VOL. XXIV.] PHILOSOPHICAL TRANSACTIONS. 259 



tenth of an inch at each end, every part so coiled will both lose its verticity, 

 and will incline indifferently to either pole of the magnet ; but tlie two ends, 

 (although not able to turn the whole wire N. and S.) will fly from, or tend to 

 the respective pole of the magnet : or if every part of the wire be coiled, ex- 

 cept a small bit at one end only, all that coiled part, when extended, will be 

 utterly deprived of its magnetism as before ; and only that uncoiled bit retain 

 its aversion, or inclination to the magnetic poles. 



From the consideration of all which particulars, it is very manifest, that the 

 violence exerted on the wire by bending, utterly extirpates the magnetic virtue, 

 or at least makes such a confusion in it, that it is in a manner wholly destroyed: 

 which seems a case very odd, aud never I think noticed before. 



Further Observations and Remarks on the same Subject. By Mr. Derham. 



N°303, p. 2138. 



By consulting more accurately what others have written on magnetics, I find 

 that Grimaldi, de Lumine and Colore, and M. de la Hire had both hit upon the 

 same discovery before me. However, they have not prosecuted their discovery 

 so far as I did, and my account contains divers things not taken notice of by 

 them. 



However some trials that I made did not succeed. I touched and coiled 

 several iron wires, but the effect that ensued was not such as before-mentioned. 

 The verticity was indeed much weakened, but not totally destroyed, and the 

 ends of the wires would be attracted or repelled by the poles of the magnet ; 

 whereas I said they used only to be attracted. The next morning I tried again : 

 and then the magnetism of the wires was totally destroyed, as I related. This 

 experiment I repeated several times, and on various wires this winter, and com- 

 monly find, that, all the day, coiling will destroy the magnetism ; but that it 

 will not absolutely do it in the evenings. But whether it will have the same 

 effect in all seasons, or whether it succeeds thus only in different times of the 

 day, I must leave to further trials. I well know that the sphere of the activity 

 of magnets, is more or less, at different times. That magnet in the Society's 

 repository, found in Devonshire by Dr. Cotton, is known in some weathers, or 

 at some times, to keep a key, or other piece of iron, suspended to another 

 iron at 8, 9, or 10 feet distance. 



Wishing to try the event of twisting iron wire from end to end, after it had 

 been well touched ; the success was, the verticity was always weakened, and 

 sometimes inverted. And when it was so, the loadstone accordingly repelled 

 or attracted, just as if the twisting the wire had given a new touch the contrary 



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