We construct a data set of long-lived German patents of patent classes dyes (22) and dyeing (8) to measure the accumulation path of technological knowledge with respect to dyeing textiles. Using these data we show with a vector error correction model that in the German Empire inter-industry knowledge spill-over between the new chemical industry and the old textile industry created an upward circle of "endogenous growth." The increasing demand for synthetic dyes of the prospering textile firms initiated further research and development projects of the chemical firms that led to new patents and via customer consulting and customer training to additional economic benefits of the textile industry. (c) 2005 Elsevier Inc. All rights reserved.