282 Experiments on the Vibrations of Pendulums. 



With spring No. 3, and effective length -92 inch, the following 

 results were obtained on two consecutive days : — 



Weight. Arc. Rate. 



41b. loz. 2° 15' -2s. -5 



2 2 1 39 -2-8 



Reducing the effective length of the spring to -80 inch, the fol- 

 lowing results were obtained on consecutive days : — 



Weight. Arc. Rate. 



41b. loz. 2° 9' OS- -0 ? 



2 2 1 



4 1 2 



2 2 1 



4 12 



Hence, with either of these lengths of this spring, the rate does 

 not appear to be perceptibly influenced by the extent of the arcs 

 of vibration. In fact, the vibrations of the pendulum may, for all 

 practical purposes, be considered as isochronous. 



The effective length of the spring was then increased to -92 

 inch, and the following results were noted, without maintaining 

 power : — 



Arc reduced from 2° to 1° in 2h. 26m. Os. 

 Do. do. 2 12 25 45 



Do. do. 1 J 2 37 



Do. do. 10 2 36 40 



On three other occasions, with the same spring, and effective 

 length, -92 inch, the following comparative results were ob- 

 tained : — 



Weight. Arc. Rate. 



41b. loz. 



2 2 



4 1 



2 2 



4 1 



4 1 



Showing that even with different lengths of this spring, the 

 vibration may be considered as isochronous, with considerably dif- 

 ferent arcs of vibration ; and also that with this spring, a greater 

 arc of vibration is produced with the same maintaining power, 

 than with any other spring that has been tried. 



Spring No. 4 was next applied without maintaining power. 



