The focus of the paper is on the notion of representativeness. It is approached from three different angles. In the first section, representativeness as a (desirable? possible?) property of linguistic corpora is discussed. Then the point of view is narrowed down to the R (for ‘representative’) in ARCHER, and here in particular to the register ‘science’. In the following empirical part, a multidimensional analysis of English science texts of the 17th century is presented. It is based on a corpus which comes in equal parts from ARCHER and from other sources. The comparative analysis reveals major differences between the sub-corpora. They are interpreted in section 4 as different degrees of representativeness. The last section contains a summary and the conclusion that the linguistic structure of English science texts of the 17th century is not fully represented by a random sample of texts from the Philosophical Transactions.