How to Read Maps Using Explorers Routes

A Student'southward Guide to Mapmaking
- by Ralph Ehrenberg

What Is a Map?

Maps are one of the well-nigh important types of documents associated with exploration. A map is a graphic representation that facilitates a spatial understanding of things, concepts, conditions, processes or events in the human world. They are used past explorers to help notice their way. They are likewise prepared past explorers to certificate or record what in fact they discovered.

There are many types of maps, each determined by the purpose for which it is designed. The road maps that your parents use are way-finding or route maps that guide them from ane place to some other. The daily atmospheric condition charts that you see on goggle box are special-purpose maps of natural phenomena that help people plan whether or not they will travel to a particular place! The geographical maps in your textbooks show the distribution of diverse things or processes over big areas. What types of maps practice you think explorers used and prepared?

Step i: Where Are We?

The start step an explorer takes in preparing a map is to determine his or her location. The location of any betoken or place on the earth's surface can be understood simply with reference to its distance and management from some other point or place. The easiest way to practise this is to utilize familiar landmarks.

Your bus driver uses landmarks everyday as he or she drives you safely to school. You may observe these landmarks or guide points likewise. They may exist in the form of man-fabricated objects representing the human or cultural landscape such as theaters, churches, and synagogues. They may exist topographic or physical landforms such as rivers and hills. Or they may be prominent plants such as large trees and distinctive shrubs. Such landmarks provide a relative location or mental frame of reference, and are useful for guiding people over small areas.

Explorers and mapmakers, however, must decide the verbal location of a place or point on the earth'south surface so that whoever uses their maps can easily find whatever site depicted without depending upon another person for guidance.

This is washed past dividing the earth's surface into a grid system of imaginary lines similar to the manner a football field is marked off to assistance officials and spectators locate the placement of the football game with precision and accurateness. When applied to the globe'southward surface, these lines are designated parallels of latitude and meridians of longitude.

Breadth establishes position north or southward of the equator while longitude determines position e or west of a prime number height, the cipher point from which longitude is measured. This is called the geographic coordinate system of parallels and meridians, and provides a scientific frame of reference for locating any place on the earth'southward surface. More data on latitude, longitude and prime tiptop can be found at the following Web pages:

- Comptons Encylopedia; Longitude and Latitude

- Hammond Wac; Longitude and Latitude

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Step 2: Determining Projection and Calibration

The transfer of this imaginary grid system of parallels and meridians of the Globe ( a sphere) to a pocket-size, apartment map, nevertheless, cannot be done without distorting in some way the map'south shape, expanse, distance or direction and irresolute its scale. These distortions can exist easily observed by drawing a grid system of parallel lines on a large grapefruit and then laying the peeling flat.

To compensate for these distortions, mapmakers construct map projections to emphasize or de-emphasize one or more of the basic map properties cited. Follow this link to view different map projections and their properties:

- Map Projections

Map scale refers to the proportional human relationship betwixt the distance of two points on a map with the actual distance on the ground. Map calibration tin can be expressed in words ("one inch equals one mile"), graphically (with a bar divided into sections), or as a representative fraction (1:24,000 or 1/24,000). The larger the map calibration, the smaller the expanse shown. The following Web page illustrates map calibration:

- Map Calibration

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Step three: Adding Symbols

Once the map's projection and scale are determined, the side by side step undertaken by an explorer is to add features of the physical, natural, and cultural landscapes that will most accurately and vividly represent the pattern and texture of the expanse mapped. This is washed by simplifying (generalizing) the features to be shown by using symbols.

Map symbols are minor graphic images that stand for something else. They may be depicted by pictorial images, abstract combinations of points and lines, or tonal shading and color tints. For example, an explorer might show an Indian hamlet by using a miniature picture of a teepee.

The mapmaker oftentimes uses a key or legend to point what symbol matches what feature. For examples of map symbols used in orienteering, visit this Web page:

- Map Symbols

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Stride four: Naming Things

The final footstep in the grooming of an explorer's map is selecting and applying geographical names that identify relevant features, landmarks, and places.

Geographical names are fundamental elements of maps. They also provide important reference frameworks in our daily life.

