A proportional gas-counter of about 21. volume, within a castle of 5 tons of zinc, enclosing in turn an anticoincidence shield, has been used to make radiocarbon assays of highly purified carbon dioxide at a pressure of 2 atm. A net contemporary count-rate of 27 counts per minute has been secured with a constant background rate of 25. The chief features of this apparatus and of the combustion technique are briefly indicated. The radiocarbon assays have been employed to provide age determinations from a series of peat samples secured from a dry peat-bog at Scaleby Moss, Cumberland. The whole peat sequence has been pollen-analyzed and each radiocarbon sample is very exactly referred to a major zone boundary in a zone sequence which extends from the Late-glacial period continuously through almost the whole of the Post-glacial period. The dates obtained have been based upon an estimated half-life for radiocarbon of $5568\pm 30$ years. The errors of determination are of the order (1 S.D.) of $\pm 150$ years. The results are satisfactorily self-consistent, contiguous samples have closely similar dates, and the whole series of dates follows the stratigraphical sequence. It is shown that at Scaleby Moss the Late-glacial/Post-glacial boundary was about 8300 B.C.; the Boreal/Atlantic boundary at about 5000 B.C., and the Sub-boreal/Sub-atlantic boundary at about 3000 B.C. The other zone datings conform with this sequence. This evidence goes some way to establish the synchroneity of the major zones on both sides of the North Sea and indicates the suitability of the method for resolving this type of Quaternary historical problem.