Nocturnal, George Waymouth

After returning from an unsuccessful exploration trip to Labrador, in 1602 George Waymouth set down to write and illustrate his book The Jewell of Artes. Two copies were apparently presented to the new king, James I, in 1604, possibly as part of a search for employment. Two manuscripts exist, one at the Beineke Library at Yale University, the other in the British Library. James Baxter, founder of the Maine Historical Society, had a copy of the British Library volume made, which was on display at the Tercentenary of Waymouth’s voyage but since has disappeared.

The Method of Using an Astrolabe

This classic image of using an astrolabe on shore comes from Medina's "Arte de Navegar," 1545.

The navigator is letting the sun shine through the top hole on the sight onto the bottom hole.

Astrolabe Diagram

Drawing of an astrolabe from Medina's Arte de Navegar, 1545. The seaman's astrolabe was a graduated ring or disc fitted with a sighting rule pivoted at the center. The instrument was suspended so that it hung vertically. The user then turned the sighting rule so that the sun or star could be sighted along it and the altitude read off the ring. It dates back to ancient Greece and was heavily used in the Islamic world. The first records of a seagoing version date to around 1481.

A Chip Log, a Log Line Reel, and a Sand Glass

The chip log, a log line reel, and the sand glass used for measuring the speed of a vessel through the water. The chip is tossed, the sand glass turned, the line let out, and the number of knots in the line are counted until the sand glass empties. The number of knots that have passed is the speed of the vessel in knots or nautical miles per hour.

This illustration is from Bowditch's New American Practical Navigator,1868, Plate VI.

Points of the Compass

Sixteenth-century rendition of a compass rose, with 32 points.

North by East
North North East
Northeast by North
Northeast by East
East North East
East by North

is the system which repeats in each quarter. The points are 11 1/4 degrees apart: the result of dividing 360 degrees by 8 which is what happens when a circle is quartered 4 times.

Portrait of Copernicus

This portrait of Copernicus comes from the Nicolaus Copernicus Museum in Frombork, Poland. Copernicus showed that the earth was not the center of the universe, but that the sun was the center of a solar system.

The Celestial Sphere

This diagram shows the earth inside an imaginary celestial sphere, along with the names of coordinate systems: declination and right ascension. This also shows the Sidereal Hour Angle, which is 360 degrees minus the Right Ascension.

The drawing is from Bowditch's American Practical Navigator, H.O. Pub. No. 9, 1962, p. 382.

Modern Compass Rose

This compass rose, appearing on a 1993 chart, Penobscot River, NOAA Number 13309 , gives directions in degrees, but points are still included. It has three concentric roses, one for true directions and two for magnetic directions with the inner one graduated in points of 11 1/4 degrees. The inner roses have been set to the local magnetic variation of 18 degrees west.

Meridians of Longitude

Illustration showing how longitude lines cut the globe in planes that intersect at the polar axis. Longitude is a measurement that identifies a location as being a certain distance east or west of a prime meridian. Penobscot Marine Museum is located 68 degrees 55 minutes west of the Prime Meridian which passes through Greenwich, England.

This illustration is from Bowditch's American Practical Navigator, H.O. Pub. No. 9, 1975, p. 444.

Parallels of Latitude

Illustration showing how latitude lines cut the globe in parallel planes, with the longest latitude line being the equator. Latitude is a measurement that identifies a location as being so far north or south of the equator. Penobscot Marine Museum is located 44 degrees 27 minutes north of the equator.

This illustration is from Bowditch's American Practical Navigator, H.O. Pub. No. 9, 1975, p. 445.


Subscribe to RSS - Photo/Image