Prof. Hare's Electro-magnetic Experiments. 361 



Again: Let the machine be in the act of tabulating any 

 series, a part may be attached by means of which, whenever 

 any particular figure (a 6 for example) occurs in the units 

 place, any other number (2.3 for instance) shall be added to 

 that and all the succeeding terms : and when, in consequence 

 of this, another figure 6 occurs in the units place, then 23 

 more will be added to that and all the succeeding terms. Or, 

 if it be preferred, the number added shall be added to the 

 term ending in 6 only, and not to all succeeding ones. 



These views may appear to some persons more curious than 

 useful. They lead however to speculations of a very singular 

 and difficult nature in determining the laws which such series 

 follow : and they are uot altogether so remote from utility as 

 may be imagined. I avoid alluding to many other curious 

 properties which this machine is capable of exhibiting, as they 

 will scarcely be intelligible till the machine itself is more known 

 in the world. Indeed I fear I have already tired your pa- 

 tience with this long letter. 



LIX. A brief Account of sonic Electro-magnetic and Galvanic 

 Experiments. By Robert Hare, M.D. Professoi- of Che- 

 mistry in the University of Pennsylvania* 



OEVEN hundred feet of copper wire, nearly as thick as a 

 ** knitting-needle, were made to encircle the columns of the 

 lecture room. One end of the wire was connected with one 

 end of a large calorimotor ; the other terminated in a cup of 

 mercury — into this, a wire proceeding from the other pole of 

 the calorimotor was introduced. Under these circumstances, 

 a magnetic needle placed near the middle of the circuit, was 

 powerfully affected ; and when the circuit was first inter- 

 rupted, and then re-established by removing the wire from the 

 cup, and introducing it again, the influence appeared to reach 

 the needle as quickly as if the circuit had not exceeded seven 

 inches in extent. The needle being allowed to become sta- 

 tionary in the meridian, while the circuit was interrupted, and 

 the end of the wire being then returned into the mercury, the 

 deviation of the needle, and the contact of the wire with the 

 metal, appeared perfectly simultaneous. 



A wire was made to circulate with great rapidity, by means 

 of two wheels, about which it passed like a band. The wheels 

 being metallic, and severally connected with the different 

 poles of a calorimotor, it was found that the motion neither 



* Communicated by the Author. 



accelerated 



