Before turning for a reference more in detail to the publications which were issued by the Blaeu press, to a consideration of Willem Blaeu’s most important work as engraver, as globe maker, as printer and publisher of maps and navigators’ charts, a further brief word may be said touching certain general interests and activities of his, touching certain personal relations and individual characteristics, which support the conclusion that he was a man justly held in the highest esteem by men of science of his day, and that he was interested in whatever pertained to his great field of study.

Reference has been made to Blaeu’s ability as a maker of mathematical and astronomical instruments, which work claimed more or less of his attention to the end of his days. The fact, however, is a very remarkable one that from the many years of activity as an instrument maker with Tycho Brahe, and independently at Amsterdam, but one example of his should have come down to us. Vossius says that “no other scholar ever deserved so much praise as Blaeu on account of an extraordinary and beautiful quadrant, which can be seen at Leyden in the tower, where astronomical observations are being made.”[11] His reference is to a quadrant now kept in the Leyden Observatory. It is described by Kayser in his Annals of the Observatory as a wooden quadrant, with a brass rim, having a radius of seven feet.[12] In the year 1632 it was purchased from the estate of Willebrod Snellius, and may be said to have induced the founding of this observatory in the year 1633.

With the conscientious map makers the problem was ever present, how shall accuracy in space relations, accuracy in location of places on the map be attained. Ptolemy had been a guide in the earlier years of great geographical discoveries and explorations, but geographical knowledge soon extended to regions beyond those known to Ptolemy, and the inaccuracies of his records, even for those regions more or less familiar to the ancients, became very apparent. In the maps of the seventeenth century we have interestingly exhibited the tortuous advance of geographical knowledge. They do not show a steady and continuous progress toward accuracy. Information which may have been accepted as truth respecting certain regions or geographical areas, and have been recorded as such by one or by many of the map makers, would often be held as doubtful by those of succeeding years, to be accepted and rejected again in turn. Blaeu’s intimate acquaintance with mathematics and astronomy as related to geography, particularly as related to cartography, admirably fitted him for a certain leadership in this field. We have from Vossius the information that Blaeu undertook the measurement of a degree on the surface of the earth to the end that he might aid the map maker in improving his work and serve especially the cause of navigation. In his attempts to find a new and better method for terrestrial measurements, it seems probable that he anticipated the work of the great mathematician Snellius, whose results were first published in the year 1617, and to whom credit is generally given for having employed a new method of procedure based upon triangulation.[13] Blaeu’s measurements, made along the coast of the Netherlands from the mouth of the Meuse to the Texel, were never published, probably for the reason, as suggested by Vossius, that he may have distrusted their accuracy. The mathematician Picard, in his Voyage d’Uranibourg,[14] writes in the month of July, 1671, a brief word concerning Blaeu’s contributions toward the solution of problems having to do with terrestrial measurements, giving us in this word practically the only information we have concerning the matter. According to Picard, Blaeu’s measurements gave results with an error of but 66 meters, whereas for the same measurements, Snellius’s results gave an error of no less than 3880 meters. Had Blaeu more persistently carried on his studies in this particular branch of mathematical geography, his name doubtless would have been with the very first in a list of those who have made contribution to the science of terrestrial measurement and to a reform of the maps. His aim was set in the right direction, and we are safe in saying that none, in his day, made greater contribution toward the attainment of accuracy in map drawing than did he. To be able to understand the nature of the errors so common in chart making and to be able to correct the same were two very different matters, and although Blaeu was able to point out many errors, such, for example, as pertained to latitude and longitude, his maps do not indicate that he was able to overcome all difficulties. His was not the day for scientifically accurate results. Years had yet to pass before that end could be attained. To some of his errors, and to certain improvements of his, attention will be directed later. He appears to have been especially desirous, at all times, of acquiring detailed geographical and astronomical information from navigators who visited distant regions, making request of them that their observations should be reported to him. In a letter to W. Schickard, dated June 24, 1634, Blaeu wrote, “When the directors of the East India Company placed me at the head of their department of hydrography a year ago, I requested them to charge all pilots and masters who sailed for India to observe all eclipses, in whatever part they might be seen, and this has been done.”[15] His desire to be of assistance to others in giving out such information as might come into his possession is made evident by the further word in his letter to Schickard assuring him that “if observations of eclipses from India or other places on the way are sent to me, I shall be pleased to inform you of them.”

