Book excerpt: Ours is an age of science and technology, based on precision instruments. The first such device to strengthen our feeble human senses in our striving to comprehend the strange and elusive universe around us was the telescope. Cornelis de Waard, in his "De uitvinding der verrekijkers" (The Hague, 1906), had uncovered many new documents bearing on the genesis of the telescope. Van Helden began this project as a translation of de Waard's study. However, Van Helden decided that the profession and de Waard's memory would be better served by a collection and translation of all the relevant primary sources named in his study. Contents of this volume: Intro.; The Background; Between Porta and Lipperhey, 1589-1608; and Documents. Illus. Reprint.