I recognize the name "Bristol". My memory is suggesting something they manufactured was used in Milwaukee Road electric motors and substations.
Sheet metal and supply co. - catalogue f. bySheet Metal and Supply Co https://archive.org/details/SheetMe...valves+and+gauges?q=ammonia+valves+and+gauges Handy Notes and Queries : A Manual of Useful Information of Especial Importance to Dealers in Hardware, Stoves and Tinware : Southern and Western Edition 1889 byHenry Hopkins & Co. https://archive.org/details/HenryHo...valves+and+gauges?q=ammonia+valves+and+gauges
Pittsburgh Gage & Supply Company Blue Book of Supplies : Catalogue No. 12 Pittsburgh Gage & Supply Co. 1913 https://archive.org/details/PittsburghGageAndSupplyCoCatNo12/page/n3/mode/2up?q=ashton
Power plant testing, a manual of testing engines, turbines, boilers, pumps, refrigerating, machinery, fans, fuels, lubricants, materials of construction, etc 1913 https://archive.org/details/powerplanttestin00moyeuoft/page/n5/mode/2up
I while back I ran into some paper in one of my collection boxes. It was a graph sheet, round, of a 24 hour period of electric substation activity, feed catenary. The sheet was by Bristol.
Catalogue "J" by Rundle-Spence Manufacturing Company 1922 https://archive.org/details/gri_33125000174371/page/n7/mode/2up?q=whistles Hibbard, Spencer, Bartlett & Co. General Catalogue : 1891 [Excerpt] byHibbard, Spencer, Bartlett & Co. https://archive.org/details/Hibbard...alCatalog/page/n5/mode/2up?q=3+chime+whistles
Ashcroft steam, pressure, and vacuum gauges 1920 https://www.google.com/books/editio...dq=ammonia+gauges&pg=PA50&printsec=frontcover
Illustrated catalogue of locomotives; Baldwin Locomotive Works 1881 by Baldwin Locomotive Works; Burnham, Parry, Williams & Co https://archive.org/details/illustratedcatal00baldrich/mode/2up?q=locomotive+engines
And a parts catalog for Baldwin, 1906. Baldwin Locomotive Works; 1906 by Baldwin-Lima-Hamilton Corporation. [from old catalog] https://archive.org/details/baldwinlocomotiv00bald/mode/2up?q=steam+locomotives
Ashcroft Gauge catalog 1920 https://www.google.com/books/editio...q=ashcroft+gauges&pg=PA10&printsec=frontcover