ABSTRACTS OF SCIENTIFIC PAPERS 351 



success, that they may almost be said to form a new branch of elec- 

 trical science. The whole subject has been rescued from empiricism, 

 and made the matter of accurate measurement and calculation. . . . 



' The measurement of resistance has perhaps hitherto attracted 

 more attention than that of the other electrical quantities ; and re- 

 sistance coils, based on different arbitrary units, are sent by exhibitors 

 from France, Switzerland, Germany, and Italy, as well as by English 

 makers. Xo two of those sent even from the same country are 

 alike ; a state of things attended with much the same inconvenience 

 to electricians as would be felt by engineers if every man chose the 

 length of his own footrule. Except those founded on the so-called 

 absolute measure, none of the units have been chosen with any refer- 

 ence to the other electrical quantities, and still less with any regard to 

 the units of force and work/ After referring to ' the beautiful and 

 coherent system of Weber and Thomson for the expression of these 

 quantities in absolute units, chosen with reference to their relations 

 with each other and with the units of force and work which must 

 henceforth be looked on as the connecting link between all physical 

 measurements,' the author continues 'This admirable system, 

 which cannot fail of ultimate adoption, is not yet so generally known 

 as to have produced many instruments intended specially for its 

 illustration or practical application. . . .' 



' Next may be mentioned the instruments used for the automatic 

 regulation of the carbon electrodes of electric lamps. Xo less than 

 eight distinct contrivances are shown for this purpose : some more 

 suitable for optical experiments, some for signals, and some for 

 lighthouses or similar practical applications. Faults mio-ht still be 

 found with each instrument, but it is impossible to watch the quiet 

 steady flame of Mr. Holmes light, or to see M. Serrin's lamp extin- 

 guished and relighted at a distance twenty times a minute by the 

 simple interruption and re-establishment of the electric current 

 without feeling that on future occasions electric lamps will be classed 

 rather among the practical applications of electricitv than amonf 

 philosophical instruments. . . . The magneto-electric light is a novelty 

 of great importance, in which steam power is substituted for the 

 voltaic battery as the generator of the powerful current required. 

 It is probable that this invention will enable the electric light to be 

 extensively used in lighthouses and elsewhere.' 



[' Rapport sur les Appareils Electriques, Exposition de Londres, 

 1862 ;' ' Annales Telegraph.' vii. 1864, and viii. 1865.] 



The next group of papers, IX. to XVI., relate to the work done by 



