He also made the first pair of bifocal glasses and invented a musical instrument called the glass harmonica and the stepladder chair. 他还制造了第一双双焦眼镜，发明了玻璃琴和活梯椅乐器。
harmonica英英释义
Noun:
a small rectangular free-reed instrument having a row of free reeds set back in air holes and played by blowing into the desired hole
