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.