462 Dr. Ritchie in reply to The Rev. J. W. MacGauley. 



ducing decomposition as a battery of 1000 or 2000 pairs of 

 plates. 

 Maynooth College, Feb. 12, 1836. 



Dr. Ritchie iii reply to the Rev. J. W. MacGauley. 

 (Seep. 130.) 



Mr. MacGauley describes the results stated in my paper 

 contained in the Phil. Mag. for June 1836, as " perfectly at 

 variance with the truth." The following is his version of my 

 statement : " It is a well-known fact, that we receive a more 

 powerful shock when electricity is being induced on a body, 

 than when the induced electricity is returning to its natural 

 state." The quotation is quite correct, — except the substitution 

 of the indefinite article a, for the definite article the, before 

 the word body. This slight substitution makes " my talk very 

 egregious nonsense." My original statement is, that the shock 

 is most powerful when the electricity is being induced on the 

 (human) body, and I may further add, that this is always the 

 case, whether the shock result from a single wire which has 

 been connected with the voltaic battery, or from the coil of 

 an electro-magnet. My statement therefore has no reference 

 whatever to the electric state of the wire, or in other words, to 

 the question, whether the electricity of the wire is hemg forced 

 from its state of equilibrium or returning to its natural state. 



Mr. MacGauley has also mistaken the experiments of Dr. 

 Faraday on the length of the coil influencing the electric spark. 

 His experiments were made with a single wire, either in one 

 continuous length or in the form of a coil, mth a galvanic 

 battery alone. The shock from a long wire has long since 

 been obtained by Professor Henry of America. Mr. Mac- 

 Gauley speaks of an electro-galvanic h^Yvs. as a species of elec- 

 tric machine of almost unlimited energy. There is nothing, 

 however, gained by forming it into a helix, the single con- 

 tinuous wire of the same length being equally efficacious. The 

 following quotation clearly shows that the author really knows 

 nothing of Faraday's admirable investigations : " The asser- 

 tion I do make is this, and I repeat it, that if the iron of an 

 electro-magnet retain, from the nature of its material, the pre- 

 sence of a keeper, or any other cause, the magnetism induced 

 upon it, the shock and spark will be proportionally diminished, 

 because the magnetism of the bar, by its inductive action on 

 the helix, would prevent the perfect restoration to equilibrium 

 of the electricity disturbed in the helix, by giving to the bar 

 in a greater or less degree the nature of a permanent magnet, 

 from which, by means of a helix coiled around it, neither 



