"^ > IMAGE EVALUATION TEST TARGET (MT-3) V. ^ {/ ^ .-A^ y. f/. 1.0 I.I li^ lM |2.5 if Bi£ IIIIIIO 1.8 IpS III 1.4 1.6 «< 6" ► p% ^J ^^ ^y^ ^ % '/ z;^ Hiotographic Sciences Corporation 33 WIST MAIN STRUT WHSTIR.N.Y. MlitO (716) •72-4S03 ^ iV y ^^ :\ \ .•"V* 4^^^*. V"^^ V o^ CIHM/ICMH Microfiche Series. CIHM/ICMH Collection de microfiches. Canadian Inttituta for Historical IMicroroproductions Institut Canadian da microraproductions hittoriquas 1980 Technical and Bibliographic Notat/Notaa tachniquas at bibliographiquaa Tha Instituta ha* attamptad to obtain tha bast original copy availabia for filming. Faaturas of this copy which may ba bibliographically uniqua, which may altar any of the imagas in tha raproduction, or which may significantly changa tha usual mathod of filming, ara chackad balow. 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L'exemplaire film* fut reproduit grAce h la * gAnAroaitA da: D. B. Wtldon Library University of Wtttarn Ontario Lea imagea auivantea ont AtA reproduitea avec le plua grand aoin, compte tenu de la condition at da la nettetA de rexemplaira filmA. et en conformity avec lea conditiona du contrat da filmage. Original copiea in printed paper covera are filmed beginning with the front cover and ending on the laat page with a printed or illuatrated imprea- aion, or the back cover when appropriate. All other original copiea are filmed beginning on the f irat page with a printed or illuatrated imprea- aion. and ending on the laat page with a printed or illuatrated impreaaion. Lea exemplairea origlnaux dont la couverture en papier eat imprimAe aont filmAa en commen^ant par le premier plat et en terminant aoit par la darnlAre page qui comporte une empreinte d'impreaaion ou d'iliuatration, aoit par le aecond plat, aelon le caa. Tout lea autrea exemplairea originaux aont filmAa en commenpant par la pramlAre page qui comporte une empreinte d'impreaaion ou d'iliuatration et en terminant pa- le dernlAre page qui comporte une telle empreinte. The laat recorded frame on each microfiche ahall contain the aymboi —»>( meaning "CON- TINUED' ), or the aymboi V (meaning "END"), whichever applies. Un dea aymbolea auivanta apparaltra sur la dernlAre image de cheque microfiche, seion le caa: le aymbole —^ signifie "A SUIVRE", ie aymbole V signifie "FIN". Mapa, |.^l«^~ * ch«rts, !c., may be filmed at different r < -stion ratioa. Thoae too large to be entirely inclu«.3d In ortlioim,| Wnrtmanii,§ Janiiiar,|| Joulclf Laliordc,** Lt'gat,tt Rt'iH.lt l*oggeii(lorfr,§§ Du Moncel,|||| Dele- zenne,1[ir mu\ otliers.*** 2. In the autumn of 1H74, T discovered that the sounds emitted by an elect ro-mngnct under the influence of a discontinuous current of electricity are not dui; wholly to sudden changes in the magnetic con- dition of the iron core (as heretofore supposed), but that a portion of the uftect resulta from vibrations in the insulated copper-wires comivosing the coils. An electro-magnet was arranged upon circuit with an in- strument for interrupting the current, — the rheotome being placed in a distant room, so as to avoid interference with the experiment. Upon applying the ear to the magnet, a musical note was clearly per- ceived, and the sound pc^rsisted after the iron core had been removed. It was then much feebler in intensity, but was otherwise unchangitd, — the curious crackling noise accompanying the sound being well marked. # The effect may probably be explained by the attraction of the coils of the wire for one auotlier during the passage of the galvanic current, * MalUHcri. Inst., 1845. p. 316; Arch, dc I'tlectr., V., 889. t GuilUmin. Ccjinp. Rt'nil., XXII., p. 2G4 ; Inst., 184G, p. 30; Arch. d. Sc. Phys. (2il scrk'g), I., p. I'Jl. X G. W'-rlfwlm. Comp. Rend., XXII., pp. 330, 544; Inst, 1846, pp. 65, 100; Poptf Ann., LXVIII.p. 140; Comp. Hend.. XXVI., p. 506; Inst, 1848, p. 142; Ann. de Cliini. et de Pliy.s., XXIII., p. :502; Arcli. d. Sc. Phys. et Nat, VIII., p. 20(5; Vofig. Ann., LXXVII., p. 43; Hcrl. Her., IV., p. 121. § A7/V W'lirtiiiaun. Comp. Rend., XXII., p. 544; Phil. iVlag. (3d series), XXVIII., p. 644 ; Arcli. d. Sc. Piiys. et Nut. (2d series), I., p. 419; Inst., 1840, p. 290; Monatsclier. d. Rerl. Akad., 1846, p. 111. II Jmtnlar. Comp. Rend., XXIII., p. 819; Inst., 1846, p. 269; Arch. d. Sc. Phys. et Nat. (2d series), II., p. 394. 