NATURAL PHILOSOPHY. 165 



The -whole of this difference, according to Professor Farraday, depends 

 upon the lateral induction of the wire carrying the current. " The pro- 

 duction of a polarized state of the particles of neighboring matters by an. 

 excited body constitutes induction, and this arises from its action upon the 

 particles in immediate contact with it, which again act upon those contigu- 

 ous to them ; and thus the forces are transferred to a distance. If the 

 induction remain undiminished, then perfect insulation is the conse- 

 quence ; and the higher the polarized condition which the particles can. 

 acquire or maintain, the higher is the intensity which may be given to the 

 acting forces. In a word, insulators may be said to be bodies whose parti- 

 cles can retain the polarized state ; whilst conductors are those whose 

 particles cannot be permanently polarized." And in regard to long cir- 

 cuits such as those described, their conducting power cannot be under- 

 stood ; whilst no reference is made to their lateral static induction or to the 

 conditions of intensity and quantity which then come into play. 



The conducting power of the air and water wires are alike for a constant 

 current. This, according to Farraday, is in perfect accordance with the 

 principles and with the definite character of the electric force, whether in 

 the static, or current, or transition state. When a voltaic current of a 

 certain intensity is sent into a long water wire, connected at the farther 

 extremity with the earth, part of the force is in the first instance occupied 

 in raising a lateral induction round the wire, ultimately equal in intensity 

 at the near end to the intensity of the battery stream, and decreasing gradu- 

 ally to the earth end. 



In the report of Farraday, which is given in the London Philosophical 

 Mayazine for March, he there, in conclusion, refers to the terms intensity 

 and quantity. These terms, he remarks, or equivalents of them, cannot be 

 dispensed with by those who study both the static and dynamic relations 

 of electricity. Every current, where there is resistance, has the static 

 element and induction involved in it, whilst every case of insulation has 

 more or less of the dynamic element and conduction ; and we have seen that 

 the same voltaic source, the same current in the same length of the same 

 wire, give a different result, as the intensity is made to vary with varia- 

 tions of induction around the wire. The idea of intensity, or the power of 

 overcoming resistance, is as necessary to that of electricity, either static or 

 current, as the idea of pressure is to steam in a boiler, or to air passing 

 through apertures or tubes ; and we must have language competent to 

 express these conditions and these ideas. 



In conclusion, I trust that a cable may be laid across the briny deep, 

 and I am happy to find the matter taken hold of by intelligent and scien- 

 tific telegraphic engineers ; and its completion will be one of the wonders 

 of the age. 



In relation to the ultimate completion of the transatlantic submarine 

 telegraph, Mr. Shaffner, a gentleman who has had considerable experience 

 in submarine telegraphic lines during the last five years, employs the 



