I 



Nov. 29, 1888] 



NA TURE 



169 



therefore, on hearing the reproduction through the magnify- 

 ing funnel, are disappointed to find the effect below their 

 expectations. As soon, however, as they listen through 

 the tubes, they are proportionately surprised at the loud- 

 ness and the clearness of the sound and articulation. 

 While for most practical purposes audition through the 

 tubes is quite sufficient, Mr. Edison is, we understand, 

 constructing a means by which the sounds can be greatly 

 magnified. Even as it'is, with the present funnel the re- 

 production can be heard very well throughout a large 

 room. For example, at a lecture on November 10, before 

 Harrow School, a perfect melan^^e of speaking, singing, 

 and whistling, made by Colonel Gouraud on the spot, was 

 plainly heard all over the lecture theatre, in which about 

 600 persons were present. 



Other improvements comprise an electric motor and 

 speed governor, by which the phonogram and the feeding 

 screws can be rotated at a constant speed. As this electric 



motor is itself the subject of a separate patent, we are 

 only at liberty to say that it is an electro-dynamic multi- 

 polar motor, in which a ring armature acts as a fly-wheel, 

 and that it is adjustable to different speeds — a necessary 

 point in order to preserve the same pitch where the 

 rapidity of utterance is subject to variation. The circuit- 

 ing of the motor and governor is ingeniously arranged so 

 that the field of the armature can be opened without 

 interfering with the field-magnet circuit, thus securing 

 greater sensitiveness and an absence of sparking. 



The phonograms themselves are divided into two sorts, 

 office-grams and mailing-grams. The former are cylin- 

 ders, capable at the present time of yielding from thirty 

 to fifty surfaces for record, which number, as Mr. Edisor> 

 says in a letter only received a few days ago, can now, 

 by improved methods, be increased to two hundred. 

 Obviously, however, such a cylinder would be an awk- 

 ward affair to send by post. Mr. Edison has therefore 



Instrument turned over so as to present a top view with recording d.aphragm in position. A, recording diaphragm ; b, 

 reproducing diaphragm ; c, rocking holding arm ; d, bar f . r arresting record ; E, turning bar ; f, wax cyhndrical 

 phcn igram ; c, electnc speed governor. 



met this want by constructing the mailing-gram, and 

 though this may seem a small matter from a scientific 

 point of view, yet we venture to prophesy that amon? all 

 his many achievements there will be none to which he 

 will look back with greater pride, or which are destined 

 to work a greater revolution in the history of the world 

 than this apparently simple little mailing-gram. To say 

 that it is capable of being posted, and reproduced at the 

 other end without injury to the record, may perhaps give 

 some idea of its practical value. 



Regarding the way in which all this is accomplished, it 

 is needless to say anything, except that the device bears 

 the true stamp of genius, viz. simplicity. This portability 

 of the phonograms is, in fact, one of the salient features by 

 which the phonograph of 1888 stands out in marked con- 

 trast to the imperfect machine of 1878, and this improve- 

 ment, in combination with the greater perfection and 

 permanence of the record, at once raises it from the level 



of a pretty scientific toy or curiosity to (me of immediate 

 utility. 

 I The practical working of the instrument, which has 

 j been greatly improved even upon what it was at the 

 meeting of the British Association at Bath this year, may 

 be gathered from the fact that Colonel Gouraud dictates 

 I all his correspondence through it, speaks to it in differ- 

 ent languages, applies every conceivable test to try its 

 j powers, and with results which not only astonish him and 



everybody else, but even the inventor himself. 

 ' The purposes to which such an instrument can 

 I be applied — scientific, commercial, domestic, artistic, 

 ! military — seem countless. The dreams which were 

 I indulged in when the phonograph of 1878 appeared, 

 can now be realized ; and we owe to Mr. Edison 

 another substantial addition to the long list of direct 

 ] results of scientific labour achieved during the present 

 i century. 



FURTHER NOTES ON THE LATE ERUPTION 

 A T VULCANO ISLAND. 



IV/f Y friend Signor Gaetano Platania, who accompanied 

 ^*- me on my trip through the Lipari Islands in June 

 1887, and stayed some days with me at Vulcano, has 

 undertaken the task of describing that interesting event 

 and the subsequent phenomena. He has very kindly 

 forwarded me specimens of the ejectamenta, and to him 

 I must express my thanks. He being already well 

 acquainted with the products of that volcano, his ob- 

 servations will be of considerable value when published. 

 The first specimen submitted to me is that of the so- 

 called bombs, common in other eruptions that have taken 

 place from the present active crater of Vulcano. It is 

 undoubtedly the essential ejectamenta, although included 



in the paste is much fragmentary accessory material. 

 These so-called bombs are irregular polygonal masses of 

 an obsidian-like material on the outside ; the surfaces are 

 traversed by a number of clefts or fissures V-shaped in 

 section, which at their bottom and the deeper parts of 

 their sides are seen to be composed of a spongy glass or 

 even pumice. Their mode of formation is no doubt as 

 follows : — The glassy magma from former loss of heat 

 has become so viscous that the escape of vapours from 

 the underlying magma is arrested until the tension rises, 

 and the superincumbent pasty, almost solid, mass is 

 broken up and ejected. This ejection has been preceded 

 by some expansion and cracking, together with some 

 cooling along the cracks, so that the blocks have partly 

 consolidated as pumiceous obsidian, but when relieved 

 from these conditions by ejection, -the hotter material 



