He sketched a harp apparatus that was based on the notion, according to a letter Bell wrote to his parents, that "the vibrations of a permanent magnet will induce a vibrating current of electricity in the coils of an electromagnet."
(He; sketched; a harp apparatus that was based on the notion) (a harp apparatus; was based; on the notion) (a letter; wrote; to his parents) Context(a letter wrote,List([72, 91))):(the vibrations of a permanent magnet; will induce; a vibrating current of electricity; L:in the coils of an electromagnet)
a letter wrote,List([72, 91))
He a harp apparatus a letter the vibrations of a permanent magnet
sketched was based wrote will induce
a harp apparatus that was based on the notion
on the notion
to his parents
a vibrating current of electricity L:in the coils of an electromagnet