Description of a Magneto-Electric Machine, ^c. 133 



be attached to one pole of the battery, and the communication 

 between the other extremity and the other battery pole be alter- 

 nately made and interrupted by means of a rasp or toothed wheel, 

 magnetism will be induced and destroyed in the iron bar and con- 

 sequently an electric current will circulate through the fine wire. 

 The use of the brass disk is to prevent by means of a closed cir- 

 cuit, any immediate induction in the fine from the coarse wire, 

 which would inevitably take place were none interposed, and 

 which would convert the instrument from a magneto-electric to 

 an electro-magnetic machine. 



Since the above was devised, an obvious improvement has sug- 

 gested itself. This is founded upon the fact that magnetism is 

 strongest at the extremities of bodies ; and consists simply in di- 

 viding the bar into three equal spaces by means of two disks of 

 brass similar in size to the one already described. The central 

 division is then to be wound with the coarse and the two outer 

 or polar divisions with the fine wire, connecting the two outer 

 helices in such a manner that they may form one long wire. 

 The battery current is then to be passed through the coarse wire, 

 and the connection made and interrupted as before by a rasp or 

 other interrupting apparatus. As thus constructed, the instru- 

 ment would produce effects similar to the common magneto-elec- 

 tric machine when used for shocks or decomposition. If it be 

 desired to produce sparks and deflagrations, it would only be ne- 

 cessary to slide oft" the coils of fine wire from the poles, and to 

 substitute in their stead others made of coarse wire of shorter 

 length and then transmit and interrupt the current through the 

 central coil as before. We should then have within a much 

 smaller compass, an instrument capable of producing all the ef- 

 fects of the common machine of Mr. Saxton, and by combining 

 a number of such bars we might form in a comparatively small 

 compass a magneto-electric battery of great energy. Some of 

 Dr. Page's beautiful interrupting apparatus might doubtless be 

 used successfully with this instrument. As I have no opportu- 

 nity to construct the instrument myself, I would suggest the trial, 

 especially of the latter form of apparatus, to any who may be in- 

 terested in the subject. Should it succeed, its advantage would 

 be its superior cheapness and power, (?) and the little space it 

 would occupy. 



About the same time that the above instrument was devised, 

 in looking over the list of substances which are capable of form- 



