544 



NA TURE 



[Oct. 2, 1884 



The little Griscom motor and the Cleveland motor are 

 of course present, driving sewing-machines and fans. 

 Edison contributes also some small motors of excellent 

 finish. Amongst larger machines there is one by Daft and 

 one by Elihu Thomson. But by far the most important 

 of all exhibits of this class is that of Mr. F. J. Sprague, 

 which shows a very great advance on anything hitherto 

 accomplished. Mr. Sprajue appears to have succeede I 

 in producing a motor which runs at a uniform speed 

 whatever its load. It is employed in driving a small 

 loom. 



In telephones there is not much new. The Clay Tele- 

 phone Company exhibits its system, with a remarkably 

 simple and efficient receiving instrument. Beyond this 

 there is absolutely nothing new. The chief interest centres 

 on the historic exhibitions of Elisha Gray, Graham Bell, 

 A. E. Dolbear, and Van der Weyde. The remarkable 

 telephones of Daniel Drawbaugh are not yet exhibited to 

 public gaze on account of pending legal proceedings. 



In telegraphy the sole novelty is the marvellous multi- 

 plex telegraph of Delaney, based upon the principle of La 

 Cour's " phonic wheel," and capable of transmitting 

 seventy separate messages simultaneously through a single 

 wire. 



Passing on to other exhibits, it should be mentioned 

 how Messrs. J. \V. Queen and Co. display a very large col- 

 lection of imported apparatus, including the finest instru- 

 ments of Elliott Brothers, Carpentier, Breguet, Hartmann, 

 and Edelmann. Some excellent measuring-instruments 

 by the Electric Apparatus Company of Troy, N.Y., are 

 also shown. A collection of a curious and instructive 

 nature was exhibited by the U.S. Patent Office, consisting 

 of the historic models sent by inventors. Here may be 

 seen the original Edison telephone, the original Brush 

 dynamo, the original Edison lamp, and many other similar 

 objects, including many old forms of electric motor dating 

 from the years 1840-50. A special effort has also been 

 made to get together a complete modern library of books 

 bearing on the science of electricity. Some six thousand 

 volumes have in this manner been procured, and form a 

 valuable collection. 



The Franklin Institute of Philadelphia, which has 

 organised this Exhibition, must be congratulated on the 

 energy and enterprise which it has put forth. It would 

 be impossible to get together a collection of apparatus 

 more thoroughly representative of the solid progress 

 made in electro-technics on the American continent. 

 Though the Exhibition is yet far from complete, it has 

 become much more so since its opening on September 2. 

 It will remain open until October 11. 



A NEW APPLICATION OF INDIA-RUBBERS 

 I F iron takes the lead among articles of modern industry 

 *■ in the extent and number of its applications, it yet 

 falls short of india-rubber in their variety. This latter 

 article, indeed, promises soon to attain a universal diffu- 

 sion. Its industrial career, though little more than just 

 begun, already outstrips that of most substances that were 

 first in the field. 



The mere enumeration of its qualities would suffice to 

 account for the diversity of its applications. It possesses 

 so great an elasticity that by this quality alone it adapts 

 itself to a thousand different uses — brace-bands, garters, 

 sides of boots, &c. 



Observe how, if not the lightest, india-rubber is at least 

 the most powerful reservoir of mechanical energy known. 

 It lends itself most readily to the restitution, under the 

 form of mechanical labour, of the energy imparted to it 

 by tension, and this restitution may be effected with re- 

 markable quickness. It is owing to the relative lightness 

 of india-rubber considered as an accumulator of energy, 

 and, above all, to its power, that the exactness of the 



1 From La Nature. 



principle of " heavier than air " may be demonstrated on 

 a small scale. 



From an electrical point of view, india-rubber acts as a 

 better insulator than gutta-percha, and is, indeed, one of the 

 best insulating bodies known. At the same time that its 

 specific inductive capacity is weaker than that of gutta- 

 percha, it does not become plastic at a moderate 

 temperature. These properties render it an excellent 

 insulator in electrical applications : submarine and sub- 

 terranean telegraphy, electric light, transmission of force, 

 &c. While it insulates better than gutta-percha, the con- 

 ductor, where india-rubber is used, does not run the r;sk 

 of being put out of centre, as is the case sometimes with 

 gutta-percha. 



India-rubber is known to oxidise under exposure to air 

 and light ; above all, under alternations of dryness and 

 damp. By subjecting it, however, to a special operation, 

 called vulcanisation, a product is obtained which main- 



whkh household utensils fumi 

 may be placed without falling. 



hed with india-rubber 



tains its flexibility at low temperatures, resists heat much 

 better, does not oxidise in air, and absorbs less water. It 

 is especially under the form of vulcanised india-rubber 

 that its applications are numerous. 



There is, finally, a third form of india-rubber, no less 

 useful, that of ebonite, or hardened india-rubber, a form 

 which combines with its lightness and great electrical re- 

 sistance, the further advantage of resisting acids, and 

 which is therefore exclusively employed when vessels for 

 the electric pile or other reservoirs of a light and not 

 readily brittle character are wanted. Like a new Proteus, 

 india-rubber is thus seen to adjust itself to the ever more 

 numerous and pressing demands of modern industry. 



To turn now to the new, curious, and original applica- 

 tion an idea of which it is the object of this notice to 

 convey. The aim of the inventor, whose name unfortu- 

 nately has not reached us, has been to take advantage of 

 the great mutual adherence of a soft and a hard body. It 

 is by the utilisation of this relation that the inventor has 

 originated quite a series of household objects in earthen- 



