1838.] 



Electro-Magnetic Motor.a. 



185 



energy with the electro-magnets, than with those that were permanent, 

 for with the smallest battery, whose diameter was thrte inches and a 

 half— its height five inches and a half, and the number of concentric 

 cylinders three of copper and three of zinc, the instrument manifested 

 c.-i great power as it had done with the largest batteries, and even with 

 :i large calorimotor, when it was used with a permanent instead of a 

 galvanic magnet. With the small battery and with none but electro 

 or galvanic magnets, it revolved with so much energy as to produce 

 a brisk breeze, and powerfully to shake a large table on which the 

 apparatus stood. 



Although the magnetization of both the stationary and revolving 

 magnets was imparted by one- and the same battery, the magnetic 

 power was not immediately destroyed by breaking the connexion be- 

 uvecn the battery and the stationary magnet; for, when this was 

 done, the machine still performed its revolutions W'ith great, although 

 diminished energy ; in practice this might be important, as it would 

 give time to make changes in the apparatus, without stopping the 

 movement of the machine. 



Conclunons.— l. It appears, then, from the facts stated above, that 

 electro-magnetism is quite adequate to the generation of rotary motion. 



2. That it is not necessary to employ permanent magnets in any 

 part of the construction, and that electro-magnets are far preferable, 

 not only for the moving but for the stationary parts of the machine. 



3. That the power generated by electro-magnetism may be indefi- 

 nitely prolonged, since, for exhausted acids and corroded metals, fresh 

 acidf? and batteries, kept always in readiness, may be substituted, even 

 without stopping the movement. 



4. That the power may be increased beyond any limit hitherto at- 

 tained, and probably beyond any which can be with certainty assigned; 

 since, by increasing all the members of the apparatus,— due reference 

 being had to the relative proportionate weight, size, and form of the 

 fixed and m oveable parts, to the length of the insulated wires, and 

 the manner of winding them, and to the proper size and construction 

 of the battery, as well as to the nature and strength of the acid or 

 other exciting agent, and the manner of connecting the battery with 

 the machine,— it would appear certain, that the power must be in- 

 creased in some ratio which experience must ascertain. 



5. As electro-magnetism has been experimentally proved to be 

 sufficient to raise and sustain several thousands of pounds, no reason 



