Royal Institution of Great Britain, 183 



but also to allow for a small cemetery beside. Indeed, with refe- 

 rence to the last named oak, and also some of those which the an- 

 cient Germans used as castles and forts, and in one of which a 

 hermit had his cell and chapel, Mr. B. observed, that St. Bartho- 

 lomew's, in the hamlet of Kingsland, between London and Hack- 

 ney, which, beside the ordinary furniture of a place of religious 

 worship, viz. desks for the minister and clerk, altar, staircase, 

 stove, &c., has pews and seats for 120 persons, (upwards of 100 

 have been in it at the same time.) This chapel is nearly nine feet 

 less in width, and only seventeen inches more in length than the 

 ground plot of the Cowthorpe oak, — in fact, the tree occupies up- 

 wards of thirty square feet more than does the chapel. 



In the library, amongst many other interesting objects, were 

 some beautiful architectural models in plaster of Paris, by Mr. 

 Day, of Rathbone Place. 



February I2th. 



The subject this evening was in the hands of Mr. Ritchie. It 

 was Electro-dynamics, and especially Ampere's proposed applica- 

 tion of it to the purposes of a telegraph. 



After a short view of the progress of discovery connected with 

 Electro-magnetism, Mr. Ritchie examined at some length the 

 nature and general properties of magnets. A temporary magnet, 

 he remarked, might be made by a powerful magnet, in the same 

 manner as a metallic rod might have its electricity decomposed by 

 the influence of another electrified body. Let P be a metallic 

 body electrified positively, and N P' an insulated metallic rod, 

 brought near P, but not within the striking distance. Then the 

 electricity of P will attract the negative portion of the natural elec- 

 tricity of N P' to N, and repel the positive to P'. Let us now sub- 

 stitute a bar magnet for the electrified body, and a piece of soft; iron 

 for the rod N P', then the magnetic fluid (which is in all probability 

 nothing more than common electricity) belonging to the soft iron, 

 would be decomposed by that in the magnet. The pole P would 

 either bring the opposite atoms towards itself, and repel the same 

 kind to the other extremity, or arrange them in opposite directions 

 on each side of the middle — and hence the soft iron would become 

 a real magnet When the electrified body was removed, the insu- 

 lated rod exhibited no signs of electricity ; and when the magnet 

 was removed, the soil iron returned to its unmagnetised state. The 



