A Very Useful Tool

There is a very simple measurement tool that I thought of that can quickly and easily accomplish tasks that are very cumbersome and time-consuming with existing methods. This tool can be very easily homemade and I believe that anyone involved in any kind of building, constructing or, surveying would find it invaluable. I have decided, for various reasons, not to pursue a patent for it any longer. So, I have decided to put it here in the public domain so that anyone can make their own and no one else can get a patent on it.

One day, I drove past some large oil storage tanks in Tonawanda, NY near the South Grand Island Bridges. Just as a mental exercise, I tried to dream up a way to quickly measure the circumference of such tanks or another large, circular object. I started thinking of measuring the curvature over a given linear distance with the idea that the less the curvature per linear distance, the larger the circumference.

But then another idea clicked into my head. What if someone got an ordinary magnetic compass and enlarged either the compass itself or it's mounting so that it was circular and of a known circumference, such as a yard or a meter? Suppose we then placed the edge of the compass against the side of a large oil tank and noted the directional reading given by the compass needle. Then we would note the point on the side of the compass that was in contact with the side of the tank. If we proceeded to rotate the compass over a complete circle and noted the change in the directional reading of the needle, we would have all the information needed to quickly and easily calculate the circumference of the oil tank.

If we placed the compass against the side of the oil tank and noted that the directional reading of the needle was 192 degrees and then rotated the compass a complete circle so that the point on it's edge that had originally contacted the side of the tank was back in the same place, all we would have to do would be to take the fraction of a complete circle that the needle changed during the rotation and multiply it by the circumference of the compass mounting and we would have the answer, the circumference of the tank.

For example, If the compass mounting was one yard in circumference and, upon completion of the rotation the needle had moved from 192 degrees to 196 degrees, the circumference of the tank would be 360/4 times one yard. In other words, 90 yards.

As I stopped to have dinner in a restaurant, my mind really began racing. I realized that I was onto something. I asked the waitress for something I could use for a sheet of paper and by the time I was done, I had filled a side of the paper with all manner of tasks that such a simple device could quickly and easily accomplish. I decided that the device would be called "The Compass Ruler".

I made one of my own by getting a Wal-Mart hiking compass, breaking off the casing and, gluing it onto a piece of plywood I had cut with a jig saw to a circumference of one meter. I knew enough about building and construction to know that such a tool was not in common use. However, I checked extensively to see if such a tool was in use anywhere and found no sign that it was. There was once such a thing as a surveyor's compass, that had fallen into disuse, but it was a compass mounted on a stand and was in no way used like my Compass Ruler would be. On my device, measurements would be taken by actually contacting the side of a structure.

The principle of the operation of the Compass Ruler is simple. Just as a plumb, a weight tied to a string, uses the earth's gravity as a fixed reference point for measurment of vertical angles, the Compass Ruler uses the earth's magnetic field as a fixed reference point for measurement of horizontal angles. The Compass Ruler obviously must be marked around the circumference edge in degrees, just as a protractor would be.

There is an even simpler version of the Compass Ruler. Simply take a square of wood, 1 x 4 for example, and glue a compass in the middle of it. For best results, be sure that it is indeed a square and that each cardinal direction faces toward the middle of one side of the wood. Suppose you have built a corner between two walls or fences and you want to be sure that it does indeed form a right angle. Simply hold one side of your Compass Ruler against one wall and note the directional reading of the needle. Then hold the same side against the other wall. You should get a change in the needle of ninety degrees. Simple.

This method is just as useful if the two walls do not actually contact each other, or for that matter do not even come near each other. This makes the old standby, the builder's square seem awkward and obsolete by comparison. Verifying a right angle by the 3-4-5 Pythagorean Theorem method is also awkward and time-consuming.

Suppose it is necessary to measure the angle beyween any two walls that do not actually intersect. With a builder's square it is impossible. With tape measures it is tedious, time-consuming and, prone to error. With a surveying crew, it is expensive. With my Compass Ruler, it is almost effortless.

What if you have built a long wall or fence and want to verify it's straightness? All you have to do is walk down the wall, taking periodic measurements with the Compass Ruler by placing it's edge against the wall. If the wall is indeed straight, you will get the same directional reading of the needle on every measurement. If it is not straight, by measuring the wall with the Compass Ruler at given intervals, you can tell by how much it curves.

This is also useful for a vast number of other such similar measurements. How would you verify that two parallel walls are truly parallel? Just take a reading on one wall with the Compass Ruler. Then, go to the other wall and put the same edge against that wall. If the walls are parallel, you will get a difference in the directional readings of 180 degrees.

Suppose you wished to set up a series of signs along a road and wished them to all have the same directional orientation. How would you do it? What if you were setting up a sign along the road and wanted it to be set at 45 degrees to the road to give maximum exposure. Or suppose you were building a wall or fence and wished it to run parallel (or perpendicular) to the road.

All of these tasks would be difficult, impossible or expensive with existing methods. With my Compass Ruler, all would be simple and easy. To measure the directional orientation of the road with the Compass Ruler, simply place the device on the road surface alongside a traffic line on the road.

Measurement of curvature is just as easy with the Compass Ruler. Just take readings against the curved structure at regular intervals. Curvature can be expressed as change in the directional orientation of the needle per given linear distance. Another advantage of either version of the Compass Ruler, either the circular or the simpler square version of the device, is that contact measurements, such as those described above, are not hampered if two structures to be measured and compared are not visible from each other or if there is an obstacle, like a row of bushes, between two structures.