The determination of longitude, particularly at sea, remained for more than a century and a half after Blaeu’s day a most perplexing problem, a problem, however, of the greatest significance in the art of navigation, miscalculations being often the cause of most serious disasters. The rulers of the maritime states of western Europe not infrequently offered liberal reward for its solution. Philip III of Spain, for instance, promised an annuity of 6000 ducats to the one who would first devise a method for determining longitude.[16] Numerous attempts were made in Spain and Portugal, as a result of the promised reward, but the problem remained unsolved. The States General of Holland, for instance, offered a liberal reward to Plancius should a plan he submitted prove to be of value, which plan he had based upon the declination of the needle; and in the records of that body, bearing date May 21, 1601, we read that a reward of 150 pounds was promised to any one who, having made an expedition for the purpose of determining longitude and latitude, could obtain the support of six or eight sea captains that his method was of real value.[17] Blaeu often figured somewhat conspicuously as an expert in passing upon the solution of certain problems which were offered. Resolutions of the States General, for example, make mention of a plan submitted by Thomas Leamer, an Englishman residing in Amsterdam, but it appears that no satisfactory agreement could be entered into with him on his first plans, and it was, therefore, decided to submit his subsequent propositions to the College of Admiralty of Amsterdam, authorizing this body to ask for a demonstration of the new invention in its presence, to have it investigated by Willem Jansz. Blaeu and other masters in this art together with such experienced navigators and pilots as the College might see fit to choose, to examine it carefully and impartially with especial reference to its practical value, and to follow their best judgment as to the advisability of attempting to make use of the invention.[18] On July 3, 1612, the Council of the Admiralty sent word to the States General that the aforesaid Leamer had been examined, in accord with the letter of December 21, 1611, at different times, and at his request again and again in its presence, by “Willem Jansz,” and by many other persons experienced in mathematics and navigation, in order to find out the truth relative to his proposition; that they had charged the judges to examine honestly, and that it had been unanimously concluded the invention was wholly worthless.[19] It is not without interest to note that Leamer made an especial appeal to the Admiralty of Amsterdam, charging the committee with partiality and with inability to judge the case, but we are not informed that the Admiralty altered its opinion.

Taking into consideration the extensive commerce and interest in navigation of the United Provinces in this period, it does not occasion surprise that Galileo, after having offered in vain to Philip III his plan for a new method of determining longitude, should decide to present the same to the States General of the Provinces.[20] This plan he based upon his discovery in 1610 of the satellites of Jupiter and the valuable data furnished him through a study of the eclipses of these satellites. Galileo himself tells us of his negotiations with Philip of Spain, stating that the King informed him of the many inventions which had been sent to him, and which he had accepted, only to find afterward that they were of no practical value. Having been so often deceived, he had come to the conclusion that a great deal of money had been wasted, and had, therefore, decided to be more careful in future. It was not until August, 1636, that Galileo decided upon presenting his plan to the States General, as he informed Hugo Grotius, then Swedish consul at the French Court, and not until November of that year that Laurens Reael handed to the States a letter from him containing an explanation of his method, with an offer of the plan to that distinguished body. Blaeu is again chosen as one of four experts to examine and report on the invention. Galileo’s plan was well adapted for the determination of longitude on land, but because of the ship’s motion on the high seas it did not prove to be practical for navigators, though he suggested the placing of his instruments and the observer in a vessel of water on the ship’s deck, thinking thus to counterbalance the ship’s motion. By resolution of April 25, 1637, he was to receive a reward for the new method he had suggested, but it does not appear that it was paid to him.

Blaeu’s training admirably fitted him to serve his country in matters pertaining to its maritime interests, and its calls as well as its rewards for his services were not infrequent. As further proof of the confidence that his contemporaries had in his knowledge of geography and navigation, the States General of Amsterdam, January 3, 1633, by resolution appointed Blaeu map maker of the Republic, an honorable position held by him until his death, being then successively passed on to his son and to his grandson. In a resolution of October 23, 1666, we read that no house engaged in commerce will be allowed to send any marine maps to India, or have them taken by captains of vessels, except those made by Blaeu; and in a resolution of 1670 it is stated that to Willem Jansz. Blaeu, map maker in ordinary of the Company, instruction has been given to examine the journals of the pilots and to correct and improve the maps.

It is not easy at this date to determine the justice of the several complaints which we find were occasionally made by certain map makers of the Netherlands in the early seventeenth century against fellow countrymen. There was so much borrowing one from the other without credit that it would be an exceedingly difficult, if not impossible, task to give a complete catalogue of any one of the several map makers’ work. Rivalry often ran strong, and the authorities not infrequently were urged to exercise special diligence to prevent the infringement of a copyrighted plate, or one that was protected, as they at that time expressed it, by an octroi. Between Willem Blaeu and Joannes Janssonius this rivalry was particularly marked, each claiming at times an infringement by the other. Whether it was for protection against Janssonius that Blaeu in 1608 presented a special plea to the States of Holland and West Friesland, asking that he be made secure against the loss caused by pirated editions of works published by him, is not certain. He informed the States that he had given himself hope of being able to support his family in an honest way, and that he would have succeeded with God’s mercy and blessing, if certain individuals engaged in the same business had not undertaken to copy his new works, as well as his enlarged and improved works.[21] This rivalry between Blaeu and Janssonius continued for many years, involving in some degree Jodocus Hondius, the father-in-law of Janssonius. It seems probable that Blaeu’s complaint of 1608 touched in some manner his large World Map of 1605, since, as before stated, there is a striking resemblance between this and the World Map of Hondius issued about 1611, on which he must have been at work for some years, a similarity in which the very differences and slight variations cannot be without peculiar significance.[22]

If Blaeu won deserved renown through his scientific attainments, so the Blaeu press became renowned for the excellence of the work which bore its imprint. Its map engravers were among the most skilful employed in the workshops of the Netherlands, its types were unexcelled in simple but artistic form, unless perchance one may accord first place to the Elzevir press. His good work, as we know, was a spur to others, as, for example, to Hondius and Janssonius in the issue of their Atlas of 1633.

The list of works which issued from this famous printing house in so far as we have accurate information, is an exceedingly long one, and the titles include many which do not touch upon matters geographical, hence do not call for consideration in this brief sketch. We may, therefore, pass to a more detailed word concerning those works which bear particularly upon geography and navigation, to his maps and globes.

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