From the March 20, 1929 Brooklyn Daily Eagle:

“Artificial fireflies the size of turkeys which will give off brilliant perpetual light without the vexation of meters, monthly bills and repairs were forecast last night in an address on ‘Living Lamps’ before the American Institute in Cooper Union by Dr. E. Newton Harvey, professor of psychology at Princeton University.

And whereas the firefly of nature only flashes, burning up the tiny amount of ‘oil’ in its lamp and then staying dark again until it has reformed its ‘oil,’ the robot firefly would be so contrived as to give a continuous glow, reforming a part of its ‘oil,’ which is technically called ‘luciferin,’ while it was burning the rest, this being an incessant process.”