Ptolemy’s Grid System the Most Important Discovery to Navigation

 “Ptolemy’s Grid System the Most Important Discovery to Navigation”  

 Name: Taylor Bishop

 Instructor: Michael Lyle  

 Date: September 10, 2016  

 Course: Oceanography Lecture (111)

                      “Ptolemy’s Grid System the Most Important Discovery to Navigation”  

The episode of James Burke’s Point of View explained the many moments on how people throughout history came up with ideas to help the future of finding location. In the episode Point of View, Mr. Burke gives people a real understanding of how the universe was looked at in early times. He reiterates the importance of these opportunities to help people visualize and appreciate how the people back then set the tone for how we can read maps or locate where we are today. This synopsis explains one of the “aha moments” that Mr. Burke explained to be crucial, and this happened to be the importance of the grid system on maps. Throughout the episode, Mr. Burke points out how this discovery has been used all through history, how the grid system is still used today to help humanity find or locate where they are going, and not to mention their exact location on the map. In this paper, the reader will see who found the discovery, what the problems were before the discovery, and how this development has helped humanity in current time.

           Unfortunately, in the early world navigators had many problems, and the biggest problem the explorers had was being able to locate where they were while taking their voyage. During the Greek era, geographers started to measure the circumference of the earth, and this was a large swing of success in cartographic science (Briney 2016). After geographers found ways of finding the earth circumference, a gentleman named Claudius Ptolemy, discovered a new system of mapping called longitude and latitude (Sobel 1995). Anyone that was studying these methods was following the way of Ptolemy’s grid system, and this was the new evolution of cartography.

 At the beginning of map making, there were some problems, it was small-scale, and had a flat representation with a small proportion of the earth’s surface (Briney, 2016). For many centuries there were arguments after an argument on the shape of the earth. Claudius Ptolemy was the first man that changed these problems even though his calculations were not used in his time (Sobel 1995). Ptolemy wanted anyone who was reading his calculations to know that the earth was a sphere, each locality on the surface admits a tangent plane, this was called the horizon plane (Berggren, 2000). He also came up with an idea for any explorer to use longitude and latitude, so they knew what stars were able to be seen while being on a voyage. Another thing he wanted the observer to know while viewing his map while observing around the north or south pole, while their latitude being 90 degrees, the explorer would find that the equator lines up with the horizon and any stars north which are visible at night (Berggren, 2000).

 When Ptolemy came up with this grid system, he made the grid system on earth, to be related to the grid system in the sky, which helped measure latitude in the northern hemisphere. Not to mention the coordinates that Ptolemy came up with were given to 8,000 places or locations. (Berggren, 2000). He also measured latitude based on the length of the longest day of the year, and longitude is determined on a base of time. The measurement of longitude was 15 degrees equal to one hour.  In today's world, this is our globe as we know it, with 90 degrees from the equator to each pole, which indicates that latitude is north and south of the equator. One of the major issues in those times was measuring distances, and figuring out how to measure longitude (Briney 2016). The reason being was that cartographers didn’t know the exact times in the different parts of the world, so the measurement of longitude was tough to measure. Ptolemy then came up with the idea that the only way to measure longitude in the old world was from an astronomical view and observing the sky (Berggren, 2000).

[pic 1]

Figure 1: Ptolemy’s modified spherical project of the world on a map using parallels and meridians, while giving a likeness to earth’s surface on a sheet of paper (Berggren, 2000)

        Ptolemy invented the grid system for maps, he came up with two ways of illustrating a grid of lines on a flat map. However, this is how he represented his circles of longitude and latitude on a globe (Marx, 2011). Even though this was new to the cartographic world, his grid gave an illustration of a spherical earth surface, to an extent, and this preserved the proportionality of distances. The hardest thing Ptolemy had to do with this new grid system was using circular arcs to represent parallels and meridians.  There were many issues with the location in the early times, and Ptolemy’s work wasn’t appreciated until the 1400’s (Sobel 1995).