600 
Trmisactions of the Boyal Society of South Africa. 
in the same time that the pendulum takes to make one-half of an oscillation, 
Jience he is enabled to find " g." 
The time of vibration is then varied by moving b along the length of the 
pendulum and a second set of observations recorded. 
nil 
T T 
Fig. 1. 
Record of BesuUs ohtained hy Elementary Students. 
Cand. I. ^ = 984, 981, 1003. 
II. , 
977, 991. 
III. , 
994, 986, 1030. 
IV. , 
, 993, 1035. 
y. 
, 991, 966. 
YI. 
, 976, 981, 981. 
VII. 
, 971, 987, 980. 
VIII. 
, 964, 979. 
The best results are naturally obtained when the time of vibration is 
