<<...porcelain mantles...>>

Never seen one of those. The kind I'm familiar with come as silk, which you burn after installation, leaving a fine net of ash. At any rate, I would guess that to "turn up [or down]" the lamp comes from your gas lamps, or from kerosene lamps.

As to Dr. Leary, I only ask because he promised to write and there were those who were watching for it. I am, incidentally, neither follower nor critic of his.