It does not seem possible at this date to enumerate all the maps which might properly be called the special work of Blaeu, and it is doubtful if it could have been done in Blaeu’s day, since he so often borrowed here a little and there a little which he incorporated in his maps. Reference has before been made to the practice of map makers borrowing one from the other, sometimes more, sometimes less, without credit. Not all of Blaeu’s maps are signed, and but comparatively few of them are dated. He did not consider it essential always to employ the same name when affixing his signature. Sometimes he gave his name as Guilielmus Janssonius Blaeu, Guil. Jansz. Blaeu, Guiljelmus Blaeuw; sometimes as Guil. Jansz. Alcmar, Guilielmus Janssonius Alcmarianus; sometimes as Guiljelmus Caesius, or G. J. Caesius, in which, in accord with a practice of the time, he had classicized his name Blaeu; sometimes the name is coupled with that of the son as Guil. et Johan. Blaeu, and on certain maps we find the names J. or Joan. Blaeu, Johannes et Cornelius Blaeu, maps which were wholly or in part the work of the sons, but were drawn after the manner of the father.
Next to his terrestrial globe maps of 1599 and 1602, his oldest known map is that of 1605, here issued in facsimile, and described below. His “Nywe Paskaerte” of 1606, of which but few copies are now known, appears to have been the first which he especially designed for navigators. Baudet gives a somewhat enthusiastic description of a copy of this map printed on parchment, which at the time of his writing was in the possession of Mr. Tiele.[23] It is drawn with the west at the top, having a width of 76 cm. and a breadth of 59 cm., extending from 25° 30′ to 75° north latitude, or from the Canary Islands on the south to the Beeren Island on the north, from Terceira on the west to and including the Ionian Islands on the east. In a cartouche at the bottom of the map is the following inscription, given here in free translation:[24] “Willem Jansz. to the kind reader: In this map, dear reader, you will find all the sea coasts of Europe carefully drawn by Cornelius Doedsz. of Edam, according to true directions and elevations, except for the Mediterranean, in which the author has purposely omitted the elevations from Malta eastward, and has only given direction, according to our common Dutch compasses, which, in the vicinity of Candia and Cyprus point a little too much toward the northwest, as is shown by the fact that Malta, the south shore of Candia and of Cyprus are all situated in latitude 36°, although it is impossible to reach them sailing west-east, as this map clearly shows.” To the right of the above inscription we read: “Ghedruct t’ Amsterdam bij Willem Janssoon op’t Waeter inde Sonnewijser,” and to the left, given here in translation: “Since on account of the limited space the entire Mediterranean Sea could not be given, we have therefore decided, for the use of seamen, to add also the part from the coasts of Barbary, Sicily, and Malta, passing the Grecian Islands, Candia, and Cyprus to the coast of Syria.” Of the two small inset maps, one represents the Azores, the other the Beeren Island and the west coast of Spitzbergen. The eastern part of the Mediterranean, Greece and the Ionian Archipelago, the coast of Asia Minor and Syria, have been placed in the Sahara Desert. Longitude is not indicated, but latitude is given on the border, each degree being divided into thirds. In this map northern Europe is brought too far to the west, and, in accord with the general representations of the time, the Mediterranean is given too great an extent in longitude. The errors in latitude are comparatively insignificant. As one of the first examples of the work of Blaeu’s printing house, it is deserving the special mention given above, particularly so by reason of the distinctness of its boundary lines, the excellent form of its letters, and the care with which geographical details have been indicated.
Interior of Tycho Brahe’s Observatory at Uranienburg
From Le Grand Atlas
A resolution of the States General dated April 25, 1608, gives us the information that to Willem Jansz., map maker of Amsterdam, the sum of 200 gl. is to be given for the dedication and presentation of a book of sea charts, entitled “Het Licht der Zeevaert,” which lays down the coasts and harbors of the Western, Northern and Eastern Seas. In this we appear to have first reference to Volumes I and II of an important work by Blaeu, of which work a third volume appeared in 1621, protected by an octroi of the States General for six years, expressed in a resolution bearing date August 13, 1618.[25] This resolution of the States informs us that to Willem Jansz., a citizen of Amsterdam, an octroi is granted for the period of six years, to make, print, and publish in the United Netherlands, the third part of his book entitled “Het Licht der Zeevaert,” containing a description of the sea-coasts of the Mediterranean Sea. Copies of the first two volumes, printed in accord with the indication contained in the resolution referred to above, that is, in 1608, appear not to be known, but there exists a French edition of 1619, bearing the title “Le flambeau de la navigation ... Chez Guilliaume Jeansz. demeurant sur l’eau, à l’ensigne du Solaire Dore. l’An 1619,” which title is often found in the volume pasted over an original Dutch title dated 1620. In translation this Dutch title, being practically the same as that in French, reads, “The Light of Navigation in which are plainly drawn and described all the Coasts and Harbours of the Western, Northern, Eastern and Mediterranean Seas. Also many countries, islands and places of Guinea, Brazil, East and West Indies. Partly taken from the works of the best writers on marine matters [as Lucas Jansz. Waghenaer and others] but improved through the writings of experienced seamen, and by making use of their statements and explanations; enlarged by many new descriptions and maps. All divided into four books, each volume having its own index. Hereto have been added [besides a course in the art of navigation] new tables of the declination of the sun, derived from the observations of Tycho Brahe, and calculated from the meridian of Amsterdam. Also new tables and instructions in the right use of the Pole Star and other Stars, for the benefit of all navigators.” In 1627 the Dutch edition seems to have been issued by “Jan Janssoon wonende op ’t water,” the first part being dated 1626, and the second part dated 1625.
