Original oil and gas trade magazine vintage ad for SCHLUMBERGER WELL SURVEYING CORPORATION. Main office was located in Houston, TX. Radioactivity Logging new design, completely re-engineered to give more hole data and greater accuracy. Rigid calibration system eliminates human and equipment variables, assures accurate, dependable porosity determinations. This unique 1959 old petroleum oilfield drilling equipment magazine advertisement would display beautifully matted and framed.