,,! ,,natural ,,& ,,artificial ,,dis9tegration ,,( ,,! ,,elem5ts ,,an ,,address ,,by ,pr(essor ,sir ,,erne/ ,,ru!r=d ,kt41 ,d4 ,sc41 ,,ll4 ,d41 ,ph4 ,d41 ,d4 ,phys41 ,f4 ,r4 ,s4 ,,on ,,! ,,occasion ,,( ,,! ,,c5t5>y ,,celebration ,,( ,,! ,,f\nd+ ,,( ,,! ,,frankl9 ,,in/itute ,,& ,,! ,,inauguration ,,ex]cises ,,( ,,! ,,b>tol ,,rese>* ,,f\ndation ,,septemb] #ag1 #ah1 #ai1 #aibd ,,! ,,frankl9 ,,in/itute ,,philadelphia ,,! ,,natural ,,& ,,artificial ,,dis9tegration ,,( ,,! ,,elem5ts ,by ,pr(essor ,sir ,,erne/ ,,ru!r=d1 ,kt41 ,d4 ,sc41 ,,ll4 ,d41 ,ph4 ,d41 ,d4 ,phys41 ,f4 ,r4 ,s4 ,,x is n my int5tion 9 ?is pap] to give a detail$ acc\nt ( ! natural dis9tegration ( ! radio elem5ts or ( ! me?ods employ$ to effect ! artificial dis9tegration ( c]ta9 light elem5ts4 ,i %all assume t y all h a g5]al k ( ! results ( ^! inve/igations1 b ,i %all conf9e myself to a consid]ation ( ! be>+ ( ^! results on our k ( ! /ructure ( ! nuclei ( atoms4 ,!re is n[ a g5]al agreem5t t ! atoms ( all elem5ts h a simil> electrical /ructure1 consi/+ ( a c5tral positively *>g$ nucleus surr\nd$ at a di/ance by ! appropriate numb] ( electrons4 ,f a /udy ( ! scatt]+ ( p>ticles by ! atoms ( matt] & f ! classical rese>*es ( ,moseley on ,x-ray spectra1 we "k t ! resultant positive *>ge on ! nucleus ( any atom1 9 t]ms ( ! fundam5tal unit ( electronic *>ge1 is giv5 num]ically by ! atomic or ord9al numb] ( ! elem5t1 due all[ance be+ made = miss+ elem5ts4 ,we "k t ) few exceptions all nucle> *>ges1 f #a = ! lighte/ atom1 hydrog51 to #ib = ! heavie/ elem5t1 uranium1 are repres5t$ by elem5ts f\nd 9 ! e>?4 ,! nucle> *>ge ( an elem5t controls ! numb] & di/ribution ( ! ext]nal electrons1 s t ! prop]ties ( an atom are def9$ by a :ole numb]1 repres5t+ its nucle> *>ge1 & are only to a m9or degree influ5c$ by ! mass or atomic weight ( ! atom4 ,?is m9ute b massive nucleus is1 9 a s5se1 a _w ( its own :i* is little1 if at all1 influ5c$ by ! ord9>y physical & *emical =ces at our comm&4 ,9 _m respects1 ! problem ( nucle> /ructure is mu* m difficult ?an ! correspond+ problem ( ! arrangem5t & motions ( ! planet>y electrons1 :]e we h a weal? ( available in=mation1 bo? physical & *emical1 to te/ ! adequacy ( our !ories4 ,! facts kn[n ab\t ! nucleus are few 9 numb] & ! me?ods ( attack to ?r[ light on its /ructure are limit$ 9 scope4 ,x is conv5i5t to di/+ui% betwe5 ! prop]ties assign$ to ! nucleus & ! planet>y electrons4 ,! movem5ts ( ! out] electrons are responsible = ! ,x-ray & optical spectra ( ! elem5ts & _! configuration = ! ord9>y physical & *emical prop]ties ( ! elem5t4 ,on ! o!r h&1 ! ph5om5a ( radioactivity & all prop]ties t dep5d on ! mass ( ! atom are to be def9itely assign$ to ! nucleus4 ,f a /udy ( ! radioactive trans=mations1 we "k t ! nucleus ( a heavy atom n only conta9s positively *>g$ bodies b also negative electrons1 s t ! nucle> *>ge is ! excess ( positive *>ge ov] negative4 ,9 rec5t ye>s1 ! g5]al idea has aris5 t !re are two def9ite fundam5tal units t h to d ) ! build+ up ( complex nuclei1 viz41 ! light negative electron & ! relatively massive hydrog5 nucleus :i* is believ$ to correspond to ! positive electron4 ,?is view has receiv$ v /rong support f ! exp]im5ts ( ,a/on on ,isotopes 9 :i* he has %[n t ! masses ( ! v>i\s species ( atoms are repres5t$ ne>ly by :ole numb]s 9 t]ms ( ,o #af4 ,f ! g5]al electric !ory1 x is to be anticipat$ t ! mass ( ! hydrog5 nucleus 9 ! nucleus /ructure w be some:at less ?an its value #a4jjgg 9 ! free /ate on acc\nt ( ! v close pack+ ( ! *>g$ units 9 ! conc5trat$ nucleus4 ,f ,a/on's exp]im5ts1 x appe>s t ! av]age mass ( ! hydrog5 nucleus1 or proton z x is n[ g5]ally call$1 is v ne>ly #a4jjj "u ^! conditions4 ,we %\ld anticipate t ! :ole numb] rule f\nd by ,a/on w\ld hold only to a fir/ approximation1 s9ce ! mass ( ! proton mu/ be to "s ext5t dep5d5t on ! detail$ /ructure ( ! nucleus4 ,9 ! case ( t9 & x5on ,a/on has already signaliz$ a def9ite dep>ture f ! :ole numb] rule1 & no d\bt a /ill m accurate det]m9ation ( ! masses ( ! atoms w disclose o!r diff]5ces ( a simil> k9d4 ,:ile our pres5t evid5ce indicates t ! proton & electron are ! fundam5tal con/itu5ts ( ! nucleus1 x is v probable t second>y comb9+ units play a prom95t "p 9 nucle> con/itution4 ,= example1 ! expulsion ( helium nuclei f ! radioactive bodies indicates t ! helium nucleus ( mass #d is probably a second>y unit ( great importance 9 atom build+4 ,on ! views outl9$1 we %\ld expect ! helium nucleus ( *>ge to be built up ( f\r protons & two electrons4 ,! loss ( mass 9 =m+ ?is nucleus indicates t a l>ge am\nt ( en]gy mu/ be lib]at$ dur+ its =mation4 ,if ?is be ! case1 ! helium nucleus mu/ be su* a /able /ructure t ! comb9$ en]gy ( f\r or five ( ! swifte/ p>ticles w\ld be necess>y to effect its disruption4 ,su* a d$uction is support$ by our failure to obs]ve any evid5ce ( dis9tegration ( ! swift p>ticle itself1 :e!r x is us$ to bomb>d