H 0f ti)t ^ecfiantcal Wgine 



a confiderable degree of Heat will 

 be quickly excited in thofe parts of 

 the iron where the File paffes to 

 and fro the many prominent parts 

 of the Inftrument giving a multi- 

 tude of ftrokes or pufhes to the parts 

 6f the iron that happen to ftand in 

 their way , and thereby making 

 them put the neighbouring parts in- 

 to a brisk and confus'd motion , and 

 fo into a ftate of Heat. Nor can it 

 be well obje&ed, that upon this ac- 

 count the File it felf ought to grow 

 as hot as the iron, which yet it will 

 not do i fince, to omit other anfwers, 

 the whole body of the File being 

 moved to and fro 5 the fame parts., 

 that touch the iron this moment, 

 pafs off the next i and befides have 

 leafure to cool themfelves by com- 

 municating their newly received A- 

 gitation to the air before they are 

 brought to grate again upon the iron, 

 which*, being fuppofed to be held im- 

 moveable-, receives almoft perpetual 

 ftiakes in the fame pl$ce* 



We 



