Island of Hveen, showing the location of Uranienburg. From Le Grand Atlas
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We have but little direct information concerning Blaeu’s sojourn at Uranienburg. It appears certain that he passed at least two years with Brahe, engaged the while in study and in the construction of mathematical and astronomical instruments. May 21, 1596, the day of the young Hollander’s departure for his native land, Brahe made the following entry in his day-book, which book may be found in the Imperial Library of Vienna, “Abiit domum in Hollandiam, Vilhelmus Batavius cum per integram hyemen his fuisset,” and by Gassendi we are told that Guilielmus Janssonius had been with Tycho for two years, although he does not make it certain that it was for two consecutive years. That the relations between the two distinguished scientists continued to be of the most friendly character long after the date given above is very certain, as not a few of those who in later years in praising Blaeu’s scientific attainments refer to him as “the pupil and longtime friend of Brahe,” yet neither of them appears in his writings to have made more than a passing allusion to their relations.[5]
It cannot be doubted that Blaeu owed to his abode on the island of Hveen the real foundation of his scientific knowledge, both in the field of geography and of astronomy, as well as his knowledge of the construction and the skilful use of mathematical instruments. We have reason for believing that a number of the instruments which served the great astronomer in his investigations, were the work of Blaeu, and it is an interesting fact, as we know, that Brahe’s observations, here made, formed the basis for Kepler’s calculations, leading him to the discovery of the laws which immortalized his name.
It was perhaps late in the year 1596, or early in 1597, that Blaeu returned to Amsterdam where he soon established himself as a maker of mathematical instruments, of maps and of globes, and as an engraver and printer.
Before the close of the seventeenth century, the Netherlands had moved into the first rank of European states in which the art of engraving and of printing flourished. Nothing perhaps contributed more to this end, especially in the north, than the freedom which there prevailed untrammeled by the restraints of the Index.
As for the particular art of map engraving and map printing, the work of Mercator, of Ortelius, of Waghenaer, had centered the attention of those interested in this field upon the Low Countries. As early as 1541, not to mention his work of the preceding decade, Mercator issued his terrestrial globe gores, which mark a decided advance in the art of map engraving, and this was followed by his large map of England, of Europe, and of the World, the latter setting forth the new method of projection since known as Mercator’s projection. Ortelius’s great work of 1570, with its numerous succeeding issues, Waghenaer’s Mirror of Navigation of 1585, and Mercator’s book of maps of 1585, for which collection as a title the name Atlas was first used, were superior productions, models for those who followed closely within the same field.
Blaeu acknowledged these men to be his masters, though, as was also frequently the case with other map makers and map engravers of his day, he occasionally forgot to assign proper credit to those from whom he borrowed in the cartographical work that issued from his press.
We are told that Tycho had given to Blaeu a copy of his astronomical observations before their publication, that this copy was carried to Amsterdam, and that on the record contained therein the latter began the practice of globe making. The implication contained in this reference is that his first work as a globe maker was the preparation of material for a celestial globe, but no such globe of his is known bearing date earlier than 1602. His first dated work appears to have been a terrestrial globe of the year 1599. It was as a maker and vender of mathematical instruments, as a collector and close student of maps geographical and astronomical, he probably found his chief employment during the first years after his return to the Netherlands. There is good reason for thinking that from the first he prospered in his undertakings, and that he was soon in a position to establish an independent business. It may be inferred from incidental references that it was not long after 1600 he was in his own fully equipped house engaged in the business of engraving and printing.