matt] or :e!r ! p>ticle is us$ to bomb>d o!r helium atoms4 ,on ^! views1 we %\ld anticipate t ! nucleus ( radium ( atomic numb] #hh & atomic weight #bb4f conta9s 9 all #bbf protons ( mass #a & #ach electrons4 ,:ile ?is gives u ! num]ical relation betwe5 ! two fundam5tal units1 we h1 at pres5t1 no def9ite in=mation ( _! arrangem5t 9 ! m9ute nucle> volume1 nor ( ! nature & magnitude ( ! =ces t hold !m toge!r4 ,we %\ld anticipate t _m ( ! protons & electrons unite to =m second>y units1 e4 g4 helium nuclei1 & t ! detail$ /ructure ( ! nucleus may be v diff]5t f t to be expect$ if x consi/s ( a conglom]ation ( free protons & electrons4 ,x is ?us ( great importance to obta9 def9ite evid5ce ( ! nature & arrangem5t ( ! compon5ts ( ! nucleus & ( ! =ces t hold !m 9 equilibrium4 ,we %all n[ consid] "s ( ! l9es ( evid5ce :i* ?r[ light on ! actual dim5sions ( ! nucleus & ! law ( =ce op]ative 9 its neighborhood2 ! /ructure & modes ( vibration ( ! nucleus1 toge!r ) ! effects obs]v$ :5 "s light nuclei are dis9tegrat$ by bomb>dm5t ) p>ticles4 ,,dim5sions ,,( ,,! ,,nuclei ,,& ,,! ,,law ,,( ,,=ce ,! conception ( ! nucleus atom _h its orig9 9 #aiaa 9 ord] to expla9 ! scatt]+ ( an p>ticle ?r\gh a l>ge angle z ! result ( a s+le collision4 ,! obs]vation t ! p>ticle is 9 "s cases deflect$ ?r\gh m ?an a "r angle z ! result ( an enc\nt] ) a s+le atom fir/ br\ght to light ! int5se =ces t exi/ close to ! nucleus4 ,geig] & ,m>sd5 %[$ t ! numb] ( p>ticles scatt]$ ?r\gh diff]5t angles 0 9 close accord ) ! simple !ory :i* suppos$ t1 = ! di/ance involv$1 ! p>ticle & nucleus behav$ l *>g$ po9ts1 repell+ ea* o!r accord+ to ! law ( ! inv]se squ>e4 ,! accuracy ( ?is law has be5 indep5d5tly v]ifi$ by ,*adwick1 s t we are n[ c]ta9 t 9 a region close to ! nucleus ! ord9>y laws ( =ce are valid4 ,^! scatt]+ exp]im5ts also gave u ! fir/ idea z to ! probable dim5sions ( ! nuclei ( heavy atoms1 = x is to be anticipat$ t ! law ( ! inv]se squ>e mu/ break d[n if ! p>ticle approa*es closely to or actually ent]s ! nucle> /ructure4 ,?is v>iation 9 ! law ( =ce w\ld %[ itself by a diff]5ce betwe5 ! obs]v$ & calculat$ numb]s ( p>ticles scatt]$ ?r\gh l>ge angles4 ,geig] & ,m>sd51 h[ev]1 obs]v$ no c]ta9 v>iation ev5 :5 ! p>ticles ( range ab\t #d cms4 7 scatt]$ ?r\gh #ajj by a gold nucleus4 ,9 su* an enc\nt]1 ! close/ di/ance ( approa* ( ! p>ticle to ! c5t] ( ! nucleus is ab\t #e x #aj-ab cm41 s t x w\ld appe> t ! radius ( ! gold nucleus1 assum$ sph]ical1 c\ld n be mu* great] ?an ?is value4 ,!re is ano!r argum5t1 bas$ on radioactive data1 :i* gives a simil> value = ! dim5sions ( ! radius ( a heavy atom4 ,! p>ticle escap+ f ! nucleus increases 9 en]gy z x passes ?r\gh ! repulsive field ( ! nucleus4 ,to fix a m9imum limit1 suppose ! p>ticle f uranium1 :i* is ! sl[e/ ( all p>ticles expell$ f a nucleus1 ga9s all its en]gy f ! electro/atic field4 ,x c be calculat$ on ^! data t ! radius ( ! uranium nucleus _c be less ?an #f x #aj-ab cm4 ,?is is bas$ on ! assumption t ! =ces outside ! nucleus are repulsive & purely electro/atic4 ,if1 z seems n unlikely1 !re also exi/ close to ! nucleus /rong attractive =ces1 v>y+ m rapidly ?an an inv]se squ>e law1 ! actual dim5sions may be less ?an ! value calculat$ above4 ,at ?is /age ( our k x is ( great importance to te/ :e!r ! law ( =ce breaks d[n = ! di/ance ( close/ approa* ( an p>ticle to a nucleus4 ,?is c be done by comp>+ ! obs]v$ ) ! calculat$ numb] ( p>ticles scatt]$ ?r\gh angles ( ne>ly #ahj4 ,x seems almo/ c]ta9 t ! inv]se squ>e law mu/ break d[n :5 swift p>ticles are us$4 ,?is c be se5 f ! foll[+ argum5t4 ,if an p>ticle1 ( ! same spe$ z t eject$ dur+ ! trans=mation ( uranium1 is fir$ directly at ! uranium nucleus1 x mu/ p5etrate into ! nucle> /ructure4 ,if a /ill swift] p>ticle is us$1 e4 g4 t f radium ,c1 :i* has ab\t twice ! en]gy ( ! uranium p>ticle1 x is cle> t x mu/ p5etrate /ill m deeply into ! nucle> /ructure4 ,?is is bas$ on ! assumption t ! field due to a nucleus is approximately symmetrical 9 all directions4 ,if ?is is n true1 x may happ5 t only a fraction ( ! head-on collisions may be effective 9 p5etrat+ ! nucleus4 ,x is hop$ soon to attack ?is difficult problem exp]im5tally4 ,we h s f> dealt ) collisions ( an p>ticle ) a heavy atom4 ,we "k1 h[ev]1 f ! results ( ,ru!r=d1 ,*adwick & ,biel] t 9 a collision ( an p>ticle ) ! lighte/ atom1 hydrog51 ! law ( ! inv]se squ>e breaks d[n entirely :5 swift p>ticles are us$4 ,n only are ! numb]s ( ,h nuclei set 9 swift motion mu* great] ?an is to be expect$ 9 ! simple-po9t nucleus !ory1 b ! *ange ( numb] ) ! velocity ( ! p>ticle v>ies 9 ! opposite way f ! simple !ory4 ,su* wide dep>tures betwe5 !ory & exp]im5t are only explicable if we assume ei!r t ! nuclei h s5sible dim5sions or t ! inv]se squ>e law ( repulsion entirely breaks d[n 9 su* close collisions4 ,if we suppose ! complexity 9 /ructure & 9 laws ( =ce is to be ascrib$ to ! p>ticle r ?an to ! hydrog5 nucleus1 ,*adwick & ,biel]1 z ! result ( a c>eful s]ies ( exp]im5ts1 conclud$ t ! p>ticle behav$ z if x 7 a p]fectly ela/ic body1 sph]oidal 9 %ape ) its m9or axis #d x #aj-ac cm4 9 ! direction ( motion & major axis #h x #aj-ac cm4 ,outside ?is sph]oidal region ! =ces fell (f accord+ to ! ord9>y inv]se squ>e law1 b inside ?is region ! =ces increas$ s rapidly t a p>ticle 0 reflect$ f x z f a p]fectly ela/ic body4 ,no d\bt su* a conception is some:at artificial1 b x does s]ve to br+ out ! ess5tial po9ts involv$ 9 ! collision1 viz41 t :5 ! nuclei approa* )9 a c]ta9 critical di/ance ( ea* o!r1 =ces come into play :i* v>y m rapidly ?an ! inv]se squ>e4 ,x is difficult to ascribe ?is break-d[n ( ! law ( =ce m]ely to ! f9ite size or complexity ( ! nucle> /ructure or to its di/ortion1 b ! results r po9t to ! pres5ce ( new & unexpect$ =ces :i* come into play at su* small di/ances4 ,?is view has be5 confirm$ by "s rec5t exp]im5ts ( ,biel] 9 ! ,cav5di% ,laboratory 9 :i* he has made1 by scatt]+ me?ods1 a detail$ exam9ation ( ! law ( =ce 9 ! neighborhood ( a light nucleus l t ( alum9um4 ,= ?is purpose he comp>$ ! relative numb] ( p>ticles scatt]$ )9 ! same angul> limit f alum9um & f gold4 ,= ! range ( angles employ$1 viz41 up to #ajj1 x is assum$ t ! scatt]+ ( gold foll[s ! inv]se squ>e law4 ,he f\nd t ! ratio ( ! scatt]+ 9 alum9um comp>$ ) t 9 gold dep5d$ on ! velocity ( ! p>ticle4 ,= example1 = an p>ticle ( #c4d cms4 range1 ! !oretical ratio 0 obta9$ = angles ( deflection bel[ #dj b 0 ab\t #g p] c5t l[] = an av]age angle ( deflection ( #hj4 ,on ! o!r h&1 = swift] p>ticles ( range #f4f cms4 a dep>ture f ! !oretical ratio 0 mu* m m>k$ & am\nt$ to #bi p] c5t = an angle ( #hj4 ,9 ord] to acc\nt = ^! results he supposes t close to ! alum9um nucleus an attractive =ce is sup]impos$ on ! ord9>y repulsive =ces4 ,! results agre$ be/ ) ! assumption t ! attractive =ce v>ies accord+ to ! inv]se f\r? p[] ( ! di/ance & t ! =ces ( attraction & repulsion balanc$ at ab\t #c4d x #aj-ac cm4 f ! nucle> c5t]4 ,inside ?is critical radius ! =ces are entirely attractive2 outside !y are repulsive4 ,:ile we ne$ n lay too mu* /ress on ! accuracy ( ! actual value obta9$ or ( ! law ( attractive =ce1 we %all probably n be f> 9 error 9 suppos+ ! radius ( ! alum9um nucleus is n great] ?an #d x #aj-ac cm4 ,x is ( int]e/ to note t ! =ces betwe5 an p>ticle & a hydrog5 nucleus 7 f\nd to v>y rapidly at ab\t ! same di/ance4 ,x ?us seems cle> t ! dim5sions ( ! nuclei ( light atoms are small1 & almo/ unexpect$ly small 9 ! case ( alum9um :5 we rememb] t #bg protons & #ad electrons are conc5trat$ 9 su* a m9ute region4 ,! view t ! =ces betwe5 nuclei *ange f repulsion to attraction :5 !y are v close toge!r seems v probable1 = o!rwise x is exce$+ly difficult to und]/& :y a heavy nucleus ) a l>ge excess ( positive *>ge c hold toge!r 9 su* a conf9$ region4 ,we %all see t ! evid5ce f v>i\s o!r directions supports su* a conception1 b x is v unlikely t ! attractive =ces close to a complex nucleus c be express$ by any simple p[] law4 ,,radioactive ,,evid5ce ,a /udy ( ! long s]ies ( trans=mations :i* occur 9 uranium & ?orium provides u ) a weal? ( in=mation on ! modes ( dis9tegration ( atoms1 b un=tunately our !ories ( nucle> /ructure are n suffici5tly advanc$ to int]pret ^! data ) any detail4 ,! expulsion ( high spe$ & p>ticles f ! radioactive nucleus gives u "s idea ( ! p[]ful =ces resid5t 9 ! nucleus1 = x c be e/imat$ t ! en]gy ( emission ( ! p>ticle is 9 "s cases great] ?an ! en]gy t w\ld be acquir$ if ! p>ticle fell freely betwe5 two po9ts diff]+ 9 pot5tial by ab\t #d million volts4 ,! en]gies ( ! & rays are on a simil> scale ( magnitude4 ,not)/&+ our detail$ k ( ! successive trans=mation ( ! radio-elem5ts1 we h n s f> be5 able to obta9 any def9ite idea ( _! nucle> /ructure1 :ile ! cause ( ! dis9tegration is /ill a complete enigma4 ,9 comp>+ ! uranium1 ?orium1 & act9ium s]ies ( trans=mations1 "o _c fail to be /ruck by ! _m po9ts ( simil>ity 9 _! modes ( dis9tegration4 ,n only are ! radiations simil> 9 type & 9 en]gy1 b1 9 all cases1 ! end product is believ$ to be an isotope ( lead4 ,?is rem>kable simil>ity 9 ! modes ( trans=mation is especially exemplifi$ 9 ! case ( ! ,c bodies1 ea* ( :i* is kn[n to break up 9 at lea/ two di/9ct ways1 giv+ rise to bran* products4 ,= example1 ?orium ,c emits two types ( rays1 #fe p]c5t ( range #h4f cms4 & #ce p] c5t ( range #d4h cms41 & 9 addition "s rays4 ,9 ord] to expla9 ^! results1 x has be5 sugge/$ t a fraction ( ! atoms ( ?orium ,c break up fir/ ) ! expulsion ( an p>ticle & ! result+ product !n emits a p>ticle4 ,! o!r fraction breaks up 9 a rev]se way1 fir/ expell+ a p>ticle1 :ile ! subsequ5t product emits an p>ticle4 ,simil> dual *anges occur 9 radium ,c & act9ium ,c1 al?