INERTIA. 



37 



by the heavenly bodies will be treated of later. We will first consider 

 Inertia. 



There are several experiments relating to the subject of Inertia which 

 may be performed. I once witnessed one quite accidentally when taking a 

 walk. 



I was one day passing the Observatory at Paris, when I noticed a 

 number of people collected round a professor, who after executing several 

 juggling tricks, proceeded to perform the curious experiment I am about to 

 describe. He took a broomstick and placed it horizontally, passing the 

 ends through two paper rings. He then asked two children to hold the 



Fig. 31. Another exjeriment on the same subject. 



paper rings by means of two razors, so that the rings rested on the blade. 

 This done, the operator took a stout stick, and, with all his strength, struck 

 the broomstick in the centre ; it was broken into shivers, but the paper rings 

 were not torn in the least, or even cut by the razors ! One of my friends, 



M. M , a painter, showed me how to perform this experiment as 



represented in the illustration (fig. 30). A needle is fixed at each end of the 

 broomstick, and these needles are made to rest on two glasses, placed on 

 chairs; the needles alone must be in contact with the glasses. If the broom- 

 stick is then struck violently with another stout stick, the former will be 

 broken, but the glasses will remain intact. The experiment answers all the 

 better the more energetic the action. It is explained by the resistance of 



