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 1 
 
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 5 
 
 6 
 
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 VT: ): 
 
 
 
 
 LAUDET. 
 
 ^ illcmoir. 
 
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 ^ 
 
 
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 I 'ik l)ISTI!im:TI'lS Al 1 111 Mi KllM. Ill' 
 
 'iiii-: ];Kirisii association 
 
 AT N ( ) R W I ( ■ 1 1 
 
 i« .irc-CsV. 1803. 
 
 I . ( I N DON : 
 
 i; ASM, M O N I A i '. T 1' I C K i; R I '^ C 
 
 !.;(,, 1' I c r A I) 1 1. 1. V. 
 
 I SOS. 
 
 ^uMillliiHaH 
 

 ILtNTKD Iiv HANKF.N ANI> inMPANV. DKI'riV lli.rT 
 '-I MA t(V-r,H-^l i; \M. 
 
A. ( J>AIJDET, VMS 
 
 ^11 Memoir. 
 
 ^<ii;.\(K iilso lias li,.r martyrs: not tlio persecuted only, 
 lm( thost. too wIk, ,l,.vote themselves willing victims. Such 
 I'lc'ii, even it iipiuvciated, live in the past uncanonisea, 
 
 uotwithstand 
 
 -iiin 
 
 in;.;' tlie seventy of those penalties which tli 
 
 'r in tlu' cause of truth. Anion<i- the 
 
 inscribed 
 d. 
 
 ^y 
 
 names lately 
 
 on 
 
 melancholy death-roll, hero is one which 
 • Icsiu'ves mor(> (hau a jiassins" cxiu'essi.m of n^^-n-t. Clandet 
 
 lii'dal Chi 
 
 ■istmas. The ch'lay of this not 
 
 ico is, wo Lelieve. 
 
 not without advanta 
 
 ffe. 
 
 le man of 
 
 The repute of the photographer 
 IS more readily recognised than tho m(>rit of tl 
 seienco. Our sympathy is chi'dly with the latter, and 
 wilh deeds Avhich t;hed a brighter bistre wl 
 of po])ulan1y has subsided. Not that 
 
 len 
 
 th 
 
 levo)' 
 
 \v(^ would und(nTat( 
 
 tho valu(^ of ('lau(b«t's services to a beautiful and faseinatin 
 arl, an ail wJiich must always go hand-in-haud will 
 
 1 scieiiee 
 
 Those services have been beiu'flcial to society, and t'laudel 
 
 will 
 
 lo (heir 
 
 be nam 
 
 'd 
 
 wifli a small company of ingenious men, wl 
 
 lO 
 
 llnlKiUr, 
 
 ■a\e 
 
 phi 
 
 rraphy to (he world. V 
 
 et v.-<> 
 
 m 
 
 ay say, (lia( it was no( 
 
 merely (n (lie tame oT a jihdd 
 
 grapher that his genius aspired. !( was nn( tlia( |nr wl 
 
 llcll 
 
 a2 
 
 u 
 
 <•) .- »- rs 
 
he " Ronmofl dclijihts, and liv(>(l luborioufl dnyp." If, in 
 any dogroo, lie sacrili .mI in I'lutus, liis licai-t-liomago was 
 ut tho slirino of Mim'i'va. lie knew tliat niucli of tlio 
 ajijilaiiso wliicli liy his inihistry lie gained was bnt of an 
 I'lilirnicral natnrc : — 
 
 " TcnniiKit Iiorti dii'in, frriiiiiKf/ (iiic/or ojiiis.^' 
 
 Autoino Franr-nis Jean daudet was born at T^yons in 
 I7i)7, amid the soeial i-^ataolysm of the IJevohition, an 
 event that greatly eliangcd tlie prospects of his life, lie 
 was well edneated, and, at the age (jf twenty-one, entered 
 the office of his uncle, Monsieur Vital lioux, an eminent 
 hanker, who, a few years alter, placed liim at t]i(.> glass- 
 works 0. Choisy le lloi, as director in conjunction with 
 Monsieur G. Boniemjis, the well-known glass manufacturer. 
 Eventually ^l. Claudct came to London to introduce the pro- 
 ductions of Choisy.* In iS:!.'} h(^ invented tlu machine now 
 generally used for cutting all c\dindrical glass. For this 
 iuvcutiou Prince Albert awarded him the medal of tlu^ .Society 
 of Arts, hi IS.Vi. r)ut all tliis while he was :i student of 
 science, ti'aining and waiting for tlie object to wliich his trui> 
 lifo was to be devoted. The ])ath was opened to him l)y 
 the almost sinudfaneons realisations of photogniphy by 
 I)aguerro and Fox Talbot. In citing those well-known 
 names, we do not forget Xiepce, the noble pioneer of tho 
 
 * Xamcly, glass Hhadcs and shoot glass maJo in cylindtTs. This pursuit 
 brought him into rt.'Iations with .Mr. Lucas Chanci', of I'inniiighain, and 
 hcnco II. Claudot wa'a tho final cause of the institution of a new hraiu'h of 
 inanufact\iro in Knghmd. Indeed, tho inanufaitiiro of sheet glass hy this 
 method has since heen so largely developed, that it promises to supersede all 
 other means of making window-glass. 
 
pliotogr.ajiliie art. Tlis iinporf'cct results, and those of 
 AVedgwood, Davy, and others, had not aroused the interest 
 of men of seionco. Even tlio acliievemeut of DagueiTe was 
 received witli the coldness of ineredidity ; but Claudet saw 
 at onco the breadth and lioauty of the prospect It opened, 
 and dashed into photograpliy witli a warmth and resolution 
 tliat took his associates by siU'i)riso. He was by title a 
 " I'hotographer " before the name was known, or photo- 
 grapliy believed in. AVo romember him then. Ours was 
 tlio spring-time of life, his the meridian. AVe caught his 
 enthusiasm, we became his disciple — as who would not that 
 felt the inliuence of his gifts and acquirements, and witnessed 
 his uulliigging energy, his heroism of jiur^jose Y There he 
 would be, day after day, among the fumc^s of mercury and 
 iodine — careless of life or health — experimenting, })roduciug, 
 expounding, never tiring, never exliausting the fecundity of 
 his expedients, never dcspomling in liis asjiirations. And, 
 hapjiil}', lie was found rqual to what he undertook. AVlien 
 at first clieniistry had lo be called in aid, he was a cliemist 
 (as testifies Franoois Arago).* AVhen, later, optics had to be 
 appealed to, he was a mathematician ; when mechanical science 
 was to bo invoked — ln' was an ingenious mechanician; when 
 art was required, he was an artist of consummate* taste; 
 whatever new resources had to be sought, he was ever ready, 
 for the spark of genius was there, needing but the breath of 
 opportunity to fan it into the flame of achievement. 
 
 Thus qualified, Claudet (lb 10) took up photography as a 
 
 t " M. (.'laudet, nui u trouvc lu moyou Jo rcduirc h ijueliiUL'S eioronilcH l;i 
 (lun'o dV'Xiiositioii iliiiis li cluimljro uliscuru." — CEuvrcs complLtus ilo 
 Friin(,'ois Arugo. Toiiii.' vii., \\. oKi. 
 
T 
 
 i.l]iloRO]ilii(i inivsiiil ; iiml licnct'lui'fli. litrra' y, his dnvs wciv 
 
 (ll'Viitc:! ill tllC ]ir;ict !(•<■, liis llipllt-^ in tllc lIn'OVV dl' llir Ih'W 
 
 Mi'f iiud ni'iciici'. In t!i'^ lu'^-iiniiuir, (lie ]nMC('ilmv \v;is 
 iiiiturally inqioii'ei't, .'ind tliis, liy iiumLorlcss (Diidivaiici'y, In.' 
 Improved and roiideivd C(>vtain. Tliis was l\ >r 1 !ic 1 )agu(nTOo- 
 1 ypc — tlio ])li<)tugT!ii>hic picture upDii a iHili^hcd metal tal)Iel. 
 ill wliieli exquisite jiroeess lie somu hceaiuc the aeeoiiqilished 
 master. For Le it said in passini^'. tliat iiaper-jihotngraphy, 
 t]ie ealotyjH' (if l-'dx Tallmt, ihnn-ii already instituted, hud 
 nnt yet attaiiUMJ to pfactiral inTlectidn. 
 
 Till' first nntali'.' ri-^ult of Cjaudrt's ell'iirts was made 
 kniiwii in i'!imnmu'eati(ins tn the Aeadi'mii' dcs Sciences, and 
 t'l (he U"yal 8o ■ioty, on a metlmd nt' accclcratin;^' (he jmi- 
 iliiction (iF tlio image o!' t!ie iJa^-uerrcdlypc l,y the use (if 
 bromide and ohloriile of Iodine, as neficcd Lv "M. Ara^;(i.. 
 iibove. The operation was tlnis made a hundre(l times nuirc 
 rapid, ami henoo Claudot has the credit ef first renderln-i- 
 p(Xssiblo the eU'eetual portiaiture of animafe dlijects. Sd 
 scmsitivo had he now made his metal taLkt, that he dhtainc I 
 a portrait hy the oxyhydrog(^n li_<4'l>t in fifteen seconds ; an 
 impression of black lace by the li.u'ht ef (lie full niddii in fwd 
 mimites, and by the light (,f Hu. stars In fiflccn minufe,-- ; 
 an impression of a seid]itmvd figvu'e by (he light of a eaiidh' 
 in fifteen mimites, and (he same fiMm the light df a lamp 
 In hve muiutes ; and an Image of (he nidon in fdui' seconds. 
 
