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Map Making- Collaborative Data Collection

Exciting opportunities exist for schools within a region to work together on map making projects. These projects would be an excellent exercise in English as well as mathematics.... YOU try describing clearly, unambiguously, things that you can only see in (your) far distance!

I live on the south coast of England. There is a line of hills along that coast. About 20 miles to the north, there is another line of hills. If I make some bearing readings between places I can get to easily, and a collaborating school on the northern hills does the same, then we can make a bigger map that either of us could have made on our own in the same time. Locations separated by big (but not too big!) bodies of water have similar opportunities.... and society has kindly provided lighthouses which are very helpful for such exercises!

Guidelines for data collection format:

Any set of data should have a preface indicating the level of sophistication of the equipment and surveyors. Some map making participants will enjoy using figures provided by a helpful parent who happens to have a $5,000 theolodite capable of superior readings. Others will want to restrict themselves to a 'do- it- ourselves' approach. The preface should indicate a person to contact over questions. The age of the surveyors may be of interest.

The units used for the readings should be clearly stated. The easiest way to do this is to say how many of your units make a complete circle, e.g. if you are measuring in degrees: 360. If you are using fractions, are they decimal, e.g. 30.5 meaning 30 and one half, or are you using degrees, minutes, seconds? (I would 'vote' for decimal fractions!)

Within each set of data, there will be pages for bearings taken from a specific location, i.e. a point on the map. For a specific location, there may be multiple pages. This could arise from having a number of surveyors take reading from that location, or visits on different days. (However, in general, if you can be bothered, I think a 'consolidated' page for each location would probably be worthwhile, unless you feel it dilutes the realism of the exercise too much.)

Each page of data from a location should be dated. It should have a clear description of where the location is. Remember that the most useful locations are those which can be seen from other locations, so describe the location in terms of what it would look like from afar. If the units of your measurements are not the same for all of you sheets, make a note of what they are. (See above.) The sheet should say who is responsible for the data on it.

The sheet will then have a minimum of three columns. Please group them together, in this order, so that your sheets can be used easily by others. By all means add columns before or after these:

First column: ID of point to which bearing is being taken: three digits (See more, later)

Second column: Size of angle between this point and reference point. (See more later.)

Third column: Description of point to which bearing is being taken. E.g. 'White lighthouse by red cliffs.' Some indication of distance is helpful here, too. Often comparing the it to the distance to a known point is the easiest solution, e.g. 'about half as far away as the cathedral spire.' Ideally, your map making won't rely on the maps others have made before you... that would be a little tautological, wouldn't it? But it is silly to be too much of a purist! Note that you don't have to do a perfect description of the location. You only need something good enough to distinguish this steeple, lighthouse, radio mast, chimney, etc from any similar objects in the same vicinity.

Going back to cover some details:

First column: Initially, I tried to be organized about my location id system. The difficulties of accessing my total location id database while working in the field became too tedious. Now, I just assign three digit ids to things, and combine those with the sheet's date and it's location, e.g. 'location 234 of the readings taken from the lighthouse in Shoreham on 12 December 1999.' For collaborative efforts, it will be simple enough to add 'by contributor xxx' to that to keep all of the 'location 234's distinguished.

By the way: I find that by far the best way to approach the job once I'm at a site is to complete my list of points I'm going to take readings to first, and then work down it taking the bearings. It helps to do them in order, e.g. left to right.

Concerning the second column:
Important: My theolodite is only able to scan a 180 degree arc. I choose a significant tem at one end of a 180 degree arc and use that as a reference point. Lets say that my theolodite reads 10 degrees when pointed to it. I then read the numbers off my theolodite for other locations. Let's say that location 235 comes in at 30, location 236 comes in at 45 and location 237 comes in at 170. From time to time, and certainly at the end of a set, I check back to the first location. If the theolodite doesn't still read 10, I'm in trouble. (The device has moved during the readings, and they must be thrown out.) From the example given, the angle between 235 and 236 is 15 degrees, etc. Now the important bit: If I want to take further readings, when I reposition my theolodite, I need to include location 237 in the new view. If, now, the theolodite reads 35 degrees, and my reading for the next location (238) is 55 degrees, I can work out that between, say, 236 and 238, the angle is 45 degrees. Be sure to mark clearly on the data collection sheet any time the theolodite is rotated, so that data users know when to re-base their calculations. Note that when you are out collecting data, you don't need to know where 'north', or somesuch is.

If you are lucky enough to live in an area which particularly lends itself to mapping by bearings, perhaps you would work up data to share with others? In pre-map making days, I once stood on a hillside with roughly 1200 square miles visible to me. Now THAT was a map making opportunity! I would be glad to 'warehouse' such data, or publish your eddress so that others could obtain it from you directly.

On a more personal level, I am always looking for access to good places to take bearings from anywhere in the souther half of England. If you have 'a room with a view', or control of access to a high place, I'd welcome the chance to visit.

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