EXCERPT FROM FARADAY'S DIARY 



Facsimile and Transcript of the page recording 



THE discovery OF ELECTRO-MAGNETIC INDUCTION * 



Aug. 29th, 1831. 



1. Experiments on the production of Electricity from 

 Magnetism, etc. etc. 



2. Have had an iron ring made (soft iron), iron round 

 and |th inches thick and ring 6 inches in external 

 diameter. Wound many coils of copper wire round, one 

 half the coils being separated by twine and calico- 

 there were 3 lengths of wire each about 24 feet long and 

 they could be connected as one length or used as separate 

 lengths. By trial with a trough each was insulated from 

 the other. Will call this side of the ring A. On the 

 other side but separated by an interval was wound wire 

 in two pieces together amounting to about 60 feet in 

 length, the direction being as with the former coils; this 

 side call B. 



3. Charged a battery of 10 pr. plates 4 inches square. 

 Made the coil on B side one coil and connected its 

 extremities by a copper wire passing to a distance and 

 just over a magnetic needle (3 feet from iron ring). 

 Then connected the ends of one of the pieces on A side 

 with battery; immediately a sensible effect on needle. 

 It oscillated and settled at last in original position. On 

 breaking connection of A side with Battery, again a 

 disturbance of the needle. 



4. Made all the wires on A side one coil and sent current 

 from battery through the whole. Effect on needle much 

 stronger than before. 



5. The effect on the needle then but a very small part 

 of that which the wire communicating directly with the 

 battery could produce. 



* Courtesy of The Royal Institution of London, England. 



