446 Electro-magnetic Experiments. 



interesting and so rate ; but it has appeared to me proper, never- 

 theless, to collect here all the observations on the solar disc made 

 on the 26tii of June IS 19, of which I have been able to receive 

 an account." 



LXXXIV. Electro-magnelic Experiments. By Mr. J. Tatvm. 



J. Dorset-street, May 17, 1821. 



Sir, — If you are of opinion that the following arrangement 

 of Electro-magnetic Apparatus, and experiments performed with 

 it, are worthy of a place in your publication, they are at your ser- 

 vice. I am, sir, yours, &c. 



J. Tatum. 

 To the Editor of the Phil. Mag. 



Let A, B, C and D (fig. A, Plate IV) represent a copper ves- 

 sel about four inches by three, and about half an inch wide, in 

 which is inserted a plate of zinc z z, similar to that of Professor 

 Oersted, as described in your Magazine for January, page 46, ex- 

 cepting only that that was suspended by means of a loop of thread, 

 and thi*; is supported by a fine point, at the bottom, and one at 

 the top of the copper vessel, so as to allow it to rotate freely 

 when put in action by a very small power. Let E, F, G, H and I 

 represent a copper wire soldered to the plate of zinc at E, and 

 continued toF, where it is bent at a right angle, and continued to 

 G, H, and I, where it is soldered to one side of the copper vessel. 



Let the copper vessel be filled with diluted nitro-sulphuric 

 acid, and the following phaenomena will be observed. 



1. On bringing the north pole of a strong magnetic bar under 

 the copper wire near G, the apparatus will be strongly repelled, 

 and rotate quickly on its axis. 



2. If the south pole of the same bar be presented, the appa- 

 ratus will as quickly rotate by attraction. 



3. On bringing the north pole above the wire near F, the 

 apparatus will rotate by attraction. 



4. But on approaching the same part of the wire, with the 

 south pole of the magnet, the apparatus will rotate by repulsion. 



5. If some fine iron filings be sprinkled or dropt on the wire, 

 or if a piece of paper containing such be brought under the same, 

 so as it niav touch them, they will adhere to it in little clots. 

 This experimei.t succeeds if the wire be brass or platina. 



6. If the north pole of a magnetic needle be brought under 

 the wire, it is violently repelled. 



7. If the south pole be presented to the same part, it will be 

 attracted. 



8. On 