\gh ! relative numb] ( atoms 9 ea* bran* v>ies widely = ! diff]5t elem5ts4 ,?is rem>kable simil>ity betwe5 ! ,c bodies is /ill fur!r emphasiz$ by ! rec5t discov]y ( ,bates & ,rog]s t bo? radium ,c & ?orium ,c give rise 9 small numb]s to o!r gr\ps ( p>ticles1 "s ( !m mov+ at v high spe$s4 ,x has (t5 be5 a matt] ( rem>k t ! radioactive prop]ties ( ! ,c bodies seem to dep5d m on ! atomic numb]1 i4 e41 ! nucle> *>ge1 ?an on ! atomic weight4 ,conf9+ our att5tion to radium ,c & ?orium ,c1 :i* are be/ kn[n1 bo? h a nucle> *>ge #hc1 b ! atomic mass ( radium ,c is #bad & ( ?orium ,c #bab4 ,! nucleus ( radium ,c ?us conta9s two protons & two electrons m ?an t ( ?orium ,c4 ,if x 7 suppos$ t ! nuclei ( ^! elem5ts consi/$ ( a l>ge numb] ( *>g$ units 9 ceaseless & irregul> motion1 x is to be anticipat$ t ! addition ( ! protons & electrons to ! complex /ructure w\ld entirely alt] ! nucle> arrangem5t & consequ5tly its /ability & mode ( trans=mation4 ,on ! o!r h&1 we f9d t ! modes ( trans=mation ( ^! two nuclei h /rik+ & unexpect$ po9ts ( resemblance :i* are 9 entire disaccord ) su* a supposition4 ,we c1 h[ev]1 sugge/ a possible explanation ( ?is anomaly by suppos+ t ! & p>ticles :i* are lib]at$ f ^! elem5ts are n built deep into ! nucle> /ructure b exi/ z satellites ( a c5tral core :i* is common to bo? elem5ts4 ,^! satellites1 if 9 motion1 may be held 9 equilibrium by ! attractive =ces aris+ f ! core1 & ^! =ces w\ld be ! same = bo? elem5ts4 ,on ?is view ! manife/ations ( radioactivity are to be ascrib$ n to ! ma9 core1 b to ! satellite di/ribution1 :i* mu/ be some:at diff]5t = ! two elem5ts al?\gh possibly %[+ _m po9ts ( simil>ity4 ,x mu/ be admitt$ t a !ory ( ?is k9d is highly speculative1 b x does provide a useful work+ hypo!sis1 n only to acc\nt = ! simil>ity ( ! modes ( trans=mation ( ! two elem5ts b also imm$iately sugge/s a possible explanation ( ! lib]ation ( a numb] ( p>ticles ( diff]5t ranges f ! same elem5t4 ,!re are two ways ( reg>d+ ?is "q4 ,we may 9 ! fir/ place suppose t a c]ta9 am\nt ( surplus en]gy has to be lib]at$ 9 ! dis9tegration & t ?is en]gy may be giv5 to any "o ( a numb] ( satellites4 ,!re w be a c]ta9 probability t any p>ticul> p>ticle w be giv5 ?is en]gy1 & on ?is w dep5d ! relative numb] ( p>ticles 9 ! diff]5t ray gr\ps4 ,! ultimate en]gy ( ejection ( an p>ticle w dep5d on its position 9 ! field ( =ce surr\nd+ ! inn] core at ! mom5t ( its lib]ation4 ,on ! o!r h&1 we may suppose t ! same p>ticle is always eject$ b t ! p>ticle may occupy 9 ! atom "o ( a numb] ( /ation>y positions analog\s to ! /ation>y /ates ( ! electrons 9 ,bohr's !ory ( ! out] atom4 ,?is re/s on ! assumption t all ! atoms w n be id5tical 9 satellite /ructure b !re w be a numb] ( possible excit$ /ates ( ! atom z a consequ5ce ( ! previ\s dis9tegrations4 ,?is satellite !ory is useful 9 ano!r connection4 ,x has be5 sugge/$ t possibly ! high frequ5cy rays f a radioactive atom may arise n f ! movem5t ( ! electrons z ord9>ily suppos$1 b f ! transf] ( p>ticles f "o level to ano!r4 ,9 su* a case1 ! diff]5ce 9 en]gies betwe5 ! v>i\s gr\ps ( p>ticles f radium ,c & ?orium ,c %\ld be connect$ by ! quantum relation ) ! frequ5cies ( prom95t rays4 ,! evid5ce at pres5t available is n def9ite en\gh to give a f9al decision on ?is problem1 b po9ts to ! ne$ ( v accurate measurem5ts ( ! en]gies ( ! v>i\s gr\ps ( p>ticles4 ,on acc\nt ( ! relatively small numb] ( p>ticles 9 "s ( ! gr\ps1 ?is is difficult ( accompli%m5t4 ,9 consid]+ ! satellite !ory 9 connection ) ! radioactive bodies1 x is at fir/ sight natural to suppose1 s9ce ! end product ( bo? ! radium & ?orium s]ies is an isotope ( lead1 t "o ( ! isotopes ( lead =ms ! c5tral core4 ,x may1 h[ev]1 well be t ! radioactive processes cease :5 !re are /ill a numb] ( satellites rema9+4 ,if ?is be s1 ! core may be ( small] nucle> *>ge & mass ?an t ( lead4 ,f "s consid]ations1 describ$ lat]1 ?is core may correspond to an elem5t ne> plat9um ( numb] #gg & mass #aib4 ,,frequ5cy ,,( ,,vibration ,,( ,,! ,,nucleus ,"o ( ! mo/ int]e/+ & important me?ods ( ?r[+ light on nucle> /ructure is ! /udy ( ! v p5etrat+ rays expell$ by "s radioactive bodies4 ,! rays are id5tical 9 nature ) ,x-rays1 b ! mo/ p5etrat+ type ( rays consi/s ( waves ( mu* high] frequ5cy ?an c be produc$ 9 an ord9>y ,x-ray tube4 ,! "w ( ! la/ few ye>s has indicat$ v cle>ly t ! major "p ( ! radiation f bodies l radium ,b & ,c orig9ates 9 ! nucleus4 ,a det]m9ation ( ! frequ5cies ( ! rays ?us gives u direct in=mation on ! modes ( vibration ( p>ts ( ! nucle> /ructure4 ,! frequ5cy ( "s ( ! s(t] rays excit$ by radium ,b & radium ,c 0 measur$ by ! cry/al me?od by ,ru!r=d & ,&rade1 b x is difficult1 if n impossible1 by ?is me?od to det]m9e ! frequ5cies ( ! v p5etrat+ rays4 ,=tunately1 due l>gely to ! "w ( ,ellis & ,frule9 ,meitn]1 a new & p[]ful me?od has be5 devis$ = ?is purpose4 ,x is well kn[n t ! rays f radium ,b & radium ,c give a v]itable spectrum 9 a magnetic field1 %[+ ! pres5ce ( a numb] ( gr\ps ( rays ea* expell$ ) a def9ite spe$4 ,x is