<S,'J,S T|||.; SKNSK n I-' SKJIIT 



l>e seen, therefore, lli;il the visu:il :i 1 i| n CCIM I n Hi ol our ex I eriiM I world 

 i :i< ompli lied l>y (hnrt. Mild nnliu'd ri:.ni. The former lends to I he 

 loriinlioM of :in iniMi'c in llic I'oveii, MIM! I he |;i.l l.cr lo (lie I'orniM ! ion of 

 nil im.'ige upon I he more outlying district :; of I lie ielm:i. 



This discussion clciU'ly sIlOWH tint I lie V'isii;d :i\is M,lld I he ophc.'d 

 M\IM of I, lie eye MIV I u < > <li hncl f.'M'tofM. The former is the IIIIMIMUM ry 

 line :il<iii|', vvllicl) llic most distinct vision is ohtaint'd, l>ec;nise il con 

 necl s I he ohjccl u 1 1 h I In' IIH > I i n 1 1 i \ c :i i (;! nl I he rr| 1 1 1. !, (he |o\ c;i 

 i-cnl i :ih:: nl I he \clli\\ M|MI. Tin 1 l.'illrr is I lie Illir <>l inosl prrftvl, 

 iTl'r.'icI inn, I icc:ni;;r I |K> (lilVcrcnl i cl i ;ict i \ c innli.'i ol I he c\ r ;irr ccnl cri'd 

 Ujxui i|,. Tin' IIKP I h|c:il ;:\: li'in, nl c<uir;;c, i;. llic (inc in which the 

 1 1 -I i ;K I I\T i IK -i 1 1. 'i :i ic :K I j i is led III ;;ilch :i \v:i y I h.'il I hci c cci 1 1 r:i I i :i \ :i i c 



l.ltilll'.hl !<> :i precise I'dCIIS llpnll llic lno I c|i:lll\c IVf',1011 M| ihe |c 



cepldi. Tin;. I hue n|' I he pi K >l < )}',r:i | ill ic c:nner;i, luit mil nl' I he 

 lllllll.'lll '\c, liee:ni;,e I he |;il|er I I'l '( 1 1 lei 1 1 I \ slmu; ;i divergence of 

 1 1 ;; \ i MI: 1 1 :i nd i ipl H-.-I | ;i \e: i .1 I i i >IM !{.."i I o 7 degrees. 



ViMi.il Acuily. \iMiiher .'irgiinient in l:iv<ir ol lln- \ie\\ lh:il Ihe 

 cohe; :IM NIC ni< i :| i n 1 1 ti ul :i 1 1 1 eleineiil in \ i :H in i present ed I)V ihe 

 close correspondence lietueeii llic in;il|c I |MI ililc iiiuige Mild the 

 disposition of the COIK'S III Ihe lnve;i. S;d/,cl' h:i:; ;;||0\VII lllMl (I. Ill 

 lilin < >! I < >\ c:i >< in I :i i n . I ,'IS ci MIC , :i lid I ll.'l I Mil llllllllin.'i I ed sheel i; | >ci 

 eeived MS such 'inl\ ll eMch colic is the recipient ol ;il ICMS! one I'M \' ol 

 light. This necessil;i!c ;i lion I I III i :i v ; for e.-ich 0.01 mm", of fovc.-d 

 uil.'icc. Ill order li> olitiilll :i m<) :iic mipre ssion, (he (llllei'elil cones 

 mii:;l lie in\c:.lcd h\ :i /one ol noii stiiniil.'ited cone.;. < '. DuHois- 

 I > e \ i MI tin I " h;i c I i n 1:1 1 ct I the Iillliiliei ol i:i\ (hell re<|iiired M( 7'2 per 

 0.01 nun nl lo\ e;i I sin 1 1: ice. Th u: , : i < I < nililc : I :i i i recogm/,et| MS t \vo 

 ill Illicl liodlc. olll\ if (he dl:l:ilicc I >e( \\eeli I hem CoriX'Sponds to 

 ;i \r:ii:il Miiide of (>O seconds Omle : iinil.M rly , t\vo while lines di'M\vn 

 ;icio.:; ;i M;ick inl:icc. M re percei\'ed MS two lilies only if I he (list M lice 

 licluccli them Mililend ; ;i \l;;i|:d M!i!.',le of I'll In ,".', .ccolids. A I these 

 Mllgles, I he miMi'.e covers :i n :i re.'i ol O.OI I I. I o O.OO, i. mm '. i il re I HIM Mild 

 m\o|\es, therefore, two cone;, ol (he IOVCM. These experiments 

 :i l;.o ".\\< i\\ ( IIM! ( he \ i ;u.i I :icml \ doc liol differ gre.'ll ly \\ ll hill the fo\ CM, 

 Mild especiMllv noi \\ilhin the foveoln. (hitsnle the IOVCM, howev'cr, 

 the Mcmly diminishes very rapidly, ;ind Mlre:idy M( M di;;( :mce of 'JO 



<|egree :.. (he lilies ol (he HiiMi'.e mil: I lie scp:i ! :i I ei I I >y M dlstMIICC of 



Div.i mm in order to produce sepMi'Mle impressions. 



(!lllller\ IIMS c.lim.'ited (he si.c ot | he :m.illcs| perci'|)t ll>l(-' llllMge 

 M( O.OO.'KI mm'., (his \M!IIC lieing M|)plic;il)le only to the center ol (he 

 lo\ CM . / i , to the foveol.'i, I ''or I his del ermiiiM ( ion lie einploved M liL'ick 

 doi upon M \\hile h.-ickgroiind which VVMS gradually moved MWMV from 

 the e\e until it jiisl kiivK disappea red. \\hen thus just l>Mivly 

 producing u rrl.iiiMl st imul.'it ion, I lie si/e ol the inuige IIIMV l>e CM leu IM I ed 

 liy correlMl mi-, its distMiice Irom the eyes will) it s di.-uncter. Inde- 



1 I )i < ,.! l.'ilnin, Merlin. I SSI , 



n .i-lii lui I' \ ch unit l'h\ '.uil ilcr Sinncsiir^jinc, \ii, IS'.Mi. '.'IS 