 ClaiKkt's mind was not of an order to l,(i satisfied with 
 results without Inquiring Info causes. His experiments, 
 th(>rofbre, soen yiehh'd him abundant o]>i)ortunitios of phlbi- 
 scphic invcstigatldu. \Vv find him Immediately after the 
 e.-.tabllshment df I )agnerr(.M)ty]ie, raising and answering 
 impdrtant .pie.>(idns : " What i« (he attlun df hght ,,ji the 
 
sonsitivo ooiitinp- ^ " "How docf? tlic morcuriiil vapoui' 
 prodiioo flm D/io'iion-r^otyito imiigi' r' " "A\niic]i are tho 
 purtir'nliir mys dl' lif^^lit Uiat inipjirt to tlio ('lioiiiical em-fUcG 
 tho af[inity fur lucivury ? " " AVIiat is tlio cause of tlio 
 •liUlroiiro in aclinniKitic loiisus Ijutwoeii fli(> visual r:i'l 
 lilioiogouic luci y AVliy do tlicy ooustautly vaiy 'i " " AVliat 
 aiv tlic lucaus of lucasuriiig lln' ]i]iotop;f'uie rays, and of 
 fiiidinj^' till' true focus at M']iic]i tiny produci' llie iuiago ':""' 
 Or, In a still widci' iicld nf pliysical scicrifc : " Aro tluTc 
 then pi'riddic changes in (he nature of the sun's light?" 
 These quciilidus and nian\' others he ans^verc(l fi'iini time to 
 lime in ]ia]iei's for scientihe socicti(>s, such as — "On the 
 chemieal aclinn of dilierent rays of tlie solar siieetnnn." — 
 "Oh tile dilierent prnperlies of solar rath'alion produciuif or 
 ]ircveuting a deposit of mercmy on silver jilates, (.V:e., 
 nuidifii'd l.iy coloured glass media." — ''On tlie use of a 
 polygon to ascertain the intensity of the liujit at dilierent 
 angles in (he phdto-room." — "On various ])henomona of 
 refraction through semi-lenses, i^c." Thus ho at once makes 
 Photography the handmaid of Science; his photographic 
 practice subserves the high consideratioiis of philoso[ihy ; and 
 whilst his hands are husily engaged in producing atbuirahlo 
 specimens of art, his head is oceupieil with ahsiruso questions 
 as to the properties of the agents employed, thi> chemieal 
 constituents of light, and the theory of optics. 
 
 (Jlaiulct's experiments in jiursuit of his inquiries were most 
 interesting. After d(>scrihing in detail his method of analysis 
 for the ]Mir]ios(> of discovering tlie photographic value of the 
 seveial rays of the sjicctrum, he says: "Thus we migjit 
 constnict a room lighted oidy through an inclosure of pale 
 yellow glass, in which light would lie very dazzling to the 
 
eyo, mid in lliis room no ])liotogTn]»lii(' (i])f>ra<i()n cnuld Til- 
 porfornu'd ; ur a rodni inclosiMl hy (lc(>|) blue ^'Jass, wliicli 
 would ajtpcar very dark, and in Avliich the iiliotograiiliio 
 operation would be nearly as rajiid as it would be in open 
 air." " Thus we may coucoive certain states of'the atniospliero 
 under which there will bo an abundance of illuminating rays, 
 and very lew iiliotogeuic rays ; and some others, under which 
 the reverse Avill take place." And he beneficently concludes 
 his exposition of the mysteries of lij^'ht, which are apt to 
 tantalise tlie photographer, by presenting liis l'hotogra]iho- 
 motre, which enables tlie operator to ascertain the (ju;di(y ol' 
 tlie light at any moment in tlie comparative ]ircv.".leHce oj' 
 deficiency of the photogenic rays. 80, when he iiad assm-ed 
 himself that in achromatic object-glasses, the photogenic and 
 the visual focus do not generally coineich; — and, moreover, 
 tliat tliere is a conthmal variation between the two foci — lie 
 did not rest witli the mere exposition of tliese curious facts, 
 but at the same time brought fonvard for the use of ])hoto- 
 grajihers his Focimetre, to enable them to find the din'eicnces 
 Itetween tlie two foci, ami to discover Uw place of the 
 photogenic focus at the moment of oiievating. AVlien treat- 
 ing on this subject he gives a problem to the opticians — 
 whether it would be jiossible to ]ir(jduce an olyect-glass in 
 which the two foci should be wvy little separated, or even 
 coincide 'r And again, since, in some imacconntable way, 
 object-glasses will differ in their quality as to the degree of 
 separation or coincidence of the two foci, he, when declaring 
 this, also brings forward his I>ynactiuometrc — for measm-ing 
 the actinic or photogenic power of object glasses. This 
 instrument isidso a I'hotometre — for measui-iug the intensity 
 of pliotogouic light. 
 
PI, , liipiwuppilll II I 
 
 ■■iii 
 
 9 
 
 J*\ir somo years M. riauclot had, as a pliotograjtliormproly, 
 a spocialit y in his supcnoi' knowUMlge, skill, iiiid ri'sourcfs 
 wilh rcgiu'd to tlie jirofcss of Daguorro. Jiiit when tlio 
 iiivc'iitioii oi' Fox Talhot hud liccii porfected in tlio adoption 
 of glass tablets, {'uhiiinating in tho adaptation of the 
 ingenious Archer — the collodion film — the glory of Daguern^ 
 Itegan to decline, and before long his prophet had, how- 
 ever unwillingly, to give uji by degrees, the incomparable 
 Dagueri'eiitype. The sujierior convenience and applicability 
 of 1 he 'Palbi it-type ju'ocess out -value(l the exipdsite detail — 
 the id)sulu1e ]ierf'ectio]i — of tin* Daguerreotyiie. Xor was 
 ( 'laudet less able iis the iiiteriiretei of the Archer-type than 
 he bad beeu of the invention of the Frenclnuan. And, 
 fortunately, there ciinie a solace iu tliat beautiful and philo- 
 sophical uistrument — the Stereoscope. ('laudet was here 
 auain tlu^ first to a]i[ireciate and a(b)[)t. lie assisted Sir 
 Clmi'les Wheatstone in the early a]i[>licatIon of the stereo- 
 scojie to ]ihotogni]ihy ; he comprehended and (wpounded 
 its scientific priui'iples, and did ;dl that an ingenious admirer 
 could to give it to the world. His enthusiasm was inib'cd 
 as warm lor tlie sti>reoscopt; as it had been earlier for 
 ]ihotograiihy itself It was, he said, the complement of 
 ]iliotograpliy ; it was by tlie aid of iihotography alone that 
 the principles of the stereoseo[)e could be efi'ectually exhibited; 
 whilst from the ajijilicatlou of the stereoscope, the art of 
 photography derived iiuTcased interest and value. AV'ith 
 the true instinct of the man of science, ho saw that the two 
 must eombino to demonstnvto the laws of vision. In his 
 admirable treatise on tho stereoscope, he says : " It is essential, 
 in the liiEtory of this art, to give the theory of the principles 
 of Liuocular vision, accompanied by practical details of the 
 
10 
 
 mnmu'v ofobtniiiiiip' tlioBo imnpos of wliich llio ronjuncfidii 
 
 is tllC HKll'VcllnllS JillclliillH'lUill dl' (illjccts ill Vl'HlT, Si i tll.'ll 
 
 ilioy iiji]iciiv iis ir tlicv were really willds — with an illusidii 
 Kiifh as that one fch'Iiis alilc in ^v'v/.r lluiii Avilli llic 
 liaiid." And lu; jn'oceids, us uMial with liiin, to explain 
 Ilia " Binocular Camera," wliicli lie says ''apponrs to ni(Mo 
 meet all tlio exigeneies of etiavoscoiiic ]iliii|d,Lrra]iliy." And 
 lliat his zeal (o satisfy these " exip'iicies " did iidt over- 
 \\lielm si'i'iienius iiiqnilses lur the ]ileasuns and advantages 
 of society, witness an elii(|uent passage on Ihe steredseepe 
 tVom one of his pajiers : — 
 
 " 'I'lic storcD.sdijic is tlu' <,'i'ncral jiaiKirania of tlir wnild. It l)iiiii.'s 
 to us ill till' chcaiH'-ii ami iii>-st ]ier!alilc ferui, iml eiily the iiiiiirc. 
 Iiilt tlie iiumIcI, ill ii tilligilile slia|ii'. of all tliat exists in tlir vain, is 
 countries of the .u'lolic ; it iiitroiluecs us to scenes known only IVoin 
 the iiii|ielt';'et li'lalions of travellers; it leails us lufiive the luilis of 
 iintii[ue arehileelure, illustrating;' ihe liistorieal reeonls of former and 
 lost eivilisations, the inaiius, taste, ami jiower of ]iast a,L:es, \vilh which 
 we ha\e lieeoiiie as familiarisi'il as if we had visited them. |',y oiii 
 tireside we have the ad'. aiitaue of exaniiniiij,' thelii, withoiit lieiii!;' 
 exposed to the faliuue. jrivatioii, and risks of the dariuj;; and I'liter- 
 |irisin,i,' artists who. for our ;zratilieation and instruotioii, iiave 
 traversed lands ami seas, crossed riversaml \alleys. ascended rocks and 
 inountains with their luav.y and e.nniliu/us pholo.L:raiihic ba^'^ae-e." 
 
