From old cut sheets I still have, circa 1970. This sheet was probably originally printed in 1950.
[from page 2]
"You never know when your next fire will be. You know that property and lives will be in danger then. That moment will call for immediate action. You will have to get your firemen together and then get them and their appiratus to that fire without one lost moment. You will have a vital need for an efficient fire alarm that will not fail you. Can you afford to rely on inadequit equipment, something new onthe market, or of cheap quality-- when you know that for more than 40 years Sterling Siren equipment has been rendering continuous unfailing service all over the world?"
Description of the Pull lever control box (hook switch)
"This is a self-winding pull lever type fire alarm box with 4 holes by which it may blow the siren 3, 6, 9, or 12 timed blasts up and down the scale. Just pull the lever down to the stop and let go. No further action is required."