AO has definitely been around a long time. AO wasn't the one to develop this gauge though. It was a relative Reuben Smith who started his own company(after working for AO), Smith Meter Company, and patented the early Badger meter as well as other devices related to meters. It was later bought by AO Smith.

Here's a great history on Smith Meter Co which ties together AO Smith's steel history mentioned by Jack.

Smith Meter Company history



Collecting anything keeps you young at heart!