In the dedication of his third volume to the States General and to Prince Maurice, a dedication dated September 1, 1618, there is to be found a statement by Blaeu which shows his own opinion of the importance of the first two volumes. He writes he is “assured without boasting that this third volume will be as useful as the two preceding, containing the description of Eastern and Western Navigation, of which Your Honorable Body [States General] and Your Excellency [Maurice] at other times have had sufficient proof from trustworthy certificates of well known navigators, and also from the statements of the famous pilot Lucas Waghenaer.” To have from Lucas Jansz. Waghenaer a favorable criticism concerning a work which was destined to be considered superior to his own, is of no little importance. Blaeu further acknowledges in his introduction the influence of Willem Barentszoen’s maps upon his own, for he states “to the kind reader” that “we have for some years past collected very carefully all observations and plans, by means of which we have improved and enlarged in many respects the descriptions of Willem Barentsz., whose writings have been of much value to us in this work. Besides, we have added the descriptions of all the sea-coasts in the east which were not laid down by him, as of the islands of Candia, Cyprus, the coasts of Syria and Egypt, and also of the Greek islands; and how one in this way can sail even to Constantinople; and we have put this all together.” “The uses of this Book” he sets forth in six brief introductory chapters, in which he treats of “1—The difference between the Dutch and the Italian marine maps; 2—Why the compass needle is not laid directly under the compass lily; 3—Why the marine charts of the Mediterranean Sea are not drawn showing the degrees of latitude; 4—How to reckon latitude; 5—How the declination of the compass needle or the variation of the compass may be determined; 6—How to find the elevation of the sun from its shadow.”
Blaeu’s reference to the declination of the needle in this introduction is of considerable scientific importance and interest. In his day the compass makers found the needle’s declination for Holland to be from about 7° 45′ to about 8° 26′ eastward. They were, therefore, accustomed to lay the compass lily a corresponding number of degrees to the left or westward from the direction in which the needle pointed that this lily might turn to the true north. He found that in the Adriatic the declination of the needle was 0, and that in the Italian compasses the direction of the needle and of the lily agreed. Compass roses on Italian portolan or sailors’ charts, therefore, indicated no declination as the Italian compasses indicated none, and the compass lily simply marked the true meridian. As distances to be sailed in the Mediterranean were not great, latitude, therefore, was not laid down, and longitude was omitted, by reason of the fact that there was no accurate method of determining the same, consequently vessels sailed from port to port directed only by the compass. Blaeu wrote that “since the skies are there [in the Mediterranean] almost always clear, and the land high, and places are not far distant one from another, one losing sight of one part of the coast will be in sight of another part, and the majority make very little use of latitude. The seamen and those who have navigated these parts have not taken into consideration the latitudes, and follow only general direction.” This being Blaeu’s observation, which is practically taken word for word from Barentszoen’s introduction to his “Caertboeck,” one would not, therefore, expect to find either parallels or meridians laid down on his maps. He gives only compass roses and direction for sailing in accord with the Dutch compass. On the maps of Barentszoen, which maps Blaeu closely followed in many respects, the directions for sailing are given in accord with the Dutch and with the Italian compasses. Blaeu could not have followed a better master in plan and purpose, and while not always indicating just what he borrowed, he seems to have been inclined to give adequate praise to the work of his predecessor. It cannot be without interest to cite here a brief word from Barentszoen’s introduction to his “Caertboeck,” as indicating his spirit and method. He says “that not only being urged by my many good friends, but also feeling inclined myself to do so, since I always have been accustomed from my boyhood up to draw as many maps as I found it possible to draw of the countries which I visited, or around which I sailed, giving the seas, the waters and the directions, I have decided to publish certain maps of the sea-coast of the Mediterranean Seas [which I have collected for some years past] into book form, for the use and the benefit of all navigators, and persons interested in navigation. In part, I describe what I myself have seen on my journeys, in part what I have learned from other experienced navigators and pilots, who have sailed through the Strait of Gibraltar to Italy and the surrounding countries. And this I have carefully arranged, showing all harbors, roads, bays, courses and directions; giving myself a great deal of trouble, and incurring a great deal of expense. Since I did not like to rely alone upon myself, I invited to my home several seamen and pilots, who sailed the Mediterranean Seas, with whom I have communicated about my work. I made corrections whenever I found that their observations had been more exact than my own, that it might not seem as if I, being proud, intended to make a name for myself, and as if I had done this work carelessly, but that it should be clear I had gone to much trouble.”