cle> t ea* ( ! gr\ps ( rays arises f conv]sion ( ! en]gy ( a ray ( def9ite frequ5cy into a ray 9 "o or o!r ( ! electronic levels 9 ! out] atom4 ,! en]gy requir$ to move an electron f "o ( ^! levels to ! outside ( ! atom is kn[n f a /udy ( ,x-ray absorption spectra4 ,! frequ5cy ( ! ray is ?us giv5 by ! quantum relation h ,e 1 :]e ,e is ! measur$ en]gy ( ! p>ticle4 ,s9ce ea* ray may be conv]t$ 9 any "o ( ! kn[n electronic levels 9 ! out] atom1 a s+le ray is responsible = ! appe>ance ( a numb] ( gr\ps ( rays1 correspond+ to conv]sion 9 ! ,k1 ,l1 ,m1 etc41 levels4 ,9 ?is way1 an analysis ( ! ray spectrum all[s u to fix ! frequ5cy ( ! m int5se rays :i* are emitt$ f ! nucleus4 ,! en]gy ( ! %orte/ wave measur$ 9 ?is way by ,ellis corresponds to m ?an two million volts1 :ile o!r evid5ce %[s t probably /ill %ort] waves are emitt$ 9 small quantity f radium ,c4 ,ellis & ,sk9n] h %[n t ! en]gies ( ^! rays %[ c]ta9 comb9ation diff]5ces1 su* z are s *>act]i/ic ( ! en]gies ( ! ,x-rays aris+ f ! out] electrons4 ,a s]ies ( en]gy levels may ?us be po/ulat$ 9 ! nucleus simil> 9 "* to ! electron levels ( ! out] atom1 & ! rays h _! orig9 9 ! fall ei!r ( an electron or ( an p>ticle betwe5 ^! levels4 ,?is is a significant & important result1 indicat+ t ! quantum dynamics c be appli$ to ! nucleus z well z to ! out] electronic /ructure4 ,! probability ( levels 9 ! nucle> /ructure is mo/ cle>ly se5 on ! satellite hypo!sis1 b 9 our ignorance ( ! laws ( =ce ne> ! core we are at ! mom5t unable to apply ! quantum dynamics directly to ! problem4 ,! outlook = fur!r advances 9 ?is direction is hopeful1 b is intimately connect$ ) a fur!r developm5t ( our k ( ! laws ( =ce t come into play close to ! nucleus 9 ! region occupi$ by ! satellites4 ,,artificial ,,dis9tegration ,,( ,,elem5ts ,we h se5 t x is believ$ t ! nuclei ( all atoms are compos$ ( protons & electrons & t ! numb] ( ea* ( ^! units 9 any nucleus c be d$uc$ f its mass & nucle> *>ge4 ,x is1 h[ev]1 at fir/ sight r surpris+ t no evid5ce ( ! individual exi/5ce ( protons 9 a nucleus is obta9$ f a /udy ( ! trans=mations ( ! radioactive elem5ts1 :]e ! processes occurr+ mu/ be suppos$ to be ( a v fundam5tal "*4 ,z f> z our obs]vations h gone1 electrons & helium nuclei1 b no protons1 are eject$ dur+ ! long s]ies ( trans=mations ( uranium1 ?orium & act9ium4 ,"o ( ! mo/ obvi\s me?ods = det]m9+ ! /ructure ( a nucleus is to f9d a me?od ( dis9tegrat+ x into its compon5t p>ts4 ,?is is done spontane\sly = u by nature to a limit$ ext5t 9 ! case ( ! heavy radioactive elem5ts1 b evid5ce ( ?is "* is n available 9 ! case ( ! ord9>y elem5ts4 ,z ! swift p>ticle f ! radioactive bodies is1 by f>1 ! mo/ en]getic projectile kn[n to u1 x seem$ f ! fir/ possible t occasionally ! nucleus ( a light atom might be dis9tegrat$ z ! result ( a close collision ) an p>ticle4 ,on acc\nt ( ! m9ute size ( ! nucleus1 x is to be anticipat$ t ! *ance ( a direct hit w\ld be v small & t consequ5tly ! dis9tegration effects1 if any1 w\ld be obs]v$ only on a v m9ute scale4 ,dur+ ! la/ few ye>s ,dr4 ,*adwick & ,i h obta9$ def9ite evid5ce t hydrog5 nuclei or protons c be remov$ by bomb>dm5t ( p>ticles f ! elem5ts boron1 nitrog51 fluor9e1 sodium1 alum9um & phosphorus4 ,9 ^! exp]im5ts ! pres5ce ( ,h nuclei is detect$ by ! sc9tillation me?od1 & _! maximum velocity ( ejection c be e/imat$ f ! ?ickness ( matt] :i* c be p5etrat$ by ^! p>ticles4 ,! numb] ( ,h nuclei eject$ ev5 9 ! mo/ favorable case is relatively v small comp>$ ) ! numb] ( bomb>d+ p>ticles1 viz41 ab\t "o 9 a million4 ,9 ^! exp]im5ts ! mat]ial subject to bomb>dm5t 0 plac$ imm$iately 9 front ( ! s\rce ( p>ticles & obs]vations on ! eject$ p>ticles 7 made on a z9c sulphide scre5 plac$ 9 a direct l9e a few c5timetres away4 ,us+ radium ,c z a s\rce ( rays1 ! ranges ( p5etration1 express$ 9 t]ms ( c5timetres ( air1 7 all 9 ^! cases great] ?an ! range ( free nuclei 7#cj cms4 9 air7 set 9 motion 9 hydrog5 by ! p>ticles4 ,by ins]t+ absorb+ scre5s ( #cj cms4 air equival5t 9 front ( ! z9c sulphide scre5 ! results 7 q indep5d5t ( ! pres5ce ( ei!r free or comb9$ hydrog5 z an impurity 9 ! bomb>d$ mat]ials4 ,"s ( ! light] elem5ts 7 exam9$ = absorptions less ?an ?is1 b1 9 g5]al1 ! numb] ( ,h p>ticles due to hydrog5 contam9ation ( ! s\rce & ! mat]ials 0 s l>ge t no confid5ce c\ld be plac$ 9 ! results4 ,9 su* exp]im5ts _m sc9tillations c be obs]v$1 b x is v difficult to decide :e!r ^! c be ascrib$ 9 "p to an actual dis9tegration ( ! mat]ial "u exam9ation4 ,! pres5ce ( long-range p>ticles ( ! ray type f ! s\rce ( radium ,c /ill fur!r complicates ! "q1 s9ce 9 g5]al ! numb] ( su* p>ticles is l>ge comp>$ ) ! dis9tegration effect we usually obs]ve4 ,to ov]come ^! difficulties1 inh]5t 9 ! direct me?od ( obs]vation1 ,dr4 ,*adwick & ,i h devis$ a simple me?od by :i* we c obs]ve ) c]ta9ty ! dis9tegration ( an elem5t :5 ! eject$ p>ticles h a range ( only #g cms4 9 air4 ,?is me?od is bas$ on ! assumption1 v]ifi$ 9 our previ\s exp]im5ts1 t ! dis9tegration p>ticles are emitt$ 9 all directions relative to ! incid5t rays4 ,a p[]ful beam ( rays falls on ! mat]ial to be exam9$ & ! lib]at$ p>ticles are obs]v$ at an av]age angle ( #ij to ! direction ( ! incid5t p>ticles4 ,by means ( scre5s x is arrang$ t no p>ticles c fall directly on ! z9c sulphide scre54 ,?is me?od has _m advantages4 ,we c n[ detect p>ticles ( range m ?an #g cms4 ) ! same c]ta9ty z p>ticles ( range above #cj cms4 9 our previ\s exp]im5ts1 = ! pres5ce ( hydrog5 9 ! bomb>d$ mat]ial has no effect4 ,?is c be %[n at once by bomb>d+ a scre5 ( p>aff9 wax1 :5 no p>ticles are obs]v$ on ! z9c sulphide scre54 ,on acc\nt ( ! v great r$uction 9 numb] ( ,h nuclei or p>ticles by scatt]+ ?r\gh #ij1 ! results are q indep5d5t ( ,h nuclei f ! s\rce or ( ! long-range p>ticles4 ,! latt] are j detectable "u our exp]im5tal conditions :5 a heavy elem5t l gold is us$ z scatt]+ mat]ial1 b are inappreciable = ! light] elem5ts4 ,a slight modification ( ! arrangem5t enables u to exam9e gases z well z solids4 ,work+ 9 ?is way we h f\nd t 9 addition to ! elem5ts boron1 nitrog51 fluor9e1 sodium1 alum9um1 & phosphorus1 :i* give ,h p>ticles ( maximum range 9 ! =w>d direction betwe5 #dj & #ij cms41 ! foll[+ give p>ticles ( range above #g cms43 neon1 magnesium1 silicon1 sulphur1 *lor9e1 argon1 & potassium4 ,! numb]s ( ! p>ticles emitt$ f ^! elem5ts are small comp>$ ) ! numb] f alum9um "u ! same conditions1 v>y+ betwe5 & 4 ,! ranges ( ! p>ticles h n be5 det]m9$ ) accuracy4 ,neon appe>s to give ! %orte/ range1 ab\t #af cms41 "u our conditions1 ! ranges ( ! o!rs ly+ betwe5 #ah cms4 & #cj cms4 ,by ! k9dness ( ,dr4 ,ros5ha9 we 7 able to make exp]im5ts ) a %eet ( metallic b]yllium4 ,?is gave a small effect1 ab\t ( t ( alum9um1 b we are n yet c]ta9 t x may n be due to ! pres5ce ( a small quantity ( fluor9e z an impurity4 ,! o!r light elem5ts1 hydrog51 helium1 li?ium1 c>bon1 & oxyg51 give no detectable effect beyond #g cms4 ,x is ( int]e/ to note t :ile c>bon & oxyg5 give no effect1 sulphur1 also probably a pure elem5t ( mass #dn1 gives an effect ( ne>ly "o-?ird t ( alum9um4 ,?is %[s cle>ly t ! sulphur nucleus is n built up solely ( helium nuclei1 a conclusion also sugge/$ by its atomic weight ( #cb4jg4 ,we h made a prelim9>y exam9ation ( ! elem5ts f calcium to iron1 b ) no def9ite results1 ow+ to ! difficulty ( obta9+ ^! elem5ts free f any ( ! active elem5ts1 9 p>ticul>1 nitrog54 ,= example1 :ile a piece ( electrolytic iron gave no p>ticles beyond #g cms41 a piece ( ,sw$i% iron gave a l>ge effect1 :i* 0 und\bt$ly due to ! pres5ce ( nitrog51 = aft] prolong$ heat+ 9 vacuo ! great] "p disappe>$4 ,simil> results 7 exp]i5c$ ) ! o!r elem5ts 9 ?is region4 ,we h obs]v$ no effects f ! foll[+ elem5ts3 nickel1 copp]1 z9c1 sel5ium1 krypton1 molybd5um1 palladium1 silv]1 t91 x5on1 gold & uranium4 ,! krypton & x5on 7 k9dly l5t by ,dr4 ,a/on4 ,,exam9ation ,,( ,,light ,,elem5ts ,,= ,,p>ticles ,,( ,,range ,,less ,,?an #c ,,cms4 ,,( ,,air ,:5 p>ticles are scatt]$ f light elem5ts1 ! simple !ory %[s t ! velocity ( ! scatt]$ p>ticles dep5ds on ! angle ( scatt]+4 ,= example1 us+ bomb>d+ p>ticles ( range #g cms41 ! range ( ! p>ticles scatt]$ ?r\gh m ?an #ij _c be great] ?an #a4j cm4 = li?ium 7#g71 #b4j cms4 = b]yllium 7#aj71 #b4e cms4 = c>bon1 #c4b cms4 = oxyg51 #d4c cms4 = alum9um1 & #f4h cms4 = gold4 ,provid$ we introduce suffici5t ?ickness ( absorb] to /op ! p>ticles scatt]$ ?r\gh #ij1 we c exam9e = dis9tegrat$ p>ticles f c>bon1 = example1 ^: range exce$s #b4e cms4 ,c]ta9 difficulties arise 9 ?is type ( exp]im5t :i* are abs5t :5 ! ?ickness ( absorb] is great] ?an #g cms42 any heavy elem5t pres5t z an impurity w give scatt]$ p>ticles ( range great] ?an ^? f c>bon & ?us complicate ! obs]vations4 ,9 addition1 s]i\s tr\bles may arise due to ! volatilization or escape ( active matt] f ! s\rce4 ,?is is especially m>k$ if ! vessel conta9+ ! radioactive s\rce is exhau/$4 ,to ov]come ?is difficulty1 we h f\nd x desirable to cov] ! s\rce ) a ?9 lay] ( celluloid ( #b or #c mm4 /opp+ p[] = rays4 ,by ?is proc$ure we h be5 able to avoid s]i\s contam9ation & to exam9e ! light] elem5ts by ?is me?od4 ,we h be5 unable to detect any appreciable numb] ( p>ticles f li?ium or c>bon = ranges great] ?an #c cms4 ,if c>bon %[s any effect at all1 x is c]ta9ly less ?an "o t5? ( ! numb] f alum9um "u ! same conditions4 ,?is is 9 entire disagreem5t ) ! "w ( ,kirs* & ,patt]son 7,nature1 ,april #bf1 #aibd71 :o f\nd evid5ce ( a l>ge numb] ( p>ticles f c>bon ( range #f cms4 ,a slight effect 0 obs]v$ 9 b]yllium 9 accordance ) our o!r exp]im5ts4 ,no effect 0 not$ 9 oxyg5 gas4 ,ap>t f b]yllium1 no c]ta9 effect has be5 not$ = elem5ts light] ?an boron4 ,"u ! conditions ( our exp]im5t1 x seems cle> t nei!r ,h nuclei nor o!r p>ticles ( range great] ?an #c cms4 c be lib]at$ 9 appreciable