Original oil and gas trade magazine vintage ad for JOHNSTON TESTERS, INC of Houston, TX. Double Shut-In Pressure Reading Provide More Information in Less Time Than Other Methods. First in Drill Stem Testing. Unique 1955 old oilfield petroleum industry equipment magazine advertisement. On the reverse side are small fractional page ads for CLAYTON MARK & COMPANY of Evanston, IL. America's Finest Handle-Bar O Ring Union and and ad for BOS-CO EQUIPMENT ENGINEERING & MANUFACTURING of Tulsa, OK Bos-Co Friction Type Starter for Horizontal Engines. Unique 1955 old petroleum industry magazine advertisements.