 CLindet was eiidoAved hy nature to lie an investi"'ator. 
 A watchful and sagacious ohserver, he was (jiiick to delect 
 eoiueideuccs or exce]itions, iind untiring in juirsuit. Thus, 
 in his paper on "Tlie I'henoinenon of Ihe lielief of the 
 Image," lio ohserved, " thtit the image fonned fni the ground 
 glass of the camera ohsoura, appears as nnich in relief as 
 the natm-al ohject wlu'U seen with two eyi^s, and his ex]>eri- 
 moiits have disclosed the singular iuid unexiiected fact, that 
 iilthough only one image miiis depicted on the ground glass, 
 
 Ki 
 
■^wawipupBP^ 
 
 yet ciicli cyi' iicmnvcs a 'lilfiMviit imagv. Tlif imago seen 
 ii\- till" ri"lit eve is lln' r(>]iri'si'ii1iiti<tu nTriU'tiMl liy tlic li'i'l 
 sido ol' llii' lens," iiiul rirr rcrxK. " (Jonsi.'qucutly, llio;<o t\v<> 
 iumgi'3 proHL'utiiig 1\vi» AiU'crcjit porsiuH'tivos, tlie result is a 
 Hturoosciipii' ]perfoiitiijii, us wlicu wo l(jok throiigli tlici btcreo- 
 scujio at twi) imagt.'s of Lliircrcnt povspcctives." llo tlu'ii 
 cNpliiiiis Oiat \\i\ nsctcrtaincMl tlicsc facts by many oxporimcuts, 
 ••till' most di'cisivi' of whii'li cuiislsts in ]i!ai'ing lieforo one 
 of the miir-inal openings of tlif lens ;i liluc glass, and 
 before llie (.llii-i' a yellow glass. The ivsnlt is two images 
 sni'iTposod on the scr.'i'u of ll\i' i-anu'm. ouo yellow, the 
 nlher blue, farming on.' image of a grey tint, the mixture of 
 \r||ow and lilui', wiii'ii \vi' look \vi i hoth oycs at an eijual 
 di, lance IVi.m the centre. ISut when 've shut alternately, 
 now the right ey<' and llicii tlie left .ye, the image appears 
 lirsf vcllow, snid second liiuc" Again, in his very elaborate 
 pai.er"On the Laws which regulate the Conjugate Foci." 
 written with a view io relieve photograjiliers from the 
 uncertainty and trouble <i!' .setting tlie iocus, be says : " That 
 the ]iroiMU-tion of the image is in an inverse ratio to the 
 distiuice of objects, is i'^ law whicli is exacl only for the 
 camera ob.seura. without lens. I'mt when th(> opening of the 
 camera is suiiplied with a lens, some new principle niodilles 
 tin; cah'ulation. and the ccmsocpience is, that the distances ol 
 objects and local distances nuist be measured, m^t from tlie 
 bole of tlio camera or from the lens, but from certain points 
 distant from the lens on both sides, and the position of which 
 varies according to the ]n>wer and curvature of the lens. 
 
 " I have (mdeavounnl to solve that problem, and 1 think 
 I havi' f<mnd the m(>aus of setting the I'ociis by some sure 
 and fixed rules ada[ited to all kinds of lenses, thereby 
 
12 
 
 onablinp every pliofojrrnplir'r in find tlio \\\cn] (lislmici' f'l'v 
 any given distance oi' olijccls, and rirc rcrsa, jiiid rurllicr 
 enabling him to determine botli lliese distances Inr any 
 degree of reduetion or aniiilifieation ol' iniiige." And to 
 his ilhistrations lie adils : " J»y these ('xanijiles we conceive 
 what is meant by approaching the inlinite and never reach- 
 ing it." 
 
 Claudot's unswerving purpose wns to e]eva1i> Photography 
 by rendering her work seientifieally true. In one of his 
 papers on the optics of iihotogra]ihy he writes: " ()n(> of 
 the greatest dcficiences of photograji'iy in the representation 
 of solid figures is the incajiabilily of dbtaining a well-(h'llned 
 imago of all the various parts situated on dilfereut planes. 
 * * * * * My object has '...^'u to discover a method of 
 removing, if possible, from photogra]ihie portraiture, that 
 mechanical harshness whicli results from tlie action of the 
 most perfect lens(>s. In llie best works nf art, the eifects are 
 produced by a soft and liarmoniDUs treatment," i^c. 8uch 
 studies led later to "The Self-acting Focus E(pudiser, oi' 
 the means of producing the diifeivntiid movement of thi' 
 two lenses of a photograjihie optical condtination, wln'ch is 
 capable, during the exposure, of bringing consecutively all 
 ■■tho planes of a solid figure into focus, without altering the 
 size of the various iiuages superpo.scd." lie relates that he 
 submitted the plan to M. Voigtlauder, who " chargiMl his 
 step-son, Dr. Somner, to calculate," iK;e. " l)r. Sonmer soon 
 sent me a series of formuUc showing that, although lor all 
 practical purposes iu photography, the nKJvement I had 
 proposed fulfilled the object iu vit'W, yet that a more 
 scientific cousideratiou called for a modification, t.'te. * * * 
 This presented another diilicult problem, the solution of 
 
 t' 
 
|;{ 
 
 I' 
 
 which was indocd most porploxirig. But T did not liko that 
 it should lio siiid my ]>l!vn was not entirely in iiocordanee 
 witli the matiieniiitical laws of opties, and 1 set to work to 
 (iiid ii ineelianieal means ])y wliirli I eould avail myself of 
 the (!al(;ulati(jns of Dr. Soniner. I have found such means 
 and it proves that the diirerential movement can bo effected 
 not oidy as readily, hut with a pr(;ater command and steadi- 
 ness than by moving only one lens." 
 
 Claudet had truly a fruitl'ul source of interest in tlie science 
 of photogra]ihy. Scarcely had lit> solved one lu-oblem when 
 lie was immersed in another. His inquiry into the causes 
 of "the relief of the image," above adverted to, IimI aiter 
 a while to llu; beautiful illustration seen in the Stercomf)no- 
 scopc. It' it bo proved that tho olfect of relief observed on 
 the screen of the camera is caused by the combinati(m of 
 tho two images of diiferent lun'speetives, one from the right 
 side of the lens, tho other from tlio left side, and If tlie same 
 olfect of relief results from two photograjihs of diiferent 
 perspectives superposed by the stereoscope, then it should 
 occur that by refracting two images of diiferent perspectiv<s 
 upon a ground glass screen by means of an adjustment 
 whicli sliall bring them to coincide, wo shall in like manner 
 obtain tho ellect of relief. Tho steroomonoscopc then 
 produces ouq object in relief from two Hat pictiu'os — a 
 statue in ]H'r('ect symmetry and solidity by tho combination 
 of two images from photographs of dillerent p(,'rspcctives ; 
 and the result is not (tnly beautiful to tho vision, but in 
 its scientific princii)les highly interesting. Such was the 
 Stereomonoscope, only eons})ieuous among Claudet's coimtless 
 devices for faeilitating and perfecting the procedure of 
 photography. Sometimes, too, he allowed himself to stray 
 