numb]s f ^! elem5ts 9 a direction at "r angles to ! bomb>d+ rays4 ,?is is1 9 a s5se1 a disappo9t+ result1 =1 unless ^! elem5ts are v firmly b\nd /ructures1 x 0 to be anticipat$ t an p>ticle bomb>dm5t w\ld resolve !m into _! con/itu5t p>ticles4 ,we hope to exam9e ?is :ole "q /ill m ?or\ghly1 z x is a matt] ( great importance to ! !ory ( nucle> con/itution to be c]ta9 :e!r or n ! light elem5ts c be dis9tegrat$ by swift p>ticles4 ,9 consid]+ ! results ( our new & old obs]vations1 "s po9ts ( /rik+ int]e/ em]ge4 ,9 ! fir/ place1 all ! elem5ts f fluor9e to potassium inclusive suff] dis9tegration "u ray bomb>dm5t4 ,z f> z our obs]vations h gone1 !re seems little d\bt t ! p>ticles eject$ f all ^! elem5ts are ,h nuclei4 ,! odd elem5ts1 ,b1 ,n1 ,f1 ,na1 ,al1 ,p1 all give long-range p>ticles v>y+ 9 range f #dj cms4 to #ij cms4 9 ! =w>d direction1 ! ev5 elem5ts1 ,c1 ,o1 ,ne1 ,mg1 ,si1 ,s1 ei!r give few p>ticles or none at all z 9 ! case ( ,c & ,o1 or give p>ticles ( mu* less range ?an ! adjac5t odd numb]$ elem5ts4 ,! diff]5ces betwe5 ! ranges ( ev5-odd elem5ts become mu* less m>k$ = elem5ts heavi] ?an phosphorus4 ,?is obvi\s diff]5ce 9 velocity ( expulsion ( ! ,h nuclei f ev5 & odd elem5ts is a matt] ( great int]e/4 ,su* a di/9ction c be p>allel$ by o!r obs]vations ( an entirely diff]5t "*4 ,h>k9s has %[n t elem5ts ( ev5 atomic numb] are mu* m abundant 9 ! e>?'s cru/ ?an elem5ts ( odd atomic numb]4 ,9 8 /udy ( ,isotopes1 ,a/on has %[n t 9 g5]al odd numb]$ elem5ts h only two isotopes diff]+ 9 mass by two units1 :ile ev5 numb]$ elem5ts 9 "s cases conta9 a l>ge numb] ( isotopes4 ,?is rem>kable di/9ction betwe5 ev5 & odd elem5ts _c b excite a lively curiosity1 b we c at pres5t only speculate on its und]ly+ cause4 ,,velocity ,,( ,,escape ,,( ,,hydrog5 ,,nuclei ,we h se5 t ! exp]im5ts ( ,biel] on ! scatt]+ ( rays by alum9um & magnesium indicate t a p[]ful attractive =ce comes into play v close to ! nuclei ( ^! atoms4 ,if ?is be ! case1 ! =ces ( attraction & repulsion mu/ balance at a c]ta9 di/ance f ! nucleus4 ,outside ?is critical po9t ! =ces on a positively *>g$ body are entirely repulsive4 ,c]ta9 important consequ5ces foll[ f ?is g5]al view ( nucle> =ces4 ,suppose1 = example1 t1 due to a collision ) a swift p>ticle1 a hydrog5 nucleus is lib]at$ f ! nucle> /ructure4 ,aft] pass+ across ! critical surface1 x w acquire en]gy 9 pass+ ?r\gh ! repulsive field4 ,x is cle>1 on ?is view1 t ! en]gy ( a *>g$ p>ticle aft] escape f ! atom _c be less ?an ! en]gy acquir$ 9 ! repulsive field2 consequ5tly we %\ld expect to f9d evid5ce t !re is a m9imum velocity ( escape ( a dis9tegration p>ticle4 ,we h obta9$ def9ite evid5ce ( su* an effect bo? 9 alum9um & sulphur by exam9+ ! absorption ( ,h nuclei f ^! elem5ts4 ,! numb] ( sc9tillations = a ?9 film 0 f\nd to be ne>ly con/ant = absorption betwe5 #g & #ab cms41 b falls (f rapidly = great] ?icknesses4 ,?is is exactly :at is to be expect$ on ! views outl9$4 ,no d\bt ! limit+ velocity v>ies some:at = ! diff]5t elem5ts1 b a l>ge am\nt ( exp]im5t w be requir$ to fix ?is limit ) accuracy4 ,f ^! results x is possible to =m a r\gh e/imate ( ! pot5tial ( ! field at ! critical surface1 & ?is comes out to be ab\t #c million volts = alum9um4 ,! value = sulphur is some:at great]4 ,?is br+s out 9 a /rik+ way ! extraord9>y smallness ( ! nuclei ( ^! elem5ts1 = x c be calculat$ t ! critical surface _c be di/ant m ?an #f x #aj-ac cm4 f ! c5tre ( ! nucleus4 ,^! d$uctions ( ! critical di/ance are 9 excell5t accord ) ^? made by ,biel] f obs]vations ( ! scatt]+ ( p>ticles4 ,ano!r important consequ5ce foll[s4 ,x is cle> t an p>ticle fir$ at ! nucleus w n be able to cross ?is critical surface & ?us be 9 a position to produce dis9tegration1 unless its velocity exce$s t correspond+ to ! critical pot5tial4 ,9 an exp]im5t made a few ye>s ago1 we f\nd t ! numb] ( ,h nuclei lib]at$ f alum9um fell (f rapidly ) dim9ution ( ! velocity ( ! p>ticle & 0 too small 9 numb] to detect :5 ! range ( ! p>ticle 0 less ?an #d4i cms4 ,?is corresponds to ! en]gy ( an p>ticle fall+ betwe5 ab\t #c million volts--a value 9 good accord ) t calculat$ f ! escape ( ,h nuclei4 ,fur!r exp]im5ts are requir$ ) o!r elem5ts to te/ if ?is relation betwe5 ! m9imum velocity ( ,h nuclei & ! m9imum velocity ( ! p>ticle to produce dis9tegration holds g5]ally2 b ! results z f> z !y g are c]ta9ly v sugge/ive4 ,x is ( int]e/ to note t ^! results af=d a def9ite pro( ( ! nucle> conception ( ! atom & give u "s hope t we may det]m9e ! magnitude ( ! critical pot5tial = a numb] ( ! light elem5ts4 ,,evolution ,,( ,,nuclei ,9 conclud+1 ,i w\ld l to make a few rem>ks ( a m speculative "* deal+ ) ! fundam5tal problem ( ! orig9 & evolution ( ! elem5ts f ! two fundam5tal build+ units1 ! positive & negative electrons4 ,x mu/ be confess$ t !re is little in=mation to guide u ) ! exception ( our k ( ! nucle> *>ges & masses ( ! v>i\s species ( elem5ts :i* survive to-day4 ,x has always be5 a matt] ( great difficulty to imag9e h[ ! m complex nuclei c be built up by ! successive additions ( protons & electrons1 s9ce ! proton mu/ be end[$ ) a v high spe$ to approa* closely to ! *>g$ nucleus4 ,i h already discuss$ 9 ?is pap] ! evid5ce t p[]ful attractive =ces v>y+ v rapidly ) ! di/ance are pres5t close to ! nucle> /ructure & x seems probable t ^! =ces mu/ ultimately be ascrib$ to ! con/itu5t proton4 ,9 su* a case x may be possible = an electron & proton to =m a v close comb9ation1 or neutron1 z ,i h t]m$ x4 ,! probable di/ance betwe5 ! c5tre ( ?is d\blet is ( ! ord] ( #c x #aj-ac cm4 ,! =ces betwe5 two neutrons w\ld be v small except = di/ance ( approa* ( ?is ord] ( magnitude1 & x is probable t ! neutrons w\ld collect toge!r 9 mu* ! same fa%ion z a numb] ( small movable magnets w\ld t5d to =m a coh]5t gr\p held toge!r by _! mutual =ces4 ,9 consid]+ ! orig9 ( ! elem5ts1 we may = simplicity suppose a l>ge diffus$ mass ( hydrog5 :i* is gradually heat$ by its gravitational cond5sation4 ,at high temp]atures ! gas w\ld consi/ ma9ly ( free hydrog5 nuclei & electrons1 & "s ( ^! w\ld 9 c\rse ( "t comb9e to =m neutrons1 emitt+ en]gy 9 ! process4 ,^! neutrons w\ld collect toge!r 9 nucle> masses ( all k9ds ( complexity4 ,n[ ! t5d5cy ( ! gr\ps ( neutrons w\ld be to =m m /able nucle> comb9ations1 su* z helium nuclei ( mass f\r1 & possibly int]m$iate /ages ( masses two & ?ree4 ,en]gy w\ld be emitt$ 9 ^! processes probably 9 ! =m ( swift surplus electrons :i* 7 n necess>y = ! /ability ( ! sy/em4 ,9 a s5se1 all ^! nucle> masses w\ld be radioactive1 b "s ( !m 9 _! trans=mation may rea* a /able configuration :i* w\ld repres5t ! nucleus ( "o ( our surviv+ elem5ts4 ,if we suppose t nucle> masses ov] a wide range ( mass c be =m$ be=e s]i\s trans=mation occurs1 x is easy to see h[ e possible type ( /able elem5t w gradually em]ge4 ,if we take ! helium nucleus z a comb9+ unit :i* emits 9 its =mation ! greate/ am\nt ( en]gy1 we %\ld ultimately expect _m ( ! neutrons 9 a heavy nucleus to =m helium nuclei4 ,^! helium nuclei w\ld t5d to collect toge!r & =m def9ite sy/ems & x seems n unlikely t !y w gr\p !mselves into ord]ly /ructures1 analog\s 9 "s respects to ! regul> arrangem5t ( atoms to =m cry/als1 b ) mu* small] di/ances betwe5 ! /ructural units4 ,9 su* a case1 "s ( ! elem5ts may consi/ ( a c5tral cry/al type ( /ructure ( helium nuclei surr\nd$ by positive & negatively *>g$ satellites 9 motion r\nd ?is c5tral core4 ,assum+ t su* ord]ly arrangem5ts ( helium nuclei are possible1 x is ( int]e/ to note t ! obs]v$ relations betwe5 atomic *>ge & atomic mass = ! elem5ts c be approximately obta9$ on a v simple assumption4 ,suppose t helium nuclei =m a po9t c5tr$ cubic lattice ) an electron at ! c5tre ( a cry/al unit ( eight helium nuclei4 ,a few ( ! possible types ( gr\p+ are giv5 9 ! foll[+ table1 ) correspond+ masses & nucle> *>ges4 ,! /ructure #d4 #c4 #b4 means a rectangul> arrangem5t ) sides conta9+ #d4 #c4 #b4 nuclei respectively4 ,x w ?us conta9 #bd helium nuclei1 h a mass #if1 & w conta9 #f intranucle> electrons4 ,its nucle> *>ge w !re=e be #dh - #f #da4 ,/ructural arrangem5t ( ,calculat$ ,calculat$ ,kn[n elem5t ( helium nuclei nucle> *>ge ,mass equal *>ge #c4 #b4 #b4 #bb #dh ,ti #dh #c4 #c4 #b4 #cb #gb ,ge #gd1 #gb1 #gj #c4 #c4 #c4 #df #ajh ,pd #ajf4g #d4 #b4 #b4 #bi #fd ,cu #fc4ce #d4 #c4 #b4 #db #if ,mo #if #d4 #c4 #c4 #fj #add ,nd #add #d4 #d4 #c4 #gh #aib ,pt #aie ,:ile ! agreem5t is f> f p]fect = all ^! /ructures1 !re is a g5]al accord ) obs]vation4 ,if we take ! view t "s ( ^! /ructures c gr[ by ! addition ( satellites1 !re is room = adju/m5t ( masses & to include ! int]v5+ elem5ts4 ,?is po9t ( view is admitt$ly v speculative & !re may well be o!r types ( /ructure involv$4 ,at ! same "t1 ! g5]al evid5ce sugge/s t !re are "s basal /ructures on :i* ! heavi] atoms are progressively built up4 ,! failure ( ! :ole numb] rule = ! mass ( isotopes1 obs]v$ 9 "s cases by ,a/on1 e4g41 betwe5 t9 & x5on1 c]ta9ly supports su* a conception4 ,f a /udy ( ! artificial dis9tegration ( ! elem5ts we h se5 t c>bon & oxyg5 repres5t v /able /ructures probably compos$ ( helium nuclei4 ,x is possible t oxyg5 nuclei1 = example1 may be ! /ructural basis ( "s ( ! elem5ts foll[+ oxyg51 b our in=mation is at pres5t too meagre to be at all c]ta9 on ?is po9t4 ,i ?9k1 h[ev]1 x w be cle> f ?is lecture :at a difficult b fasc9at+ problem is involv$ 9 ! /ructure ( nuclei4 ,be=e we c hope to make mu* advance1 x is ess5tial to "k m ( ! nature ( ! =ces op]ative close to protons & electrons1 & we may hope to acquire mu* in=mation by a detail$ /udy ( ! scatt]+ ( swift rays & rays by nuclei4 ,=tunately1 !re is n[ a numb] ( di/9ct l9es ( attack on ?is problem1 & f a comb9ation ( ! results obta9$ we may hope to make /eady1 if n rapid1 progress 9 ! solution ( ?is1 ! greate/ problem 9 ,physics4