Zither
2 of the 7 encyclopedias on this shelf carry an entry for Zither. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
or ZITHERN (tsit' urn), a development of the musical instrument known to the Greeks as cithara. In the early part of the 19th century it became a favorite with the peasantry of the Styrian and Bavarian Alps, and was introduced into England about 1850, chiefly by Herr Curt Schulz . The zither consists of a resonance box, with a large circular sound hole near the middle; the strings, 32 in number , in some cases in creased to 40 and even 46, being made of steel, brass, catgut , and silk covered with fine silver or copper wire, and tuned by pegs at one end. Five of the strings are stretched over a fretted keyboard, and are used to play the melody, the fingers of the left hand stopping the strings on the frets, the right-hand thumb , armed with a metal ring, striking the strings, which are tuned in fifths, and have a chromatic range from c in the second space of the bass staff to d in the sixth ledger line above the treble. The remainder, called the accompaniment strings are struck by the first three fingers of the right hand, and, as they are not stopped, produce only the single note to which they are tuned. While playing, the performer rests the instrument on a table with the keyboard side nearest to him. The viola zither, in which the resonance box is heart-shaped, is tuned like the violin, and is played with a bow. The form of the instrument is like that of the viola, but the body rests on the lap of the seated player, while the head is placed on the edge of a table.
Aiton's Encyclopedia (1910)
or Cithern, a stringed musical instrument. In medieval times it was a modified form of the lute or guitar, and like a guitar was held vertically. The modern zither is more like a four-sided harp. It is laid horizontally on a table. There are thirty to forty metal strings which are played or twanged with a plectum of ivory or horn. The length of the strings is varied by stopping on a fret-board.