harmonium

noun

1. A small keyboard instrument that consists of a series of reed pipes, which sound when one of the keys is pressed to open a valve that allows air to pass through.

   “Pianos, melodiums, harmoniums, eolinas, &c. too dear at any price.”

   “The only other man was a little grey-headed fellow with a pleasant face and quick, twinkling eyes, who sat at a harmonium in the corner.”

   “They were a grave and reverend seignior in a frock coat, a lady sitting at a portable harmonium, and a chinless youth toying with a crucifix.”

   “It [Troutbeck] has religious isolation also, for it is several miles—and very strenuous miles in winter—from the parish church at Mungrisdale, and the introduction of the harmonium to the waiting room was due to the zeal of a vicar of many years ago who, in the absence of any other room in the village, obtained permission to use the premises for services, including Sunday School. Most of his successors have continued this self-sacrificing duty.”

2. Synonym of Hooke's atom.