1[ ./. /'. Joule. Pl.il. Mag., XXV., pp. 76, 225 ; Berl. Ber., III., p. 489. •* Lalwde. Comp. Rend., L., p. 692 ; Cosmos, XVII., p. 514. tt Leifat. Brix. Z. S., IX., p. 125. n IMx. " Tolephonie-." Polytechnic Journ , CLXVIil., p. 185; Bottger's Notizl.l., 1863, No. 6. §§ ./. C. Pore. Procecilings of Hoynl Society, XII., p. 217. II l\uie. " Vibration of Tri'velyaii's burs by tiie galvanic current." Silli» roan's Journal, 1H50, IX., pp. 106-108. \ G PKOCKKDINCS OK THB AMBIUCAN ACADEMY ' ( "I * »■ currents iii illicit wiics of :i Hulinikortf'H coil, iiiul the tine wircH were connected with two -strips of hr.iss (A and H), insulated from oiio another l»v uieaus of a sheet of |ia|>er. V\hu\ phicii.;? the ear »<;.iiiist one of the strips of hra-^s, ii s(»uud was |)ereeivt'd like that (leseriliejl uli(»v»' as proceedinjf from an empty helix of wire during the |»assa<,'e of an intermittent voltni<; current. A similar sound, oidy mu<-h moro inti-nse, was (>mitted hy a tin-foil condenser when cunn<-cted with the tint! wires of the coil. One of the strips (»f bniHs. A (mentioned iiljove), was held closely a<;ainst the ear. A loud sound cnmc! from A whenever the slip \\ was touched with the other hand. It is douhtfnl in all thes(> cases whether the sounds proc'eeded from the metals or from the imperfect conductors intciposed between them. Further experiments seem to favor the hitter supposition. The strips of brass A and H w(U'e held one in each hand. TIk; induced currents occasioned a muscular tremor in the liiij^t I's. I 'poll placinj; my forefin;ier to my ear ji loud crackliii was then dis- tinctly conscious of a noise (which I was umilde to perceive) proceed- \i\f luch inoro <) with the •111 I'loHcly slip i^ wiH ICS wlu'tlltT wmliu't^^i''* , favor tlu> Olio ill t'lu'li nior ill tlio I'kliiijj noise , A frioml iiothiiif?- I ftB then . When a voltaic battery is common to two closed circuits, the current is divi(h'il between them. If one of the circuits is rapidly opened and closed, a pulsatory action of the current is occasioned upon the other. All the aiiilible etTects resulting from the passage! of an intermittent current can also be produced, though in less degree, by means of a pnlsatory current. lU. When a permanent magnet is caused to vibrate in front of the pole of an electro-magnet, an undiilatory or oscillatory current x|)(>riiii(>iitiil room, and tliu other takuti to thu luiHOiUfiit of a:i atljoiiiiiiir liniiHt'. l.'|Hiii Hiii;,'iii^ into i\w l«'I('|tIion<», llic toncn of tlm voice \v<'ro ro- produt'ctl Ity th«- inHtrnnit^nt in lli«! dixtant room. Wlit-n two pcrHonH Hang HinudtancouHly into thu iiiHtrun)t>nt, two nol«>M w(>n> uniittcd Niniul- tancoiisly liy tlio Iflcphon*' in th«; other house. A friend wiih sent into tilt adjoinin;; l)tiildin!{ to noti; tlie etf'cct prtMhieed l)y arlindato speech. I phicetl tliu nieinl>rane of tiie teleplione near my moiitli, and uttered tlio Kcutenot), "Do yoii understantl what I say?" iVesentiy an answer was returned tlirou<;h the iiiHtrument in my liand. Artieu- hile woihIh proceeded from the clocli-xjirin}; atta<-lied to llie memhranu, and I iieard the 8enten<'e : " Ych ; I understand yon perfectly." Tlio articulation was somewliat mutlietl and indistinct, altliou;r|i in this ca-MO il was intellirane. The elementary sounds of the Knglish laiigiiiige were uttered sm*- cessively into one of the telephones and the ettects noteil at the (tther. C'onsommtal sounds, with the exception (»f Fj and M, wi're unre<'og- ni/ahle. Vowel-Kounds in most cases were w (in now), i>i/ (in hoy), our (in poor), out' (in door), ere (in here), ere (in there), were well marked. Triphthongal vowels, stjch as ire (in fire), our (in flour), oicer (in mower), ni/) r (in player), were also distinct. Of the elementary vowel-sounds, the most distinct wcr«! those which had the largest oral apertures. Such were a (In fur), aw (in law), a (in man), and e (in men). 