( ( Charging ( an Electroscope ) ) ( by ( Contact ( -LRB- ( conduction -RRB- ) ) ) ) )
(ROOT (S (VP (VBG Charging) (NP (DT an) (NN Electroscope)) (PP (IN by) (NP (NP (NN Contact)) (PRN (-LRB- -LRB-) (NP (NN conduction)) (-RRB- -RRB-)))))))
Charging an Electroscope by Contact (conduction)
(ROOT (S (NP (DT A) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN electroscope)) (VP (VBZ is) (VP (VBN used) (S (VP (TO to) (VP (VB study) (NP (NN charge))))))) (. .)))