Printable safey compass!!!?

Question

I hve an Earth Science Lab which is due on Monday and I can't figure out how to use my geographic safety compass, however I did fine with the ones in class. Is there a difference between Geometric and Geological Safety compasses? I need one which will help me draw the circles for the seismograms that will help me locate the epicenter. I'm only in middle school, so please help!!!

The one i'm looking for has a circle in the middle which you line up with the distance to the epicenter and then you put one of the small wholes further down on the tool and then you put your pencil through the small whole. Then you line up the original hole you had on the number of distance and you put it on the name of the city in which you are doing the seismograph for, and then draw a circle.

Answer 1

No, I don't think there is any difference.

I'm confused by your question because a safety compass is usually a mechanical device that has a pencil on one side and a pointer on the other side, and is a "V" shaped, adjustable pair of arms.
Here is a picture of a simple one:
http://www.teachersparadise.com/c/product_info.php/products_id/56752

To use one of the these you simply put the pointed end on the center of the circle you want to draw, and rotate the other arm that holds the pencil in a circle around that center point.

A more sophisticated version is often used by draftsmen, and a similar device is called a divider, which doesn't have the pencil on one side so it can only be used for measuring.
See these examples:
http://www.draftingsteals.com/catalog-drafting---drawing-aides-compass---dividers.html

If you did it in class, you should be able to understand the concept. It is even possible to make a substitute for a compass with only a piece of string and a thumbtack. If you put the thumbtack through your string on the center point, you can rotate the string with a pencil attached and make a regular circle.

The problem you are trying to solve involves finding where two or more circles intersect. The radius of the circle probably represents the travel time, or the amount of time between when the earthquake occurred and when it reached a seismic station. Here is a web site that illustrates what I am trying to describe (scroll down about halfway down the page):
http://servercc.oakton.edu/~billtong/eas100lab/lab10quake.htm

Hope this helps.

Answer 2

Any compass that draws decent circles will be fine for this exercise.