1.'5. Electricjd utidulations can be produced directly in the voltaic current by vibrating the conducting wire in a licpiid of high resistance included in the circuit. The stem of a tuning-fork wjis comiected with a wire leading to one of the telephones described in the preceding paragraph. While the tuning-fork w;i8 in vibration, the end of one oi" the prongs was dipped OF ARTS AND BCIENCES. it of ilil rtiTt' TV- JHTHOIIH ll sillUll- kVilH HCIlt rticiiltiti) nth, uikI 'n-sfiitly Artirii- luliniiit!, lion;;!) in I'd 1h'. or ;.'il(im for lult-rstoiMl istinct to l!^ II ;;t'ii. I i'liiiiiliur (•»' would liriciilt to lis aiidililu tJTcfl sne- tlio otlicr. ' iiiin-coy- i|llltllOll<{lll w). Ill/ (in on;), wcro lur), nwer ilciiu'utary irfjcst onil , und e (in the voltaic rosistunco liii;^ to one Whih- the was tiiitped into wiilfi iii«'lii«l(Hl in tlio circuit. A hoiiiuI pHNTcilcil from tlic diittiiiit tclr|ihoi;c. When two tiiiiiii)r-t'orkM of ililVcrcnt pitrh were coiiiicrlcd loj^rtlifr, mill Hiniiihaiu'oiiHly chiihciider wlieii dilute siil- phuri«; acid, or a Hatnratcd Hohition of Halt, was Hiiltsiitnteil for tli« water. Aiidihle ctl'ects weru also produced hy tln^ vihration of pliuiiha^o in mercury, in u Molution of hichromate of potash, in salt and water, in dilute sulphuric acid, and in pure water. I \. Sullivan * disc*»vcred that a current of (electricity is peiierated l»y the vihration of a wire <;oni|M)«ed partly of one metal and partly of another: and it is prohahle that electrical iindulatioiiH were caused hy the vihration. Tin; current was produced ho loii); as the wire emittiHl u musical note, hut Htopped immediately upon the cessation of tlio (iouiid. I.'). Altliou<;h sounds proceed from the armatures of elect ri>-iiiai;iiels under the iiitluem-e of iiiidiilatory currents of electricity, 1 have heeii nii- aide to det«'Ct any audihie ettects diu! to the electro-maj^nets theniselvus. An iiiidiilatory current was passed through the coils of au electro- magnet which was held closely against the ear. No sound was per- ceiveil until a piece of iron or steel was pn-sentcd to the pole of llio mauiiet. No sounds either were ohserved when the undulatnrv cur- I'eiit was passed through iron, stetd, retort-carhon, or plumbago. In these respects an undiilatory current is curiously diirerent from an inter- mittent on*'. (See par. 2.) ](>. The telephonic efiects descrih.ni above are produced by three distinct varieties of currents, which I term resp<'Ctively intermitlent, pulsatory, and midulatory. Jntcrnuttfnt rurrt-nts are chaiaclerlzed by the alternate presence and absence of electricity up(»n the circuit; Piihntory ciirrentg result fi-om Kiidden or instantaneous changes in the intensity of a coiitiiiuous current; and iiinhdiitury riirnnts are pro- duced by gradual <"liaiiges in the intensity of a current analo<;ous to the (changes in tin- di-iisity of air occasioned by simjde peiididous vibrations. The varying intensity of an undulatory current can be * Siillimn. " Currents of Kluctricity produccil by tliu vibration of Mt-tala. riiil. Mag., 1845, p. 201 ; Arch, de rfilcctr., X., p. 4»0. 10 PROCEEDINGS OP THE AMERICAN ACADEMY i ropreseiite J \ Keversed. J T 1 1 i Direct. ( Induced. < ,, , /o q\ '^ ( Uevcrscd (See par. H). ^ Direct (See par. 'J). ^ Iltnersed. < Direct. ( Reversed. S Dinnt invaluable as a rheimieter, for an ordinary galvanometer is of little or no use when "telephonic" currents are to l)e tested. For instance, the galvanometer needle is insensitive to the most jiowerful undulatory current when the impulses are reversed, and is only slightly deflected wlien they are direct. The nuinonietric cap- sule, on the other hand, affords a means of testing the aniplitu