ABSTRACT
The two main sources for commercial statistics are the Ledgers of the Custom House for the period 1696-1780 and the Reports on the State of the Navigation, Commerce and Revenue of Great Britain from 1772 onwards. G. N. Clark was the first modern writer to make an assault on the mass of trade statistics. The data in the government sources and in books and pamphlets may be compared for accuracy with the data given by Schumpeter and Mitchell and Deane. The trade statistics are loaded with landmines for the unwary. One of the dangers is geographical. Until 1707 Scotland was treated as a foreign country in the statistics, but after that date exports from Scotland to England which were thence exported were counted as English exports, not Scottish or British. With Playfair's publication in 1786 of his classic Commercial and Political Atlas, the broken-line and bar graph were introduced to economic historiography.