A resolution of the States General, dated March 9, 1623, granted to Willem Jansz. Blaeu, for a period of ten years, the exclusive right to print and publish a work referred to in the resolution as “een compendium van den Zeespiegel.” It appears, however, that this was not issued until 1625, and under the title “Tafelen van de declinatie der Sonne, ende der voornaemste vaste sterren, Mitsgaders van ’t verscheyden gebruyck der Noordsterre Nieulycx, allen Zeevaerenden ten dienst, ghecalculeert door Willem Jansz. Blauw,” or “Tables of the declination of the sun and of the most important planets with the different uses of the North Star calculated anew for the use of all navigators by Willem Jansz. Blauw.” On the title-page appears a representation of the cross-staff and the astrolabe, with the imprint “t’ Amsterdam By Willem Jansz. Blauw in de guide Sonnewyser, Met privilegie, Anno 1625.” The statement is made in the preface that “from the exact observations of Tycho Brahe, we have calculated new tables of the declination of the sun.” These same tables are to be found in the Zeespiegel of 1627, and were intended to replace the old tables of the “Nieuw Graetbouck” of the year 1605.
A second privilege granted by the States General, dated March 9, 1623, as the preceding, gives us the first word concerning another work by Blaeu intended especially for the use of seamen. This work, apparently not issued until the following year, though a copy dated 1624 does not seem now to be known, bears the following title taken from the issue of 1627: “Zeespiegel, Inhoudende een korte Onderwysinghe in de Konst der Zeevaert, en Beschryvinghe der Seen en Kusten van de Oostersche, Noordsche end Westersche Schipvaert. Wt ondervindinghen van veel ervaren Zeevaerders vergadert, en t’ samen ghestelt. Door Willem Jansz. Blaeuw Tot Amsterdam. Ghedruckt by Willem Jansz. Blaeuw, in de vergulde Sonnewyser 1627. Met Privilegie voor thien Jaren”; or, “Mirror of the Sea, containing brief instruction in the art of Navigation, and a description of the seas and coasts of the Eastern, Northern and Western Navigation. Collected and arranged from the experiences of numerous Navigators. By Willem Jansz. Blaeuw, At Amsterdam. Printed by Willem Jansz. Blaeuw, in the gilded Sun-dial, 1627. With a privilege for ten years.”
Blaeu figures his declination tables from the years 1624, 1625, 1626 and 1627, on a parallel of the earth from the meridian of the west point of England, since this longitude was most frequently used by the Dutch navigators in sailing the Channel, as well as in sailing the coasts of France, Portugal or Spain. The work is divided into two parts, the first being a short treatise on the art of navigation, and the second a collection of maps or sea charts. We have in this work a striking illustration of the lingering influence of Ptolemy, for he takes as a basis of many of the ideas he presents the work of Ptolemy. The book does not undertake, as Baudet points out, to add to or improve the methods of defining geographical location. It does not undertake to correct what were the known errors in his day. He treats in his first part of the several spheres; he presents what he considers to be acceptable proof that the earth is in the center of the universe, as the stars appear at all times to be of the same size, in whatever part of the heavens they may be; he explains the construction and the use of the cross-staff by means of which the observer determines the altitude of the sun; he points out that in determining latitude by observing the altitude of the Pole Star, 2° 42′ should be taken as the distance from the star to the pole; he discusses the subject of atmospheric refraction, basing his observations on those of Tycho Brahe, which discussion is of special interest since it sets forth the attitude of seamen of that day toward this subject, and the difficulty they had in meeting it by reason of the imperfect instruments with which they made their calculations.