Measurements of samples of known age have been undertaken in this laboratory since its beginning in 1951 when it was found that modern wood samples taken from the outer rings of young trees did not afford a basis of counter calibration consistent with archaeologically dated samples (Ralph, 1955). This depletion was explained by Suess (1955). Subsequent measurements of samples representative of the early Egyptian dynasties, however, revealed that even with the counter calibration corrected for the modern depletion, there was a discrepancy between C14 dates and the early Egyptian chronology (Arnold and Libby, 1951; deVries, Barendsen, and Waterbolk, 1958; deVries and Waterbolk, 1958; Barker and Mackay, 1959, 1961; Ralph, 1959; Damon and Long, 1962). Obviously, there was, and still is, a need to find samples of known age for this time range. Dendrochronology may ultimately provide the answer, and in the meantime tree-ring dated samples have afforded a means of assessing the atmospheric C14 inventory during the last 3000 yr.