Forschungsberichte und Rezensionen 751 rapid and significant productivity gains in the following years. However to understand the background to this development and the role of the 1844 tariff, a wide-ranging analysis of this sector both on the Belgium and German side of the frontier would have been essential. Unfortunately this is not provided. In conclusion, therefore, Sydow has performed a useful function in initiating debate on the issue of trade relations berween Belgium and the Zollverein for this central period of the 19