1 1 
 
 a 
 
 I'nun liis clili'l' i.v,'Uiliii ('I' ilclijjlif iiitn iiutlviiit;' ]i!itli< ; iiii<l 
 wi' liml liiin :it lln' I'-riti-h As^dciiitiMH ties. r'lpiiii>' his 
 "Slur ( 'Iii-(iiiintM-Jcii|i(' "-Mil iiistniin''iit t'nr cxiiiiiiiiiiiy- mihI 
 coiiiiiiiriii;^ till- niys nl' llic slars," TIk' ]Mii|MP<i' nl' tliis 
 iuHtrmucnt is " lo dcvclni) an iiifluitcly .'-m;!!! spul nl' li^lil 
 iiiti) (I l.'irgo cli'clc, cxliiliitiiiji' mi its ]i('riii]irry, tlic viirinus 
 iiiy.s ('iiiitfcil liy llic star, all rciUnwiii;,' cai'li dtlicr in spacrs 
 corrcspimdhig-with tlicir tliimtion ; i^Iiowin^' alsn lilaiik s]ia<'cs 
 liclw'oon two couti.ij^umis riiys, corrcRiKiiKliiif;- willi tlic lilack 
 lilies of tlic sjM'ctnim. Wi' Iiavr, in I'lict, a s] km In >?-(•( ijic liy 
 wliich \vc can analyse tlu' ]iarlicular liiilit of any star; aial 
 fiiriluT, liy tills iiislrnini'iit we may anive at the discoveiy 
 nl' tlie real cause ol' tlie scintillation, and cnni]iare its intensity 
 in various cliniides ami at (liU'erent allifiales ol'u giv( n star." 
 < )r, again, we liave ii discoiu'so "on inn\iii;.;- ]iliot(igra]iliie 
 llg'iu'os, illustrating some phenomena ol' vision (onnected 
 with tlio condiiualioii of Stereoscope and the i'lienaklslo- 
 seope, 1)y means of photngTaiiliy." "()nr sensation of 
 vision," he says, "is not in tlio eyes, hut only in the single 
 ceiisoriuin of vision, to wlueli liotli o_yps convey their separate 
 peiveptioii^'." Again, he gives us "A new fact relating to 
 liinocular vision," to illustrate the persistence of the im- 
 pre-^sion made liy light upon the retina. At the conclusion 
 of this pajier he modestly as Justly adds, that Professor 
 Wheatstoiie liy his adnurahle discovery — the I'scaidoscope — 
 has left very little for furthi'r investigation in the pliysiulogy 
 of biuocular vision. He expounds with generous jiraiso 
 the inventions of others, as in his ]iapcr"()n the princi|iles 
 of the Solar camera." "Such ho says, "is the essential 
 principle of ^V'oodwar(^s solar canieia. * * * * 'Pl,is 
 ]irinciple is truly marvellous. ' * * ^\'ithout (piestion. 
 
 I 
 
 '' 
 
 i 
 
 I 
 
15 
 
 its intrntliiitidii iiif'i tin' iilintopriiplicr's hIikIIh will murk i 
 pcriiid 1)1' cciiisiilcrnlil'' iiii]irii\iiii"iit in llic Jirt." 
 
 N'if. whil'-l \v>' iiniiil tn ('liiiidi'l !is II |iliil(is(iiihcr, it wouM 
 lie less lliau juflicc ikjI to nM'oj^niisc liis nliilily iis an artist, 
 unci his grciil t^crviccs to tlio art of iiliotogTiipliy. He imt 
 ciiily liiuisolt' produced bwiutii'iil and porftM-'t works in plioto- 
 <;riipliy, liut WMH aisociuiiu'iitiy, l)y lis studios aud inventions. 
 tli(MU(>un« of eniililin^- others to r(»fhi(.' aud advanee the ait. 
 Ho WiiH, indeed, the ehaniiaiju of p!i(jto^'rapliy as an art. 
 When the nniua,!4'ers i,i i .( L'niversal Exliiliilion of JSfl'j 
 had plac'iid photograiihy in the lueeliaiiieal ([e['artnient, he 
 eniergtnl limn tlie laboratory into the studio, and, lance in 
 re.-t, chivalrously prochiinu'd pliotography one of the lini' 
 arts against all comers, ".I am oue of those, "" he says, in 
 on(! of his printed letters of that date, " who are convinced 
 that [photography deserves tu he ranked among tlie (hie 
 arts, if ]ihotography was only a machine, such as a magic 
 lantern, with which every one can striiio [lictm'es on a wliite 
 screen with the same success, its productions miglit indeed 
 lie e\hi1iite(l in the mechanical department ; but as 1 Und 
 I'roin my own e.\[jerii'nce, which is as old as [ihotography 
 itself, that uuthing is more dillieult than t(j }iroduce ]ihoto- 
 graphs deserving to be looked at — that it rc(juires thought, 
 tavste, judgment, and relint'mcnt to use with success the 
 apliaratus mid the process — 1 consider there is as much arl 
 in the result as in any of the so-calk'd tine arts." 
 
 ( 'laudet's seientilic relations with ISir David iU'ewster had 
 a ' aH'c'cting couelusiou. The two philosophers, for some 
 m> iths during last year, were concurreutly engaged in 
 investigating an interesting point in the ojitics of photo- 
 graphy. 'Pile corres]iondenc(^ \\as broken — never to be 
 
ronowod — by tlio (loath of'oiio. Tlio ollior, sixtoni yoars tin' 
 senior, iindei'tnok to write a iiKMiioir of his IricniL In u 
 letter (hitcd " Allcrly, Meh'ose, Jiuuiarv I, ISdS," adiU-essfil 
 to Mr. Frederic ('kiudet, lie says of CHaudet : " His soientific 
 acquirements and his iiivontivo genius were nf a very higli 
 order, and his kind nature and generous eliaracter will he 
 acknowledged by all who had the ])leasure of knowing- 
 him." 
 
 "I shall be glad to do anything you desire that can dn 
 lionour to his memory, and I will tliank you to send me tlu" 
 fullest information in your power respecting his early as well 
 as liis later life and inventions." * * « 
 
 Six weeks later, " that old man eloquent " jiassed away, 
 and the full testimony he woidd have boriH> to the scientifli' 
 woi-th of Claudet — is not. 
 
 The chief subject of the letters of Brewster above referred 
 to, is the greater perfection of photo-poi-traiturc by nieans 
 of small lenses made of materials of dilFerent dispersivi^ 
 powers, with a view to obtaining a depth of focus unattain- 
 able with glass lenses. These letters are indeed siu'prising 
 instances of vigom* and freshness of intellect in a nuiu of 8(J. 
 The extracts at foot will, we think, be their own apology.* 
 
 • .l/a>'(;A22, 1807. — I am persuadud that the great desideratum in photography, 
 
 whether monociihir or binocular, is the perfect iaii af the picture on tin; camera. 
 I am certain that dill'crent cameras, even wlicn the lonscH are corrected for 
 colour and aberration, do not give t/ie same likniens. 
 
 This imperfection obviously ari.sc.s from the dilTcrent ai>erturc.s of the lenn, 
 in a great measure, but I believe also frum the number and form of the 
 separate lenses. 
 
 An iniinitely small pin-hole is the most perfect camera, and the nearer wo 
 can ajijiroach to the smallest and thinnest lens, the nearer do wo ajiproaeh to 
 a perfect portrait. 
 
 The extreme aensitiveneaa of thc^ process enables the photographer to 
 
 i 
 
 >l 
 
17 
 
 i 
 
 Tlli> latest .jniut il,Vcsli,o,,li,,U nC ]!roWf;t,T i„|,l ChuuU is 
 
 il''SfTil)c(l ii, a iii.'m(,r;ni.luiii liy llic hitter: - i tried ;- l,.iis 
 "f ;'<'<'1< crysjiil tin„-,i..!,n„n;itie .■unl simply .I,,,,!,!,. .•n„veN. 
 
 Silei, ,.,s tl|.,se , sr.l lor ..nini.KMl speef acl,.>. I n,„.,,.(e.l VvitI, 
 
 '"'^'1"'<"''""I'''1""|* ''.■'If.'ni inelu ln,t tin- ]..,is WW n,,,,- 
 
 '•'■'l"n.. ),i.s l,ns to tlm siz,. of the l„„„ui, ,..,,,il, whi.h is »},sol„t,.|v n,.,.,s. 
 SUIT to l.r...lu,,.|h<. portrait of tho person wliom w,. ;ut,i:.llv s-n, 1,,,'t so,,,,- 
 tin,,;,' ulso .lop,.n,Is on the p,.rlV,.t homog,,.n,.ity of th. glas. r„,plov,.,l. n„.l ,,| 
 the niiiiilHT iiikI ciirvatiin^ of tl,.. voiVa.lin^' s„rfiuvs. 
 
 No proptT ox|i,.,i„„„t l,;,.s y.t 1,,.,.,, >„,ulo to as. ,tain tho oPcl „f a ,si„.^l,. 
 l.'ns of dianion,! or a„y othor s,.t,.stanfo. J wish yoa wo„l,l ,„t.r „po„ tin, 
 i'i<|iniy. Y,„i aro tho only jMTson I know /itt(?d to do i<. 
 
 Jpvil IS, 1H(;:_I havo no do'.o.t tl,at with your know!,,!-,., thoonticil 
 and practical, you will ,,i ,„- a new character to photo.-raphi,. ,,ortrailurc 
 
 I think the two great points to he attcn.icd to aro : I. The s„,allncss „( the 
 aperture of the. lens; and •.'. Th,. si.nplioity of the optical apparatus, the 
 smallcHt ih.cknesH of the r,.fra,.ting material, and tho .sn.allest t,uu,l,cr of 
 rclnieting surfaces. 
 
 1 <lo not think ./,.,r;, ,/r/inif,.,n at all necessary ; on tho contrary, 1 think it 
 an evil. 
 
