490 Professor Faraday, [March 22, 



Saumarez, Rear-Admiral (the Author) — Introductory Key to the Hieroglyphic 



Phraseology of the Old Testament. 4to. 1858. 

 Society of Arts— Jourual for Feb. 1858. 8vo. 

 Taylor, Rev. W. F.R.S. ifcT.ijI./.-- Specimen of the Great Bell ofWestminster 



[" Big Ben "J now being broken up. 

 Thomson, Professor W. — Specimen of the Shore-end of the Atlantic Telegraph 



Wire. 

 Vereins zur Befijrdetung der Gewerhfleisses in Preussen—Nov. und Dec. 1857. 



4to. 

 Wijidow, F. R. Esq. {the Author) — On Submarine Electric Telegraphs. Svo. 



1857. 



Professor Faraday, on Static Induction. 



(Addition to the Report of the \2th of February.') 



The inquiries made by some who wish to understand the real 

 force of the test experiments relating to static induction, brought 

 forward on the above date (page 470,) and their consequences in 

 relation to the theory of induction, make me aware that it is 

 necessary to mention certain precautions which I concluded would 

 occur to all interested in the matter : I hope the notice I propose to 

 give here will be sufficient. When metallic coatings or carriers 

 are employed for the purpose of obtaining a knowledge of the 

 state of a layer of insulating particles, as those forming the surface 

 of a plate of sulphur, it is very necessary that they should exist in 

 a plane perpendicular to the lines of the inductive force, and in a 

 field of action where the lines of force are sensibly equal. Hence 

 the importance of the dimensions given in the description of the 

 apparatus at page 472 of the report of the evening, when the induc- 

 tive surfaces are described as 9 inches in diameter, and 9 inches 

 apart. The inductive surface there mentioned is a plane : a ball 

 cannot properly be used for this purpose ; for the lines of inductive 

 force originating at it cannot then be perpendicular to the layer of 

 gold-leaf forming the coating of the sulphur. The consequence 

 would be that this layer of gold being virtually extended along the 

 lines of inductive force, i.e. having parts nearer to and parts more 

 distant from the inductric, will be polarized according to well- 

 known electrical actions, will have opposite states at those parts, 

 will show these states by a carrier, and will give results not belong- 

 ing merely to insulating particles in a section across the lines, 

 but chiefly to united conducting particles in a section oblique to or 

 along the lines. 



The carrier itself must be perfectly insulated the whole time, or 

 else a case of induction, not including the sulphur, and entirely 

 different to that set out with is established. It must not even 

 extend by elongation into parts of the field of induction where the 



