pe dulu . g h en f F r e 16. M om t o a o c I n 17 . The n clined Pla e E t t 18. las ici y CHAPTER III M E C H A N ICS OF FL U I DS D wnw r ressure in L u s 19 . o a d P iq id t r re s ure i n L u s 20. La e al P s iq id CONTENTS E XERCISE r ressure in u s 2 1. Upwa d P Liq id The B rometer 22 . a ’ 3 Bo e s Law 2 . yl 2 Dens t of ter 4.