"Rifle" lights

[Ralph Keyser]

I've been reading Joe Walker's autobiography "The Light on Her Face", and he has refered a couple of times to using rifle lights. I'm just curious if anyone knows what type of lights these might have been. This would have been a term from the 1930's or 40's in LA.

 

The book, which I think is out of print now, is a fascinating look at the early days of the film business in LA.