Blaeu’s charts are drawn on a plane or cylindrical projection, although the projection of Mercator had been known for more than half a century. This fact seems to suggest the idea that in publishing his book he had not so much in view the question of the advance of the art of navigation as to meet a desire for a work in agreement scientifically with the knowledge of seamen of his day. In point of accuracy, Blaeu’s charts in this work are wanting much, but we must not forget the imperfect methods employed in his day for obtaining geographical location. If accuracy was wanting in the land maps, much less could we expect to find accuracy in the marine charts. Seamen in part were accustomed to estimate longitude and distance from change in latitude, and the direction in which they sailed. The speed of a ship was often estimated from the size and the number of sails used. It was not until about the middle of the seventeenth century that the log was brought into common use, consequently Blaeu makes no reference to it. It is interesting to note that a somewhat similar instrument was employed about the middle of the sixteenth century for measuring the angle which the axis of the ship made with its track as observed on the surface of the water. In his “Spieghel der Zeevaert” of 1584, Waghenaer states that for measuring this angle, “it is necessary to let the plumb line log behind with a piece of wood attached or otherwise.” A comparison of the maps of Blaeu with those of his distinguished predecessors, Lucas Jansz. Waghenaer and Willem Barentszoen, warrants our assigning to him first place, both in point of execution and in the nearer approach to correctness in his drawing. John Blaeu, in his Atlas of 1664, referring to the maps of Waghenaer and Barentszoen, says that “my late father not only greatly improved both of these, but also enlarged them for the benefit of navigation, adding to them so much that was lacking that his may justly be called a new work.”
In 1646, John Blaeu printed a fourth part of the Zeespiegel, bearing the title “Vierde deel der Zeespiegel, inhoudende eene beschryvinge der See-havenen, Reeden, en Kusten van de Middelandsche Schipvaert. Uyt ondervindingen van vele ervaren Zeevaerders by een vergadert, en t’ samengestelt, door Willem Jansz. Blaeu, t’ Amsterdam. Gedruckt by Johan Blaeu, op ’t Water, in de vergulde Zonnewyser. 1646,” or “Fourth Part of the Mirror of the Sea, containing a description of the Harbors, Roadsteads, and Coasts of the Mediterranean Navigation. Collected from the experiences of famous Navigators, and arranged by Willem Jansz. Blaeu at Amsterdam. Printed by John Blaeu on the Water in the gilded Sun-dial, 1646.” There is included in this fourth part the third part of the “Licht der Zeevaert” of 1621, with the arrangement of the contents and the size of the volume somewhat altered. That which is true of certain map publishers in this day, in their attitude toward their own publications, was true of the publishers of these Willem Blaeu maps after his death. So long as there were publishers for them, it was not thought to be necessary to improve them, especially so since John Blaeu, who had succeeded his father in charge of the business, had taken up what he thought to be more profitable printing than the issue of charts for seamen. Other publishers, after the middle of the century, were entering the field, and the Blaeu marine maps in course of time came to be regarded as obsolete.
What we may call his first Atlas of land maps appeared in 1631, with the title “Appendix Theatri Ortelii et Atlantis Mercatoris.” It contains maps which had been previously issued, some by himself, many by other map makers, while in numerous instances he left it difficult to decide both date and origin. We know that as early as 1605 he was issuing maps and charts in single sheets, following the example of Ortelius, Mercator, Judeus and others. Baudet, it may be noted, expresses himself as being unable to decide whether the World Map of 1605, referred to in the resolution of the States General of the 23d of April of that year, was of this character, not knowing of the existence of a copy of the map here reproduced in facsimile from that belonging to the Hispanic Society of America. “My belief,” he says, “is that the World Map of 1605 is the Nova totius terrarum orbis geographica ac hydrographica tabula, auct. Guiljelmo Blaeuw,” according to Mercator’s projection, to be found in the “Toonneel des Aerdrycx.”[26] Not unlike Ortelius, Blaeu often selected for addition to his own original land maps the best which he found it possible for him to use, redrafting them on a scale to fit his own Atlas. In general, he greatly improved their character by his own re-engraving, giving us maps of superior excellence in line, in letter, and in ornamentation. He was not unmindful of the high favor in which the Atlases of Ortelius and of Mercator were held. He, therefore, shrewdly calls attention to their work by giving to his own a title which suggests a connection, though in fact he was scarcely justified in calling his Atlas an Appendix to Ortelius and Mercator. This Atlas of 1631 contains one hundred and three maps, with text in Latin usually printed on the back of each. Seven of his maps are dated, twenty-seven have the names of the original maker, and many of them are signed Guilj. Blaeu, G. J. Caesius or Guiljelmus Janssonius et Joannes Blaeu.
He begins his preface with much praise of Ortelius and Mercator, observing that Mercator died untimely for his work, after finishing Europe except Spain, and he assumes it as his task to publish an Appendix to the Atlases of these great men. He states that his Atlas will contain maps of countries already drawn by them, but he promises to improve them. That he did improve not a few of them is made evident by a close comparison, yet he left many features uncorrected, which easily could have been brought to date.