Surveying is easy with the Compass Ruler. Suppose you want to get an accurate measurement of the distance to a certain remote point. First, you would either set up or pick out a remote visible reference point to use in the measurements. Then you would mark the local point from which you would take the measurement to the remote point. Then you would establish a measurement point a convenient distance away so that a line from the local point (Point A) to the measurement point (Point B) would form a right angle with a line from point A to the remote point (Point C).

Using a straight-edge, such as a perfectly straight 1 x 4 board, you would sight on the remote point C from the local point A looking straight down the straight-edge. You would use the Compass Ruler to note the directional orientation of the straight-edge as it points from Point A to Point C. You would then go to the measurement Point B that you have selected and take another sighting on the remote Point C from there.

All you would than have to do is take the difference in the angular reading of the two measurements. Using a scientific calculator, you would get the cotangent of the angular difference. You would then multiply the cotangent by the distance from Point A, the local point, to the measurement Point B. That would give you the distance from Point A to the remote Point C.

Obviously, for best results in surveying using the Compass Ruler, measurements must be taken carefully. The distance from Point A to Point B must be accurately measured. And, the same spot on the remote point must be sighted upon. The longer the carefully measured distance from Point A to Point B is in relation to the distance from Point A to the remote Point C is, the better the result will be. It should always be at least 10% of the distance.

It is not necessary to have a right angle between the two lines from points A to C and from A to B, but if not, the simplicity of a cotangent calculation will be lost and a graphical calculation will become necessary. If possible, the baseline for the measurement from Point A to Point B can make use of a pre-existant line, such as a road.

The straight-edge can be built onto the Compass Ruler if it is to be used for surveying. For even better results, the straight-edge can be fitted with a small telescope, a laser pointer, or, both. A vertically diagonal mirror can make it possible to see the compass on the Compass Ruler at the same time that the sighting is being done. For a finishing touch, the entire device can be set on a mounting.

To set up a marker, such as a traffic cone, at a given distance in a given direction from a starting point, use the reverse of this method. Pre-set a sighting from a Point B to that distance and have a rodman walk with the marker until he is in the sight. Then use hand signals or radio/phone communication to have the marker set up at the correct point.

Suppose you are out on the water in a boat and wish to measure how far you are from shore because you notice a shipwreck or some other object of interest under the water and wish to record the position. You would pick out two easily recognizable objects on shore such as trees or large rocks. The two objects should be in a line perpendicular to the line between you and one of the objects. Measure the angle between the two objects from where you are in the boat and record it.

Later, you would carefully measure the distance between the two objects using a tape measure or a map. Then you would take the cotangent of the angle measured from the boat and multiply it by that distance. Alternatively, you could simply take the directional readings of any two (or more) prominently visible, fixed position objects. The position on the water could then be charted using a map or satellite photo of the area.

Astronomers have long used this technique to measure the distance to stars, it is known as parallax. The carefully measured distance from Point A to Point B is referred to as the baseline. The same principle can be used with the Compass Ruler to map an entire area. Simply pick out visible objects such as trees, houses, etc. Measure the distances from a central point to the objects and then measure the angular distances between those objects from the central point. The map then can be easily made using a ruler and protractor. Of course, on complex maps, more than one central point can be used. If the terrain to be mapped is hilly, the logical place for the central points would obviously be on the high ground.

Aside from the contact measurement and surveying versions, there is yet version of the Compass Ruler, the drawing version. Simply fasten or glue a small compass to a straight-edge such as a ruler and it makes the protractor used in geometric drawings just as obsolete as the builder's square is in construction. To draw two lines at a certain angle to each other, simply draw one, noting the angle indicated on the compass dial. Then move the straight-edge so that the difference showing on the dial is now the desired angle and then draw the second line. To measure the angle between two existing lines, simply reverse this process.

If the drawing paper is securely taped down, aligned either east-west or north-south with the compass for best results, an entire geometric drawing can be made with unprecedented accuracy using the drawing version of the Compass Ruler. Parallel lines will have the same compass dial reading anywhere in the drawing. Perpendicular lines will differ 90 degrees in reading. Existing methods are far inferior to this. Of course, it would be simple to draw a map that was surveyed using the surveying version of the tool, just drawing the measurements on paper.

There are certainly many more everyday applications of this simple but extremely useful device. The device could also bring geometry and trigonometry classes to life. The lessons that now consist of drawing lines and circles on paper could occasionally be done as actual measurements in the gym or schoolyard.

Anyone can make their own of any version of the Compass Ruler, the circular or the simpler square version for contact measurements. Or the surveying or drawing versions with an attached or accompanying straight-edge. It can also be manufactured and sold although it will not be patentable now that I have put it in the public domain.

I will not earn any money on this but I just want to have contributed something to the world. We read of George Washington Carver and how he revealed many things that the humble peanut can be used for. I would like to do the same thing for the simple device known as the compass. Just as GPS systems are becoming ubiquitous and it seems to be of little use any more, we see that there is a whole world of tasks that it can accomplish most effectively. Any simple compass would have it's usefulness multiplied if it were encased with a straight side to perform some of the measurements listed above.