Patents are about solutions to problems, and the patent collection contains an interesting history of solving the problems with Christmas Tree Illumination. From 1867 unitl the advent of electric Christmas lights, a surprising amount of effort was devoted to making candles safe for Christmas trees:
U.S. Patent No. 286572 (1883) Candle Holder for Christmas Trees.
U.S. Patent No. 373958 (1887) Lamp for Decorating and Illuminating Purposes