( ( The method ) ( ( involved ( ( ( ( observing ( ( ( ( the increase ) ( in ( the ( gas pressure ) ) ) ) ( due ( to ( the helium ) ) ) ) ( generated ( in ( ( an apparatus ) ( of ( known volume ) ) ) ) ) ) ) , ) and ) ( applying ( ( Boyle 's ) law ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN method)) (VP (VBD involved) (S (VP (VP (VBG observing) (NP (NP (DT the) (NN increase)) (PP (IN in) (NP (DT the) (NN gas) (NN pressure))) (ADJP (JJ due) (PP (TO to) (NP (DT the) (NNP helium)))) (VP (VBN generated) (PP (IN in) (NP (NP (DT an) (NN apparatus)) (PP (IN of) (NP (VBN known) (NN volume)))))))) (, ,) (CC and) (VP (VBG applying) (NP (NP (NNP Boyle) (POS 's)) (NN law)))))) (. .)))
The method involved observing the increase in the gas pressure due to the helium generated in an apparatus of known volume, and applying Boyle's law.
(ROOT (S (PP (IN From) (NP (NP (NNS observations)) (ADJP (RB as) (JJ simple) (PP (IN as) (S (VP (VBG blowing) (PRT (RP up)) (NP (DT a) (NN balloon)))))))) (, ,) (NP (PRP it)) (VP (VBZ is) (ADJP (JJ clear)) (SBAR (IN that) (S (S (VP (VBG increasing) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NN gas)))))) (VP (VBZ increases) (NP (DT the) (NN volume)))))) (. .)))