During the early history of America, explorers and mapmakers named many of our mountains, rivers, and towns. Today, these names form part of our cultural heritage and provide clues to the history of our country'south settlement and people. A list of almost two one thousand thousand physical and cultural geographical features in the The states is available through the following link:

- Geographical Features

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Mapmaking in the Time of Lewis and Clark

Ii hundred years ago when Lewis and Clark gear up out to explore the Far West, the basic principles and techniques of scientific mapmaking were well established. As early on as the 2nd century A. D. the Greek geographer Claudius Ptolemy prepared instructions for the structure of maps using latitude and longitude as a geographical frame of reference. During the great historic period of European seagoing exploration, Portuguese, Castilian, Italian, Dutch and English navigators developed and improved a variety of instruments to mensurate one's position on the Earth's surface.

Compass Route Mapping

Past 1800 overland explorers relied primarily upon compass route mapping to prepare their maps. This is likewise called "dead reckoning." In compass route mapping or "dead reckoning," mapping is based upon determining direction and distance along the line of exploration. The direction or grade of the route is determined by magnetic compass, an aboriginal instrument invented in China and used in Europe since at least the eleventh century.

Past the beginning of the nineteenth century, mapmakers were aware that their compasses pointed to the magnetic northward pole rather than the geographic n pole, and that they had to brand corrections for this variation. Several magnetic variation maps of North America had been published past 1804 to help surveyors brand these corrections but none existed for the Far West.

Distance was adamant by a variety of methods. These included devices that measured the speed of travel:
In rivers or streams they used log-lines or counted paddle-strokes.
On state they counted their steps (pacing), and later, used viameters (odometers) attached to a bike.
For more accurate measurements, some explorers as well carried a one-hundred link chain called a Gunter's chain. This chain measured precisely 66 feet in length.
The summit of the mountains and hills along the route were oft measured as well, using an musical instrument called a barometer.

Angelic Navigation

Nineteenth century explorers checked the accuracy of their compass bearings by angelic observation. This is chosen celestial navigation.

In the Northern Hemisphere, breadth was determined by measuring the distance or bending of the North Star, Polaris, from the horizon, with finely scaled brass instruments chosen octants or sextants. Determining the distance of Polaris on state required another instrument called an artificial horizon since the true horizon is generally obscured.

Longitude was more difficult to determine during a cross-country expedition. The most accurate method is to compare the time of a portable clock or chronometer set up according to a prime superlative with local time determined by celestial ascertainment. The results were then calculated by reference to astronomical tables of transits (ephemeris) by experts known every bit computers. Unfortunately, the marine chronometers of the period were too bulky and sensitive to carry overland and pocket chronometers were often likewise frail to survive long distances.

Local time in North America was determined past measuring lunar distances (the distances betwixt the moon and sure stars) and calculated according to Nautical Almanac and Nautical Ephemeris, kickoff published in England in 1765.

Map Publishing in 1800

Upon completion of an exploring trek, the field maps would be redrawn on one sheet at a smaller calibration then turned over to an engraver for publishing.

Today, we are surrounded by maps. We meet them daily on tv, in our newspapers, in our books, and on our computer screens.

But in 1800, maps were rare, expensive, and available only to the leaders of guild. They as well looked different than the maps we use today. In 1800 maps were printed from either wood blocks or engraved copperplates and they were hand colored. These were time-consuming processes that required skilled craftsmen and artists. For an illustrated clarification of woodcut and copperplate engraving, see the post-obit link:

- Woodcut and copperplate engraving

The detail shown on a map was also more limited in 1800 than today. Large areas of maps were often left blank for lack of information, or they were filled in with decorative lettering or fanciful pictures. If terrain features such as hills and mountains were depicted, they were generally shown in the form of "hairy caterpillars" or uncomplicated drawings of hill forms. These techniques were well adapted to both woodcut and copper engraving.

Maps as well reflected the lack of accurate, detailed field surveys available to mapmakers. Since no standards existed to guide mapmakers, symbols and lettering varied greatly from map to map.

The selection of the prime superlative also varied from place to identify earlier the adoption of Greenwich, England in 1874. Ofttimes it was measured from the nation's capital or from the city in which the map was published. In the United States, map publishers oft used Washington, D.C., as the prime meridian during the starting time one-half of the nineteenth century.

Most of the maps available in the U.s. at this time were published in England or France. Because the United States had few trained mapmakers in 1800, many of the first American cartographers were recruited from Europe or were former armed services officers.

One of America'southward foremost mapmakers was our first president, George Washington. He mapped large areas of the frontier as a immature land surveyor. Another was our third president, Thomas Jefferson, whose begetter was also a land surveyor and mapmaker. The maps prepared by Washington and Jefferson provide adept examples of the state of mapmaking at the shut of the eighteenth century. These maps can be constitute on the following pages:

Washington and Jefferson page1

Washington and Jefferson page2

George Washington map