An antique rosewood  combined ruler, with a wafer signet at one end and a candle at the other end. The candle socket unscrewsand would have been used to light a candle. The candle could be used to melt wax sticks for sealing letters.
Prior to 1840 gummed envelopes didn't existI and letters were sealed using wax seals.
There is a similar example illustrated in Pinto.
It measures 24.5cm l x 1.7cm w