 In society, I .s-.: lUees, and every e..Kpre,ssion upon then,, with sulliciei,t 
 d.8tn,ctne.ss. notvvith.standins my long-sighted vision. Wh. „ I p„t „n .^las.scs 
 to have perfect vi.sion, tho v.^ry di.stinct ,,ict„n., even of the vo,n,g"st an.l 
 smoothest fa.^e.s, is disagrnoahle, wl,il,.. il,at of middl. -a-ed an.l old persons 
 1.S stdl more .so. ]!ea,.ty either of fonn or e.x|>res.i,,„ is injured hv .sharpness 
 of oulhne, and the vision of minute parts, and the corrugations and winkles 
 of age, and even of middle life, are made douhly di.sagrecahle. 
 
 Has it ever oecurr.-.l to yo,i, that a large" lens perlV^cUy achro.na'.ic, and 
 w.thoul s,,henc,,l aherration, caimot give a correct representation even of a 
 liirJnUiijh:! s/iiic, siudi as tho hreadlh of n line I" 
 
 I shall he glad to read the papers you mention, which I hop,, will soon ho 
 |'i,hlished. 
 
 ./.■m 3, 1HG7. -I an, delighted with the result of tho topaz e.q,crin,ent • the 
 imrtra.t is sing,d,,rly line. The di.spcrsivo power of topaz is (I-(.'.>1, that of 
 crown gla.s.s hein,. OO.ri, and that of Hint glass ()-0i8. To h.avc the s.nallest 
 uherrat.on. the .side of th,. lens with its ll.atter surface shouhl ho nevt the 
 unage.the ah.rvatiun in (his ca.se heing 1, and the aherration in the other 
 case .(, .so that your ..Nc.llent clfc.t h.as he,.n ,,r.Hl„,.ed ,nth ,l,e /,n-,c^t „l..Tr.„h.u 
 'J h,s sccns (o throw a tew li.^ht on the suhj,.,-!, The lens had thus a gre.at 
 
 H 
 
IS 
 
 iicliroiuatic, T Iitnl to oi>cr,i1f with llic r<.<'iis .if llic cliomioal 
 rays, wliidi, liy invviDiis cxiKtriiiiciil. I liiid Inuiid to lie 
 (Miuiil 1.) ili(^ focus of nil olijcct ]ilac(Ml jit 'J I in. Iicliind the 
 ]ilaiii\ ^'iviiif^- a corivct visiiiil locus of ji iicrsoii placed at 
 I'Jft. licfovc tlic caiiii'i';i. The result was a, vi'i-y sliari) and 
 
 number of foci, a numljcr increased by the number of chromutic foci, iind 
 hiHcc thf ixcilliiin' vf the picturi'. It Li easy to incrcaso the numbur of foci 
 by increasing tbe size of the lens, but then you introduce the (;rror iuising 
 from the sujierposition of difl'ercnt views of the ligure as seen from dill'orent 
 points of the lens. 
 
 If theso views arc correct, it would bo worth while to try a lens oi Jliiit 
 (jhiss with various ehromatic and actinic foci, and with the radii of its surface 
 as 1 to G (a plano-convex nearly), luiving its flattest side towards the sitter. It 
 will be curious if wo find that the lens which i,s the worst for the telescope 
 and the mieroscope should be the ' st for taking the picture of a solid 
 object, surli as the human figure. * * » 
 
 I wish you would try some oxperinimts with the largest lens you have 
 in your cameras, 1,. id take five pictures of a large statue, oni! from half an 
 inch of its centre, one from the lowest point, one from tlio highest jiart of its 
 circumference, and on(; from its left and right. 'ITiis would show clearly 
 the eflect prouut-ed by tlio size of the lens. 
 
 If the experiment were made upon a living figure, the change of expression 
 would be seen. It would be also very interesting to take a photograph of 
 the same statue with a small [lin-holo. 
 
 f'-''^- — I will read tlie account of your focus C(iualiser. Vour paper on 
 the liinoeidar Thai.matroi)o is must interesting. The dispersive power of 
 diamond is ()-038. rock crystal ()-()2(i. 
 
 yhii/Nsf 7, 1807.— I am much interested both with the experimental and 
 hi.storical part of your last letter. 
 
 Your five experiments on Da'ltneyer's method of focus diffusion confute !<• 
 completely. 
 
 The experiments on Voigtlilnder's !ins with tlie (ixid and m.jvi'd feeus 
 prove the groat advantage of the luller, Ijut I slujuld have liked to ,'^ee the 
 effect of the central aju rturo a/one. and of the two extremes. Voigtliinder 
 with five holes beats Dallmoycr witli live holes, a!id your experiments with 
 the single Hint glass lens in the good and bad positions seems to refute my 
 theory of using, in photograiihy, a lens unlit for the t<ilescoi)c or microscope. 
 I recur, then, to the small topaz lens, and I am anxious you should try with 
 an ajierturu "f :i \ of !in inch, which will jjivc ;iliiiri,sl c(|nii] .listinclness to all 
 
1!) 
 
 • ■nn-cct iioTtirit. cvorv plnno ,,f lli,. Jin.,,,,. l,,.],,..- .(innllv vvll 
 'li'liiicil. 
 
 "Sir l>:iviil I'.nnvslcr \v;is nnicli i.lcus. ,1 witlt flic success 
 ot'lliiscxporiiiiciit, iiiid cimsidcviug tluil it wiis partly due f,, 
 the siiiiiU dispersive pi.wvr ,,1' roil- crystal, .su(;-gested that 1 
 sliduld now try a lens uftopa/, the disporsivu power of wlii, n 
 
 llie Inivos of your focimotro, ami 1,,, tho licst iiistrmmnt fur dei.tli (,f 
 focus. 
 
 Thus it is thcoroticiilly trun, for the ilcjith of focus increases as the aperture 
 diminishes. 
 
 If I ani risht in believing' that the numerous refractions, ami surface 
 retleetions, and thiekmss of glass, may allbet the ,..i,r,.siun „f thr hnwm 
 I'lia, then the siMf-lo I. us. of loa.st dispersion, and least abermtion, and least 
 tliiek-ni'.ss, is the most perfect of photo-raphic instruments, when the; ch.'mii al 
 process is sudlcicntly sensitive. 
 
 Am r right in suppo,sing that your foeimetre does not show tlu! elT.jet of 
 large lenses in widening the b-ad ; that is, in showing (or enlarging) the ears 
 wlicn they should bi^ eitlicr not .seen, or partly .seen '( 
 
 I hope you will be ablu to .show the results of your experiments at J)undee, 
 by means of the magic lantern. 
 
 Ah,iusI 20, ls(i7.—l cannot resist thaiddng you for your interesting letter 
 and its enclosures. 
 
 V(,ur portrait by the t<ipaz lens is i>,rfut. Nothing can surjiass it, and it 
 is hardly necessary for you to try the one-fourth of an inch aperture. It 
 might be worth while to try three-fourths of an inch, which will reduce more 
 than one-halt the time of sitting. 
 
 In trying either tlu! oui^fourth or three-fourths, however, the thickness of 
 the lens should be reduced to its mininmm, to remove whatever might be duo 
 to the mass of refnicting matt(T, or the im])erfeili.m of structure. Strictly 
 si.eaking, too, the face of tlu> lens should be pcrpeu'licular to one of the axes 
 of double refraction. P.oth Ih'se, however, are nearly inlinitesini.il in their 
 ellbets. 
 
 The portrait with \'..igtlander and two apertures proves the deleterious 
 intlueni'e of largo apertures. 
 
 I rather doubt your e.xplanatiiui of the bad efl'eet of aberr.ilions. 
 
 The images given by diinuvnt parts of a b ih ar(> mit " of .a dillerent 
 .size:" tliey are views of the same object from dil!( r.'ut jinints ,,f sight, and 
 they dilba- in si/.e only in so far as thiir size is aU'ec'.ed by the objict lieing 
 viewed from dillerent points. 
 
 It -2 
 
20 
 
 is still less lli;m lliiil nl' vnck crvstiil. Accoi'dinii'ly, I liutl a 
 lens (if tnjiiiz iiiinli', willi llic curves nf (I lo 7, f^nviug tlio loss 
 iimimnt nf s]ili('i'ic;il ulicriiilion, so lliat 1li(> rosult was slill 
 ninn> MLrprisiiiu'ly hcnuliriil tliiiii lli;it olifaincil \silli ili(> 
 iliilililc cmiNrN iMik cry.-tlll liiin." 
 
 "ill nnliT to pl'dNC till' (Iri'icls nl' 0])('V;itil!;i' With ]l\V'j:(' 
 
 aportuivs in lenses, I ojiei'iited in the fnlluwiu^' luauiier : — 
 "I had a ilise of thi> same size as the h.'iis (-nn.), liavine' on 
 its diameter an aiierluro ol' lin., which oould at will hetnrned 
 altei'iiatcly to +ho rij^'lit or left of the horizontal line cori'es- 
 pondinp' with the diameter of the lens. iiaviiie' taken a 
 portrait with the a])erluro on nno side, the diaphragm was 
 tnrned so as to jiresent the opening on the other side, and 
 then a socoud portrait was taken liel'ore the sitter had 
 moved." 
 
 " Tho result of this experiment is very oonelusivo, for the 
 two portraits being examineil with a stereoscope, present the 
 strongest stereoscopic effect which can he obtained by the 
 usual mode of operating." 
 
