Schat-Kamer ofte konst der stuurlieden, inhoudende Een duidelyke onderwyzinge in de navigatie. . . [bound with] Geographische Tadfel vande Graaden.. Voornaamste Zee-haavens. . .

Rare and important manual originally prepared by Klaas de Vries and improved by Evert Floryn and S.Hollander of the "Schat-Kamer ofte konst der stuurlieden" (Treasure-room of the art of Navigation) parts one and two and published by the widow Gerard Hulst van Keulen in 1802. [bound with] Tafel van de natuurlyke Sinusversus en derzelver logaritmen van Minuut tot Minuut, voor een Quadrant of 90 graden. . . [bound with] Tafel der Logarithmen.

In 1702 appeared with the Amsterdam publisher Johannes Loots a handbook about the art of navigation which proved to be very popular and during the century more than once was issued.
It was the "Schat-Kamer ofte konst der stuurlieden" (Treasure-room of the Art of Navigation) by the Amsterdam teacher in mathematics Klaas de Vries. The book gives a clear picture of several aspects of maritime navigation.
An important issue in the "Treasure-room" is the height measurement of the sun or a star above the horizon, in order to calculate the latitude, as well as how to calculate the meridian.
De Vries mentioned that on board celestial globes were used and he described the three by Dutch sailors most common used instruments for height measurement. He considered the "Graadstok" or "Jacobsstaf" (Cross-staff) as the most important, the other were the "Davis quadrant" and the "spiegelboog" (Mirror-staff). The latter was in 1660 invented by Joost van Breen, a ship provisions-master of the VOC chamber Zeeland.
De Vries described the Cross-staff the most comprehensive and explained how the sailor could make one him selves.

He discussed the "apparent" altitude of a celestial body above the horizon and the necessary corrections to be implemented to calculate the "true" height and he therefore provided the necessary tables.
The "Treasure-room" explained how to calculate the times of high and low water. Knowledge important for departure and arrival at ports.
Navigational guidance, such as meridians, "breedteparallellen", the equator and the tropics, were explained by De Vries. He discussed the compass, compass needles and the variation, application of which was important for safe navigation.

A topic that got special attention was actual position finding on a "platte en de wassende kaart" (Mercator projection chart) done by measuring the distance traveled in nautical miles. The distance was noted in a "handlog" and the speed of the vessel was measured regularly. The log consisted of a buttons labeled long line, rolled on a reel, and at the end a triangular shelf with some lead. One threw the plank at the stern into the sea where it floated and the mate counted with the aid of a hourglass for fifteen seconds, the number of passing nodes. That number corresponded to the speed in miles per hour.
The Treasure-room contained a large number of examples of the various types of calculations and included many sinus, tangent and secant tables by Bernardus Joannes Douwes.
The Treasure-Room contained a large number of 'examples of various types of calculations. These were training issues were the prospective mate could improve skills and test his knowledge.
On ocean routes however the knowledge of sea currents, and prevailing and seasonal winds remained knowledge based on experience of generation to generation which was passed by the sailor.
The "Schat-Kamer" however offered the Dutch sailor the basis of maritime navigation with this edition published exactly one century after its first edition.

Part one pp. 16 -27 we find a listing "Tafel van de watergetven met Nieuwe of Volle Maan". [bound with] Tafelen bevattende De Sinussum, tangenten en Secanten. . .
At the end we find a 41 page listing "Geographische Tafel van de graaden dere breedte en poolshoogte en lengte of middagscirkel, van de Meest Bekende Steeden, rivieren, caapen, Baayen. En inzonderheid der voornaamste Zee-Havens des Aardryks.
Of Korean interest is page 12, with "Corea, op de Zuid-Kust van China. Latitude 34-50 N. Longitude 142-22".

Interesting reading : http://www.knaw.nl/Content/Internet_KNAW/publicaties/pdf/20031017.pdf Fine Sea Chart of Puerto Rico and Hispaniola, published by Johannes Van Keulen II. A rare map since these larger sized sheets were never published in atlases, but were rather used on board of ships at sea for navigating, causing many copies being extensively worn and lost. The chart includes inset maps of Santa Domingo and 3 other enlarged sections of Hispaniola, plus a section that includes I. De Vache. The chart was compiled from the chart made by Amedee Francois Frezier, published by Guilaume Delisle in Paris (1725). Van Keulen has updated Frezier's map with additional hydrographical information provided by Captain Hendrik Lijnslager, a Dutch naval officer. Five inset coastal charts, an inset plan of Santo Domingo City with a numbered key to major sites and monuments, and a superbly decorative dedication cartouche.