EDITOR'S TABLE. 



3 6 7 



thi3 work with such conspicuous suc- 

 cess as the distinguished man to whom 

 it was so fortunately intrusted. 



It may be added that, in a business 

 point of view, the establishment has 

 been managed with great skill and effi- 

 ciency. The amount of money received 

 from Smithson, in 1838, was $515,000, 

 to which was added in 1865 a residuary 

 legacy of Smithson amounting to $26,- 

 000 ; and, notwithstanding that a large 

 portion of the fund has been absorbed 

 in building, all the plans of Prof. Henry 

 have been carried out, and the fund 

 now available exceeds $700,000. 



MAGNIFYING SOUND. 



How scientific discoveries run in 

 groups, one thing suggesting another 

 so quickly as to make an epoch, is just 

 now illustrated anew in the field of 

 acoustics, and with the usual result of 

 rival claims and disputed priority. 

 Following the telephone and growing 

 out of it comes another remarkable 

 revelation, that minute sounds may be 

 magnified to the ear as minute objects 

 are magnified by lenses to the eye. 



The telephone, in transmitting sound, 

 greatly reduces or minifies it, and it 

 therefore became a problem for ex- 

 perimenters to find out how sounds can 

 be transmitted with the least loss of 

 volume and intensity. Mr. Thomas A. 

 Edison early attacked this problem 

 with his usual assiduity and fertile in- 

 ventiveness. Operating upon many 

 hundred substances of diverse qualities 

 and in varying conditions to test their 

 sonorous capacities under electrical in- 

 fluence, he found that carbon possess- 

 es this singular property in a very re- 

 markable degree. He found, moreover, 

 that the effect varies with the pressure 

 upon the carbon, and, what is more as- 

 tonishing still, that it varies so greatly 

 with the small differences of pressure 

 produced by the passage of sound- 

 waves as to alter the flow of the elec- 



trical current. More than a year ago 

 he embodied this principle in the " car- 

 bon telephone," by which the capaci- 

 ty of the instrument was greatly aug- 

 mented. 



But now Prof. D. E. Hughes, al- 

 ready well known as the inventor of 

 the type-printing apparatus that bears 

 his name, comes forward with an ar- 

 rangement involving the same property 

 of the same substance, but developing 

 almost incredible effects. He claims 

 to have reached these results in his 

 own way, as follows : Following a hint 

 of Sir William Thomson in regard to the 

 molecular change and conductivity of 

 wires under mechanical strain, he insert- 

 ed a stretched and strained wire in his 

 telephonic circuit. But no effect was 

 produced until it broke, when a sound 

 was given out so curious and marked 

 that Prof. Hughes followed it up, by 

 pressing the broken ends together, when 

 the new effect was faintly reproduced. 

 Following this suggestion, he introduced 

 other pieces so as to have broken or 

 imperfect connections, when the faint 

 sounds were improved. Iron nails or 

 a steel watch-chain also answered the 

 purpose. 



Prof. Hughes says he found the same 

 property in porous charcoal, and that 

 it was heightened by infiltrating the 

 carbon with metallic mercury. The 

 part introduced into the circuit Prof. 

 Hughes calls the " transmitter," and 

 the arrangement which he recently ex- 

 hibited to the Pioyal Society consists of 

 a glass tube two inches long, and one- 

 fourth inch in diameter, filled with a 

 series of plugs of mercurialized carbon, 

 the end-plugs being attached to the 

 wires of the circuit. He uses a small 

 three-celled galvanic battery to furnish 

 the current, and, with the transmitter 

 introduced, sounds otherwise perfectly 

 inaudible by the ear are not only heard, 

 but are conveyed to great distances by 

 the telephone. The surprising thing is 

 that when these pieces of carbon bare- 

 ly touch each other the electric current 



