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Show THE EADI0PH0NE, TalkltiB Through Bpao by Moana of Heat Ray, , 1$ A Poinltrrul InTentlon f JProT, Ball'a liihlbltlon at tlio Vrrld' rr Itotr th loatromot la Work. 4. j IIlU'h radlophono, by wlilch conTi sntlon it transmitted through space on I n, rny oi light, no wires or electricity I Uolnjr used In nny portion of tho npptr-I npptr-I ntus, la ono of tho scientific wonders at tho world's fnlr. Tho photophono, by which a telcphono is caused to re-! re-! Gpotul to tho variations in Intensity of it light ray falling upon a selenium I cell placed in n local electric circuit la I familiar. Trof. Aloxandcr Graham Hell Miccccdcil In transmitting artleif ' lato speech in this way by making a beam of light, which a mirror reflects, I vibrate, tho vibrations being of tho j r.amo hind as thoso produced by speak Ing through n membrane. He used a I thin mica orglass plate as a diaphragm, 1 which by being allrered served at tlte wimo tlmo as a mirror. The reflected 1 rayot light as It full upon tho selenium I cell at the distant point varied in In-j In-j tensity in unison with the sound waves which caused tho vibration of the dla- phragm mirror. The varying Intensity f th light produces In tho selenlnm cell n corresponding variation in tho leslstnncc of tho local circuit, and the varying current which results there from It translated into sound waves by tlio telephone, which correspond exactly exact-ly with the sound waves which vibrated the diaphragm. Trof. Hell pursued his investigations looking to obtaining sounds without tho addition of a local circuit, and his latent production, that which is now nbout ready for exhibition in the Ilell telephone pavilion In Electricity building, build-ing, mny bo briefly described as follows- In tho northwest gallery, overhanging over-hanging tho main floor a few feet, thcro has been erected a small platform, plat-form, upon which tho sending apparatus appa-ratus is placed. This consists of a focusing arc lamp of ordinary pattern, whoso rays, rendered parallel by a lent, aro reflected from a thin diaphragm mirror to tho receiving instrument about eighty or ninety feet away, at tho north front of the Hell telephone pavilion. Tho reflecting mirror in a (Unit of very thin glusa, silvered on Its n-UTse nido and held In a heavy brasa fraino by menus of washers of ordinary blotting paper. Opening into the chamber in tho rear of this mirror is ttn ordinary spenklug tube, into which the Hounds nro uttered, causing the miiror to vibrato as would the dia-phrngm dia-phrngm of a telephone transmitter. Thebo rays, reflected in parallel linvu, arc recolvcd at tho farther end by a parabolic reflector, in the fdeutot which U placed a glass bulb, contain-Intfa contain-Intfa htnnll poition of ordinary burnt cork Tlio bulb is blown into tho end of n glass tubo about a quarter of an inch in diameter and four Inches long, tlio other end of which is opcu, and to -KTcli l uilaclicd an ordinary phono- graph hearing tube, which extends into n i.mall cabinet, where tho listener, liste-ner, removed from external noises, re-C( re-C( Ivci tho message Tho only adjustments adjust-ments requited aro that the rays ba directed from the mirror In the gallery In a.) nxinl direction Into tho parabolic) n OVctoi, nnd that the bulb containing tlio burnt corlc bo brought to the focus of the parabolic mirror. This latter la accomplished by pushing tho glass, tubo in or out until satisfactory re-suUnnro re-suUnnro obtained. Certainly nothing could bo elmplcr than this; but, although al-though tho luatrumont is of great scientific sci-entific Interest, it has no apparont practical value. Tho transmitted words, U3 hcaid through tho hearing tuliun, hide shnrpnessof definition anil have n Mimcwhat muffled sound, which I- pi i' -lily duo to tho tube effects. Tho conversation can, however, be falrl. uutlerMood If one knows beforehand before-hand Vi hat W to bo expected, but II would bo dlfllcult to follow an ex-pi ex-pi cwiou for which ono wss.oot pre-puicd pre-puicd Trof, Hell has given the following fol-lowing explanation of the philosophy of t!m phenomenon: When the Intermittent Inter-mittent beam strikes upon the receiver, re-ceiver, tho particles are alternately heated nnd cooled; when they are heated they expand, and consequently the intervals which aro filled with air uru diminished; when the light is Intercepted Inter-cepted the pirtlclcs are cooled and the np.iccti between them enlarged. Air is squeezed out from the interstloesbe tueuiitho particles In tho first earn and drawn in in tho latter; tho enlarging enlarg-ing of tho Intervals causes refraction of lliu air In the cork particles; aud tlin miti'r ntr nlshos In: thft eontmeUnn of tho interstitial spaces eausos condensation con-densation and cscnpo of the air they contain.. Thcso two effects aro still further increased by tha heating and cooling of tho air in tho intervals alternately al-ternately increased and diminished, liy tlieso menus alternate waves of compression and rarefaction are produced pro-duced In the surrounding all, and il is to this that the sound which is emitted owes Its existence. FFiESH FOREIGN FACTS. The population of Urcece is Increa Ing fnbter than that of any other coun-tiy coun-tiy in liuropo at present. A Hwnuten anarchist has started ar nur.rchlstlo Sunday-School nt Nordkop luf, n city of about 30,000 Inhabitant) in bwedon. Tun coachmen of IJcrlln wear a ilia ttnctlto hat when conveying phystclaui mid ttro granted tho right of way by i city oidlnanec. A drpoc In Glasgow has decided tha tho nmount of copper used In tlnucc prrccn p-'au wns not dangerous, ami thai the process need not bo stopped. Tnr population of St. Tutersburg Is steadily dimlnlihlng It Isles by o,lghty-live o,lghty-live thousand than It was at thu census t.iUi n Mvcn ycaro ago. No other Ltoropenn capital Is thun dearpyitluz. In I runco u new "magto mirror" has I itcTy been Introduced. It ccnsUts us-scntiully us-scntiully of a glass platu. loiUmI with a film of platinum so thin as to bo transparent trans-parent to light coming through from I I liind, while liofng a tfuo mirror or ro-ik'Uur ro-ik'Uur to light Impinging It from the tront. 1 , , " , , - i |