3*8 



Mr. Joule on the Calorific Effects 



In the preceding series I used the steel magnets previously 

 described as the inductive force : and I had two of the large 

 Daniell's cells in series, arranged so as to pass a current of 

 electricity through the revolving electro-magnet and galvano- 

 meter. The wheel was turned in the direction which it would 

 have taken had the friction been sufficiently reduced to allow 

 of the motion of the apparatus without assistance. The pre- 

 caution of interpolating the experiments was again adopted. 



I give another series, in which everything else remaining 

 the same, the direction of revolution was reverse, so as to 

 increase the intensity of the voltaic electricity by superadding 

 that of the magneto-electricity. 



No. 8. 



Circuits 



complete, 



Circuits 



broken. 



Circuits 



complete, 



Circuits 



broken. 



Circuits 



complete, 



Circuits 



broken. 



Mean 

 Circuits 

 complete, 



Mean 

 Circuits 

 broken. 



Corrected 

 Result. 



Revolu- 

 tions of 

 Electro- 

 Magnet 



per 

 minute. 



J600 

 1-600 

 J600 

 J600 

 1 600 

 1 600 



600 



600 



Deflec- 

 tions of 

 Galvano- 

 meter of 

 1 turn. 



o / 



30 15 





 29 40 





 29 50 







29 55 



Mean 

 Tempe- 

 rature 



of 

 Room. 



60-55 

 62-28 

 60-90 

 59-50 

 6185 

 60-90 



Mean 

 Differ- 

 ence. 



019+ 



048 4- 



003- 



00 



0-18- 



0-49- 



Temperature of 

 Water. 



Before. After, 



59-30 

 62-92 

 59-50 

 59-50 

 60-33 

 60-50 



62-18 

 62-60 

 62-25 

 59-50 

 63-02 

 60-33 



Loss or 

 Gain. 



2-88 gain, 

 0-32 loss. 

 2*75 gain, 

 



2-69 gain. 

 0-17 loss. 



2-77 gain, 



0-16 loss. 



600 29° 55' = 1-346 of current. 



2-93 gain 



Dismissing the steel magnets, which did not appear to have 

 lost any of the magnetic virtue, which they possessed when 

 newly made, I now substituted for them the large stationary 

 electro-magnet, excited by eight of the DanielPs cells arranged 

 in a series of four double pairs. The revolving electro-mag- 

 net completed, as before, a circuit containing the galvanometer 

 and 2 of DanielPs cells in series. The motive power of the 

 apparatus was now so great that it would revolve rapidly in 

 spite of very considerable friction. In order to give the re- 



