202 NOVUM OROANUM 



a spring, and let them be set well together, so that one be 

 neither quicker nor slower than the other; then let the clock 

 moved by weights be placed on the top of a very high 

 church, and the other be kept below, and let it be well 

 observed, if the former move slower than it did, from the 

 diminished power of the weights. Let the same experiment 

 be made at the bottom of mines worked to a considerable 

 depth, in order to see whether the clock move more quickly 

 from the increased power of the weights. But if this power 

 be found to diminish at a height, and to increase in subter 

 raneous places, the attraction of the corporeal mass of the 

 earth may be taken as the cause of weight. 



Again, let the required nature be the polarity of the 

 steel needle when touched with the magnet. We have these 

 two ways with regard to this nature Either the touch of 

 the magnet must communicate polarity to the steel toward 

 the north and south, or else it may only excite and prepare 

 it, while the actual motion is occasioned by the presence 

 of the earth, which Gilbert considers to be the case, and 

 endeavors to prove with so much labor. The particulars 

 he has inquired into with such ingenious zeal amount to 

 this 1. An iron bolt placed for a long time toward the 

 north and south acquires polarity from this habit, without 

 the touch of the magnet, as if the earth itself operating but 

 weakly from its distance (for the surface or outer crust of 

 the earth does not, in his opinion, possess the magnetic 

 power), yet, by long continued motion, could supply the 

 place of the magnet, excite the iron, and convert and change 

 it when excited. 2. Iron, at a red or white heat, when 



posing consequences of the two theories were noted by M. Fresnel, and the 

 result is stated by him to be decisive in favor of that theory which makes light 

 to consist in the vibrations of an elastic medium. Ed. 



