1865.] 151 [Chase. 



Mr. Lesley described some relics lately exhumed from In- 

 dian ffraves near Wilkesbarre. Dr. Coates referred to the 

 wearing away, without decay, of the teeth in skulls found in 

 tumuli and graves on the West Branch Susquehanna and 

 elsewhere. 



Mr. Chase presented a detailed account of his experiments 

 upon the Mechanical Polarization of Magnetic Needles under 

 the influence of Fluid Currents, or Faraday's " Lines of 

 Force." 



I have already published three simple experiments in mechanical 

 polarization (Proc. Amer. Philos. See., ix, 359), and I have endea- 

 vored, in various ways, to show that terrestrial magnetism is probably 

 owing to an analogous polarization of aerial and sethereal currents. 

 Finding that my hypothesis was sustained by some remarkable nu- 

 merical coincidences, as well as by various points of correspondence 

 between the assumed influence of gravitation-currents and the ob- 

 served daily variations of declination and inclination, I sought for 

 some practical demonstration of the truth of my inferences. I there- 

 fore endeavored to imitate the movements of the atmosphere by me- 

 chanical contrivances, and the results, which are in most respects 

 such as I anticipated, and which are all susceptible of an easy expla- 

 nation, are embodied in the following additional experiments. 



4. By the use of fans, bellows, and blowers of various kinds, 

 either alone or in conjunction with directing discs, currents may be 

 produced that will deflect the needle in any desired direction, in ac- 

 cordance with simple and evident mechanical laws. 



5. I have tried iron, copper, wood, zinc, and pasteboard, and find, 

 as I anticipated, that the material employed for producing or direct- 

 ing the artificial currents has no eff'ect upon their mere mechanical 

 action ; but I have found the results most satisfactory when, in order 

 to avoid the complication of induced magnetism or electricity, I em- 

 ployed non-conductors, such as wood and pasteboard. Upon subse- 

 quently repeating the experiments with diff"erent metals, the efiiects 

 of the induced currents have been plainly shown. 



6. Increasing the number of directing discs (provided they are 

 all parallel) often modifies the intensity of current-influence, but does 

 not appear otherwise to affect the result. 



The most striking developments that I have yet hit upon were ob- 



VOL. X. — w 



