What does armil mean?
The definition of armil
Ar”mil, n.
Etym: [L. armilla a bracelet, fr. armus arm: cf. OF. armille.]

1 A bracelet. [Obs.]
2 An ancient astronomical instrument.

Note: When composed of one ring placed in the plane of the equator for determining the time of the equinoxes, it is called an equinoctial armil; when of two or more rings, one in the plane of the meridian, for observing the solstices, it is called a solstitial armil. Whewell.