the world > matter > light > artificial light > an artificial light > artificial light defined by light-source > [noun] > oil-lamp > moderator-lamp (3)
Short for moderator lamp n. at compounds 2. Also: the mechanism which regulates the flow of oil to the wick in a moderator lamp. Now historical.
an oil lamp in which the flow of oil from the reservoir to the burner is maintained as a uniform flow by a regulating mechanism (cf. modérateur, n.).