He often intimated to his friend, W. Schickard, his ever present desire to improve his maps, in which references we find the first promises of his work issued in 1634 under the title “Toonneel des Aerdrycx.” In a letter dated Amsterdam, November 22, 1633, he tells his friend of his preparation for this new Atlas,[27] expressing the hope that he would be able to complete the first part during the winter, and accepting from him an offer for a new map of Würtemberg, for which he was ready and willing to pay the price asked. This map he thought would add much to his maps of Germany. December 6, 1633, he writes again to Schickard: “The esteemed gentleman, Hugo Grotius, has informed you that I am planning a new Atlas, and that a considerable part of it is already completed, in addition to my Appendix Theatri Ortelii et Atlantis Mercatoris, which has been published, so that I will be able to issue yet this winter two parts of reasonable size, one part of which will contain maps of upper and lower Germany, and as I should like to add this map of Würtemberg which you have drawn, and which you have promised me, I therefore wish to postpone the publication a little longer. You write that this map of Würtemberg which you have drawn on twenty sheets can be reduced to four of common size. If, however, you deem it better to make use of more sheets, you may follow your pleasure. Whatever your decision, I will pay the price which you ask for it.” On January 12, 1634, Blaeu writes Schickard again: “I am pleased to learn you agree with my opinion in regard to the number of maps. It is my intention to place two or three provinces on one sheet, but it will be necessary, however, to leave some open space in which I can write the titles of the maps, arms of the country, and the scale of miles. Do not let this worry you, however, but follow the divisions which are most easy for you. In the case of maps so carefully drawn, it seems to me the larger the number, the better it will be. Forests, buildings, etc., may be but roughly marked. If you will give the size and exact location, I will take care that the emblematical figures are properly represented”; and he adds that “in order to make sure that the completed work is well done, I shall let you correct the plates one at a time.” Somewhat later Blaeu writes again that “I shall give especial attention to the engraving of the plates, printing lightly from them at first, in order that changes may be made before the final engraving is done.... Take as much time as you may need, and in case you are unable to finish them during the summer, you may also have the winter.” June 24, 1634, he writes to Schickard: “I have published the first part of my Atlas, containing one hundred and sixty maps, with descriptive text in German, translated from Latin. In the Fall I shall publish the Latin, French and Dutch texts,” these titles being, respectively, “Theatrum Orbis Terrarum,” but dated 1635; “Le théâtre du monde ou nouvel atlas,” but issued in 1634; “Toonneel des Aerdrycx,” 1634. The arrangement and number of maps in the several issues do not agree, but in the main features they are the same. The “Toonneel” may be considered an enlargement of his “Appendix” done in practically the same manner, but with the addition of numerous details, and ornamented with additional illustrations. That he borrowed from the “Nieuwen Atlas” of Joannes Janssonius and Henricus Hondius becomes evident in a comparison of the descriptions of “Germany,” the “Netherlands,” and of certain other parts.
The “Appendix” and the first two parts of the “Toonneel,” published by Willem Blaeu and his son John, may be regarded as the beginning of the large Blaeu Atlas first issued in 1662 in eleven volumes, a work of unsurpassed excellence; indeed, we may refer to it as the foremost atlas produced by the great Dutch atlas makers of the seventeenth century. Its completion and issue, after the death of the father, Willem, places it therefore without the scope of this sketch, yet as he had contributed so much to insure its success by his own early activities, a word of reference to it is here fitting. Editions of this work appeared in rapid succession in the Dutch, the French, the Latin and the Spanish language, the number of volumes being either nine, ten, eleven or twelve in each edition, varying otherwise but little in the essential features. As numerous copies of the work were printed in each edition, it is therefore not a publication which can be called rare even in this day. Most of these editions were printed from the superior type and copper plates of the Blaeu printing house, and on paper of fine quality; some were issued in costly bindings, having their maps, coat of arms and emblems of states and of royalty exquisitely colored. Copies of the atlas were especially prepared for rulers and for statesmen of renown. We are informed that to Admiral de Ruyter an especially fine copy was presented after the two days’ battle of 1666, and that in the name of the States General a copy bound in royal purple was presented to the Sultan Mohammed IV, with which he was so well pleased that he ordered its translation into the Turkish language.
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In Blaeu’s day globes were held to be of the highest value as aids in the study of geography and astronomy.[28] Seamen engaged in transoceanic navigation counted on a terrestrial and a celestial globe as essential to a navigator’s complete outfit of instruments, and as Blaeu was especially desirous of making his scientific knowledge serve the cause of navigation, it was but natural that he should turn his attention to globe making.
Among those skilled in the art of globe construction in the late sixteenth and the early seventeenth century, the Low Countries could claim such distinguished men as Gerhardus Mercator, Jacobus [Florentius] van Langren and Arnoldus [Florentius] van Langren, father and son, Jodocus Hondius and Guilielmus Jans. Blaeu, and none of these was more skilful than the last named. Both for the number constructed and for the quality of the work, his globes are cartographical and astronomical treasures of the first value.
