Sentence:  The measurements made with the NRL 50 - <WSD>foot</WSD> reflector , which is altitude azimuth mounted , would have shown a systematic change with local hour angle in the measured intensities of Venus and Jupiter if a substantial part of the radiation had been linearly polarized . 
Meaning of the word marked with <WSD> tags:  a linear unit of length equal to 12 inches or a third of a yard