 In 1801, Claudet set up a Temple to I'hotography alter 
 his 0W71 heart. Here, in the Hall of Audience, could he be 
 cousidted !it call i'rom ihcti'/i/fiiii/ siair/inii. Here, surrovmded 
 liy symbols and examjiles, the neojiliyte was imjiri'ssed with 
 the dignity and lieauly of ]iliotogra]hy : ]ierhii]is lii'st learned 
 that pihotograjih}' is an oulcome of Ihe labours of philosojihers 
 through tho ages of (ivilisation. l"\ir he s;i\v, on glancing 
 at the nie(lallion portraits arouml the co\-e, names of men 
 now thought of as ancients — Roger liacon, Porta, Da Vinci, 
 Newton — and was remind, 'd of (he honour due to imuiy 
 neai'or to liis own time, as Davy, Wedgwood, Niepce^ 
 Daguerre, l^dbot, AN'healstone, I'lewster, .Xi'ago. H(! saw 
 
'Jl 
 
 (li'SorilxMl liy allcydrifal pniiitinp's tlu' prdgivss nf thi' mis liy 
 wliicli iinliiriil (il)j('cls nml tlx' liuiiifin tunii liiiv.' ln'cn ivjnv- 
 
 soiitcil fViiiii ll iirlicsl tini" — stiituiiiT, ]iiiiii(in2', .'iiiiiliciilinu 
 
 (if the (•iiiiii'i'a nl)sciir,'i to pli(it!)grapliy, and ol' jiholnui'iqiiiv 
 to ili(> stcn'osciijM', ciiililciiis of Ili(> (liscDVcry of ]ili(ituL;-i'a]jliy 
 anil of till' means of pi'odncinii' pliotooTiipliic jiicturcs, nnii'al 
 scrolls, cIuMnolo^-ical I'd'urds of I he iiiviailionsand discdvcrii's 
 Avlii'ivinito pliotogTapliy is indelili'd. ())•, loukinn- ai;-ain, 1h' 
 read inscriptions of llic classic (est iniony n\' Vii'Ljil nr ^Madial ; 
 " Xilll'l rrciirilKiih hi.r r\/ i iniriihi ^ S<ilf:ii i/iii^ ilitci-c InUum 
 iliiil(<il .'" '• Lii.r IS/' iiiiiiiili hiiitcn.'''' All this is to l)i; seen 
 no niniv. This Tenijile, so ehaiaeti'ristic of ( 'laudel's devo- 
 tion to photoo'vaphy, was Imrnf a 'i^-w weeks alter its chief 
 priest had (piitted it for ever. With it were lost many 
 lieantlful \\oi'ks and valnable relics of the master's 
 laliours. 
 
 I'.iit. as we ]i;iv(.' elsewlion; said, that for which ( 'iaiidel 
 
 deserves liest jo he J-eniendier 'd, is of sneh a fdjric as liro 
 
 caunol desti'oy. i|i' has lelt his imju'ess upon siaence — a 
 t^-ap in till' ranks, l.ike all men of oi'l^'iniil tlioni:lil, lie will 
 lie followed, not ivplai'cd. 'f'hose who hannt the i^roves of 
 •science will miss his familiar form, and listen in \ain {'■>v 
 liis in.-triictive Incnhi'ations. For he was of the order of the 
 re.'i]iatctics. Whether at the jjoyal Society or at jihoto- 
 eraphic confeiha'ations in l']n,i;Iand or Scotlaml, or at universal 
 i^liihitions — whi'resoever the JSritish Association wandered, 
 there was he seen and heanl. Or whether in the rjii/n- 
 siipliiviil Ti'iiiisdi-liiiiis, or in tlie ('diiijiIcs Itinihix^ or in plioto- 
 graphic jonrnals, or in art jonriials — wherever pi lotoeraphy 
 liad to he expounded or vindicated, there woidd bo i'onnd 
 
^mmmm 
 
 llii' j'rddud nf Ills |icii, lli> activitv \vii> iiiccssanl, his 
 iiiiiltd tliat III' Pascal : " /,, ,vy/(/s- c'r.v/ /a i,,nrf.'' 
 
 Niir Wdiilil \vc (diicliuli' a mciiinir nl' ('laiidct willunil 
 huliratioii (.r his jM-i'sonal i|ualilirs. Tliat he was ol' a 
 i;viu'r()us Iciiijicraiiicnl. lilinal and ;:ciiial, is indeed pai-tly 
 iiiililieil l)y wliat has lieeii ]a'eviiaisly said of liis euthiisidsin. 
 it wasso. He was ''(.tieot'naiiire's j;'entleineii." Taisordid, 
 ho allowed tlie interests of soionee to overrnle all meaner 
 considerations, and with the true senfiinent of Ihi' jihilo- 
 sojiliei'. suhdued all thing's to t]i<' ])nr]i(ise of invest i,L:-at in Li- 
 the reeondile ]irinei]iles of nature's laws. This was liis 
 adoraliou: — " A'v/ 7Av(x in iiuhi.^, est J)r,i.s in /v/z/rv." AVhaf- 
 t'Ver his toils or his disajipoinlnvnts, he was not diseouraLivd. 
 "lie tliat seeketli to he enu'iient aniin^'st, aide nieii Iiath a 
 ti'i'eat task," says I'.aeon, and with such a task ('laiidet was 
 contented. He was one who had set himself to answer the 
 iusatiiite Sphinx, not exjiectinji; the succ(\ss lA' (Edipus, 
 willing to die in the enci)unler. h'oi' vith. him it was truly 
 a " lahour of love." Science was the mistress of his heart, a 
 sweet echo vwv responsive to iiis <'onstant call. And s<p he 
 (ouiiil solace in — 
 
 " Divine I'hilosophy, 
 Not hiirsli iuiil L-rabbod iia dull fuol.i Huiiposc, 
 Ikil musical as is Apollo's lute, 
 And a licrpetual ivnat of nnctarod sweets, 
 Where no erudo surfeit riui,'ii,s." 
 
 The recognition of Clau(h't's merits in his lifetime was 
 ]ierha]is sulli(,'ient to satisfy a man who sought only such 
 honour. He receivi^d awards of eleven medals, including;' the 
 Comu'il Medal of the I'ldver.sal lv\hilutum, ISO I, besides 
 
^F" 
 
 ■■ 
 
 that oil fiflicr groat .icoasions, being on juries, lir wasoxeluilcil 
 from llic a\va,r(ls. lie was elected Mi'iiiltcr of tlu' Royal 
 f^ociclyiu I^.V,, mid in ISO.'), lie was made a Chevalier of 
 tlu! Legion of iioiioiir. Hut of sueh was iio( his ainltition. 
 1 fe was a votary to .seieiH'c, mid wrought ehielly to feed h(;r 
 ultai'-llamc. For him thai was enou'j'h. 
 
 Reel (J I'llrh /((■/■■i.sr Iiic/'VC'< ('•'>/." 
 
IP 
 
•.'•") 
 
 I 
 
 Al'I'ENDIX. 
 
 SCI KNTi I'll" I' An: IIS 
 
 in 
 
 A. CLAUDI^yr, F.K.S., 
 
 ^MI.WlMi MIS PUINCII'M. |i|s(;<)Vi:icll> AND KLsi: MICll Ks |s 
 l'l|ii|ii(;KArilV, K'lT. 
 
 Oil ii iii'W iiiucrss i(ir iic'coleratiii"- tlu' imMliK'- „ , '^'' 
 
 ' ~ 1 l;t;iil hi-liiir t |u 
 
 tiiiii(»r till' iiiuij;v on llu' I)agiiorronty|)c iiluti' 1>v '*">■''••"'"'> 
 llii' iidilitioii ol' luMiiiiili' ami clilDiMdc nl' inilint' {<< 
 the ioilidi' iif silvi'r. Unyiil Sdcicfy, Jimc Idtli, 
 IS H. —/'////. JA/.'/.. vol. xix., p. 1()7, 
 
 On the uiiu-i'oincidfiicc of the locus of the Uiii.i liVim.. iii.' 
 liliotog(,'iuc rays with tliat ot tiio \isual rays of 
 till* solar s[i('ctriiiu, — Prm-. Jim/. Sor., vol. v., ]>. 
 ')l'-i; Annlninr di-x Sciniccs, May. ISJI; /'////, 
 JJ>/i/., Novcmbor, 1S4!>. 
 
 1 >cs aclioiis ijiic \r> ijivcrsos radiations .sulaircs 
 <'.\er(M'iit sur los couclics iTiodiirc, dc clilorurc on do 
 lironmrc d'aruvut. — ('(iiujili.-^ Ji'in'/ns, t. \.\v., pp. 
 
 IMT 
 
 1 
 
 d 9 T f" '^ 
 
 ± Kj li U ^ 
 
2V> 
 
 Sur ractiuii (■liiiiii(|U(' dcs dillt'i'i'iits raVdiis dii 
 s]M'cti't' siiliiirc. — ('{iiiijili's lii'iuhis^ \, \\v., ]n>. ;!mS, 
 !>10. 
 
