Noi'. 13, 1879] 



NA TURE 



4i 



established the laws of its motion in ordinary small oscil- times as long, and always in the proportion of the square 



lations. He showed that though the weights at the end roots of the lengths. In proving this he had to investigate 



of the string have no effect on the times of oscillation the motion along a slope or Inclined Plane, and it was he who 



length of the string has, that these times are twice as long first showed that whatever the incline, the speed acquired 



for a string four times as long, three times for one nine by a body moving on it depends not on the amount of 



The Le 



ground it has covered on the plane itself, but on the from point to point in it successively. The smaller these 



vertical drop between its starting p 'int from rest, and its 

 position at any moment. The pendulum moves along an 

 arc of a circle, and something very like that arc would be 

 got by drawing instead of it small chords of the circle 



successive chords become the nearer the sum total of them 

 is to the arc, and the motion of a heavy particle con- 

 strained to move down them is substantially the same as 

 that of the bob at the end of the pendulum. These sue- 