 1. I 'i*"J'.. .1 ^*i' <lii' diirci't'iit iiroiicrtics of sulur mdiatiitii 
 ti'.jll,'^').vi;mr''' 1'1'oduciiig or iirovciiiiii}:: a d<'ji()sif of nicrcurv on 
 silver ]ilat('s coaled wiiii iodine, or its coniiiounds 
 with lironiine or chlorine, modified liy coloiui d 
 gluHS media, and the atmospheic — /'////. 7'/vo/v., 
 ISI7, ]ip. -JVi. 'Jll-J ; /;/•//. As.sor. h'r/,. 1M7, part 
 ii., pp. ;!■">, ;!7 ; .tin'. </r Cliiin. rl (Ir I'lii/s., IS IS. 
 1. xxii., pp. .■!;{-J, •Jod; /'////. Md'j. |S}S, v.-l. 
 wxii. pp. SS, !)S ; Ziliilrilcscln ^liiii. /-'/.v., iS|'.), 
 
 Vol. 1., p]). 'J.")7. -iT-K 
 
 On the proi.frcss of ])liotoi;'rM]»h\'. — Tiiiii.-<. Soc 
 Arts, Ku]). vol., ]i. l!)(). 
 
 It. n.\ Mill' til.- "" ^'"' ii''1'"'i "f ^1"' re(l, oranjit', and yellow 
 ti..ii, .■<wiui-ii. rays Upon iodised iiud liromo-iodi.-~ed siKcr plate> 
 after they lunc heeii uifected liy daylit;li1. and 
 •Alier phenomena of photoij'raiihy. J'/ii/. J/hi/., 
 ISIS, vol. .\xxii.. J). !!>!»; Jirif. Ass,,,-. Rrp., IS-IS, 
 part ii., p. od. 
 
 On the IMiotoj^raplionieter, an instrument for 
 inoasurinj? the intensHN (if the chemical action of 
 the rays of liiilit on all pliotn^rapliic pn'iiarations, 
 and for compariii;^- with eaih other the Sen>itive- 
 ness of the.se dilferent pre[iaratioiis. — /*////. J/a;/., 
 iStS, vol. xxxiii., p. ;Ci!». 
 
 , , i"'," , liesoarches on the thoorv of the iirinciiial 
 
 Ki.Kl bi-loiv till •' i I 
 
 Sl~'!iirmiiTii'-'' I'ti'^nomena ol i)hoto<.'raphy in the nafiucrreotv] 
 
 lium. 
 
 lO 
 
'47 
 
 lu'occss. — /</•//. yj.v.vw. Jic/t., I.S|!), ])ai't ii., pp. •'!•"), 
 ;'.<;; J'/n'/. Mwj, Is I!), vol. xxw,, p. 'M \. 
 
 On the Dviiaotinoiuotor, an insli'unii'iit Inr i,"'"' 
 
 mciisuriiij.;' tlic intensity nt' tlic ]iliiitn;j;viiic rays i',',J[|'[|4i\\j,7,','.jt'|',; 
 and coniiiarinjjf tlic jjowcr ul' iiliii'i't-j^'lasscs, witli 
 ()l)sei'vati()ns on fill' (lill'fiM'iicc lidwccn tlu) visual 
 and l*lii)l()<^('ni(' Foci, ami tlu'ir constant variation. 
 
 — />'/•//. J.s.Nor. y.'-y/., IS.V), p. l-j; /'////. JA'y., 
 IS.")!, vol. i., y. i:s. 
 
 On tlio danjxprs of tho nu'ivuvial vapours in tlio , '■'■'i 
 
 " ' HriJ.l I„.||||V Ihl 
 
 1 )a<,ni('iT('oty]ic ])r()coss and t he means to ol)viato tin' ,',''!|!,'"i'|,,'vivif ''' 
 same. — Jiril. ^■i-s.soc licji., 1S.">|, pjirt ii., jip. H, t->. 
 
 Oil till' u-^c ot a I'olyi^'on 1o aseei'tain tln' 
 intensity of tin* lif^'lit at dillevont angles in tlic 
 pliotog'i'apliii' I'oo'jii. — Jtn'f. Assor. J{i/)., lS."Jl, 
 ]»art ii., y. I J. 
 
 Nouvclles reelierelics sur la differcnci' entrc Ics 
 lovers visuels et ))liotog'eni(|ues, ct sur leur con- 
 stantc variation. Paris. 
 
 On tho Sterooseononieter, and on a manit'old i>'^ 
 
 Iiinocular caniora. — Jin'/. Assoc, licp., 1S5'.2, ii. (i. li'"'"'; ,;''-;""•'• 
 
 On the an":le to !•" mveii to hinocular iilioto- , , ''•'i'- 
 
 " ~ ^ Ki'.mI lii'lcri' till 
 
 ■I'raphic pictures for the stereoscojn'. — liril. Assoc, 'i",',"]'!,,^''"""'' 
 Ilc/i., lS->''5, i)art ii., p. 1. 
 
 Le stereo.scopc it ses applications a la ])hoto- 
 g'raphie. (Extrait d' un Memoire In it la t^ociete dos 
 Arts do Jjondiv.-s Ic III .lanv., IS.VJ^ ct pour li'(jU(.d 
 
!iS 
 
 .|c S.rll l'lV>il|r||1, S. A. l;. I.' I'lilKI' AIImiI.) 
 
 I'liris, Lci'diiiiir- I't S('i'ict;iii. i>|itii-i('iis dc 1" l'".iii 
 iicrcur. — Sor. Arts .Innr., \nl. i., |i. i'T. 
 
 ( »ii till' iiitri"liiclinii ol' luiTciU'iiil v.'i]ioui' intn 
 
 lllc CIIIIICI':! Ill 1 •ilL;'IH'riC(it_Vl'y. — I'/m/n. Sur. ■linn-., 
 |S:, I, yy. 117, l|!l. 
 
 li.'.i.l hirurc II 
 
 1 
 
 Oti tlio l'ulyst('r('iisco]ilic(iii, nn iiisfniini-iif wit 
 ti'iiI'''uiaV.l!«-'''' iii''i'1i!»iiii'iil iii'niiij>'('inciits, liy wliicli iikiiiv stcn 
 
 scojiic! pii'lurcs ciiii lie successively eluiiigeil iiiul 
 examiued sit oiice by six jicrsmis. 
 
 injii. (Ill variniis ]i|i('iiiiiuen;i nf relViictinn llirnii^li 
 
 iiiiiisii As.„.ia. si'iiu-leiisi'S 111' iirisms iirnduciiii'' iiiininiihes in tlie 
 
 tiuii, eiiciuii- _ _ ' . . 
 
 •'■""■ illusion nl' stereiiscojiic iiiia^'es, — I'ruc. /I'm/. Sm-., 
 
 vol. viii., ]i]). ill I, I Id; /;,//. ./x.vor. /:,/,., \s:,t\, 
 
 jiart ii., yy. !', I"; P/n7. J/n;/., IS.') 7, vol. xiii., ji. 
 
 71. 
 
 l;,ii,ii»ri;. 
 
 iHlnri' 111.' 
 
 lioviU Suciely. 
 
 (»:i tlie ]i;K'nomonon of relief of llie ima^'e 
 I'onued i n t'io Li'l'ound p,'lass ni' tln' camera uliM-ura. 
 — I'hji: y,'.///. N'/r., vol. viii., ]>y. ofil', •')7'i ; /'////. 
 Mil;/., 180S, \dl. XV., y. •)l)7 ; I'/in/n. ,Soi\ .limr., 
 180S, ],],. I'.' I, \H\. 
 
 ivw. On the Stereoiuoiioscojie, a new instrument liv 
 
 fu.l«l lii't'urr Ilk' 
 
 Ko.viii sufiity. Avliieli ail u[i])arently sinj;l(! ]iietiir(; jirodiices the 
 stcrooscopie illusion. — /'/v/r. 7i'e//. Sm-., \(>1. ix., jip. 
 r.jl, lIMi; Phil. Minj., IS.JS, vol. wi., y. KI'J. 
 
 i«M On the stcreoscoiiic anjile, \.f. ; on tlio stereo- 
 
 n'nn' AiinX'cn'' nioii'''i'L'r>po ; on tlio focus of oliject ^'lasses; on a 
 
20 
 
 I'liiuift'iiij? (li(i)ilirnu'iii I'nr ddulilc acIii'Diiinllc ciiii- 
 liiniiliuns. — A'/vV. ./.vvor. A'//;., |s.-|l), p. {>•>, 
 
 riidtof^Tiililiy ill ils rcliiliona to llic fliii- iirls. 
 All cssuy ivinl M;iy (i, iSdO. licfon,. tlic riintu- 
 f'Tiipllir Siicirty of Scntlilinl on llio im'cusImii dl' 
 llii' aullinr's cli'diiiii lis II iiiciulji'i' n[' till' Sdcii'ty. — 
 J'/io/i). Soi: Jniir., .luiH', I sou. 
 
 Oil till' iiriiicijilcs of llic solar cimu'ra. — /In'/, n,.;,,] 'i!!"?,,.,' ii„> 
 -Is-wr'. Iii'/K, l.S()(>, part ii., lip. (i'J, ((•'> ; I'/io/o, .b'w, ti'.n,'\)xr„ni', 
 'four., IS(il), pp. USS, L'SI>. 
 
 On llio moans of increasing the mv^h of liiiio- 
 cular iiistnuuoiits in order to obtain a stereocnspin 
 clfcct in jiroportion to their niagnilyiiig power. — 
 Ilri/. ^Is.wc. Hep., ISGD, part ii., pp. (51, O",*. 
 
 On flic laws which rec'iilale Ihe cnnjn^-ate (iici '■*"'• 
 
 ami the .sizes and jiroiiortion of images according 
 to the distance of cilijccts. New method for eoni- 
 piiting all these various measurements, — I'/iv/o. 
 .S'r-e. Join:, iS(il, pp. l;j:5, 1:;!). 
 
 On the means of following the small division of ^^,^,, 'iJ"?;,,,, „„. 
 the scale regulating the distances and enlargeinent li.VulV.imi.naL-f. 
 in the solar camera. — Ili-if. vissw. lie/)., iS(J'2, p. 
 IS. 
 
 On the (iiicstion of a separate exhihition of i;''"<';'spi'iii'; 
 liliotography as an aiuu'X to the International ■'"'""■''• 
 Kxhihitioii of iS(L\ ADirch lo, y. o. The New 
 I'ictiiiv (ialleries, April, [k '■'>'■'>. J'hdargeinent of 
 photographs, June, p. ('>2, and July, ji. DL 
 
30 
 
 >> 
 
 iinjHt '"'L. ti„. '^'"' ''^^■''i' <'ln'oiiiatosc(ipo, nii iiistninir.iit to 
 'i"»r.Nv«vHX" *'>''''"iii"H.' niid coriiimro tlic rays (pI'IIi,. sfnrw.— //r//. 
 Asm: liCjK, 1S(J;{, p. ,"). 
 
 On sdinc ]ili(']i(mu'!ia imxlucod hy tlic ivfVacfiM' 
 
 l^WToftlic (-jr.— 7V///. J%., iSd'!, V,,]. x.xvi.. ],. 
 324 ; Coiiijifcs Jtcii'.lius, t. Iviii., i>. N!>. 
 
 ISfil, 
 Krn.l tirlcro (lio 
 Uriti-li AskuciM- 
 'imi, llatli. 
 
 On riioto-souliihiro.— /;/■//. Assuv. 7Ayj., IHd), 
 ]». 10; 7VWo. ,S'w. J„m:, l,S(i}, April l;-) .-n,,] 
 October 15, pp. ]<), i)\ 
 
 lA 
 
 u™.n,c.i„ro ti.o ^-"i iiiovnifi- pJiotooT:i]iluo tl^niros, illustraiino. 
 
 tiyn, liin.ani;-' somo ]ilu'noniona of virion ooinirctcd witli t]i.> 
 oonilnnation of tlic st<w.sco],.. and lli,. p],, imkis- 
 tf)seopo l.y means of photograjiliy.— 7'/,//. J/,,,/., 
 lS()."i, vol. XXX., p. 271; Brit. A.s.or. J^vj,. \X[\:,. 
 P.O. 
 
 On storooscopir phenakistoscopj-.— 7V/oA/. Jam:, 
 November IC, iSfi."), j,. 189. 
 
 ^vm,i M.'Vo tho Optios of pliotojjraiiliy on a now jiroeoss, for 
 ti^rxJumr' oqualisingtho deenition of all (lio planes of a solid 
 
 fifi'ure roin'osented in a i.liotooTMpliIe pictun 
 
 moans of obtaining harmonious and artistic ])or- 
 traits.— /;/■//. As.o,: 7.',y;., iSfiO, p. ;) ; 7./,//. j/,,,/^ 
 1M()G, vol. xxxii., p. 2I'J. 
 
 \ 
 
 % 
 
 On photograpliy as an art.— 7V/(//r;. Six: Jmtr 
 1SG(>, p. 2W. 
 
 Tlio " Gazette doK Beaux Ai-ts" oil plioiograpliy, 
 January, J(i, isdd. p. 2 H. 
 
31 
 
 % 
 
 Oil !i now i'lici^ rcliiHiig to Imioonlar vision. 
 J'i'iic. lioji. Siir., vol. xv., p. 424. 
 
 IHI)?. 
 lii'ii.l h.i-in- til,' 
 
 Oiitii's 1)1' iili()t(inTii])liy : on a .self-aetiuff focus- i!<.i'i iiffiro tiic 
 equaliser, or tlio moans of producing the (Uiroron- 
 tial niovoniout of tl>e two louses of a photographic 
 optical c(jnibInatiou, wliich is ca])alilo, during the 
 ox]i(>sure, of bringing iiU the ]ilanos of a solid 
 tiguro into focus, without altering the size of the 
 various images superposed. — Proc. Itotj. Soc, vol. 
 XV., [). 4-;(J. 
 
 On iihotographic portraits obtained by sinjrlo "*' 
 
 Itnises of rock crystal and topa". 
 
 S07. 
 bro thr 
 Uriti-^li .\<s(M-i.'i- 
 tioii, Uuiiilii'. 
 
 Ou tlie iiroduction of natm-al coloiu'S bv iihot(^- Ait,i„nnni. 
 
 •• ' IHi;;. 
 
 grai)hy, January, ]). 4; ph^'siology of binocular 
 
 vision — stereoscopic and pseudoscoinc illusions, 
 
 February, p. 40 ; physiology of binocular vision, 
 
 Jlarch, p. 7'"} ; I'hotosciagraphy — on the art (jf 
 
 painting ])ortraits, only from the shadow of the 
 
 ]iIiotograph projected on Oie ordinary canvas or 
 
 pajior, while the artist is at work. Description of 
 
 Itrucess invented by A. Claudot, May, p. 128. 
 
'&^ 
 
 ('0-\rMrXl('\TI(iXS FMTF.S \ I, A SdCIKTK FliAXCAlSK 
 1)K IMIOTdCl-'AI'IlIF, I'AI! M. Cl.AFDl'.T. 
 
 Alrthoile criirliograiiliii.' siir pnrccluiiu:. Vol i- ,,.■!• 
 
 Siir 111 vaiiiition Jc8 i'oyi rs (liuia lea Icntillcs. \'' ... , 
 
 l.'i'cliiiiiati'in (li^ iiriniilr a iiropos ilcs slrn'tiscui ilr M. IIiTiiwa:!..*, 
 
 Veil, iv., I'. SC. 
 I',l)rciiv(> oIpUiuio pemliint I'lclipsii Je IS.kS. Vol. iv., p. 00. 
 Strri'Otnonosroiifi. Vol. iv., p. 'i.").'). 
 Sur la (iiiistructioii du stcn'o.-icopo (n'pon.si' a Mr. lli ^lla;;i.s^. Vol. v., 
 
 p. ;).') et 1)7. 
 Sur lo primipci dc; la clLaniln'o solaiiv di; JI. Wcjodwanl. Vol. vi., pai^o 'J !'■'. 
 Do.s rapports do la I'hotof^r.ipliic avcc lo.s lioaiix-urls, Vol. vi., )). ■JCi.'i. 
 Snr lo moyon d'ai^ranilir I'an^lo dos iii>tniiiii iit.-il'iiio<.ul!iircs. \'ol. \i., )). -7.'^. 
 Olisirvati.ins surl'cmploi do l:i I'hamljro solairo di^ Woo.hvard. Vol. vii., p. :!. 
 Siir !o.s travaux jirimitifs do M. liayard. Vol. vii., p. I'.i. 
 observation sur I'emploi do la ch.'imlm^ sidairo. Vol. vii., ]). .SO, 
 Ijuploi do I'acido Curiuiiiuc pour aoiioitro ractiou phutographi ; V"' 
 
 viii., p. 'J'.;!. 
 Sur I'aLjrandi.ssi.'incnt dos oprouvos p1iotou;rapliii|Uos. Vol. viii , p. '22!'. 
 Kuiploi d't'crans moliilos. Vol. viii., ]i. Dili. 
 
 .\pplication do La Photo;;rai)hii! au )iliot\akislo('opo. Vol. xi., pp. 2S(1 i-l .l'XI. 
 I'hotoplasto^raphio; ii(mvra\i proc rdo do iilh.tosi'ulptiiro. Vol. \i., j.p. S.S ot ll'.l. 
 Sur un nouv':au jirofodo pour dimiior iiuo ogalo nottoto i\ tous U'n plans 
 
 d'un corps aulidc ropro.sonto dans iinc oprouvo photo;j:raphiiiu('. Vol. xii,, 
 
 p. 22.). 
 Fprouvos a rapp\ii ; olisorvations ilivorsos. Vol. xii., p. 2S2. 
 ()lijoctil'('ij[alisat(jur di'i» oiycrs. \'ol. xiii., p. 1 111. 
 Kmploi d'ol/jootifs on piorros prt'ciouMS. Vol. xiii., ]). ' o'.. 
 
■I