Technical Field:

Geometrical Application ( Geometric Instrument ) Background Art:

The compass is an old invention to draw a circle , it consists of two sticks one of them has pencil and the other has a metallic pin , the two sticks are contacted above by bolt , and we turn the compass to draw a circle as in the figure (1).

The problem of the last art: - The metallic pin is very danger especially when the kids play together, however it makes infections by some viruses as virus "C", and another diseases could by infect the body by blood if someone is infected and the other is good. - The difficulty of drawing circles, the kids find it is difficult when they cannot control with the compass to draw perfect circle as they want. - The bolt in the compass is a weak point because we want to check its power by screwdriver every time. - The point of contacting with the pencil is another weak point because we cannot fix the pencil perfectly sometimes when we draw the circle. - To draw a circle with radius of length x we must measure the length of distance between the pin and the pencil on ruler and that is difficult to some pupils to do sometimes.

Disclosure of Invention

The new compass has not these weak points , it has not the metallic pin could infect the kids , but it contains a circular disc has a hole in the center ( central hole) , we can put the pencil in it to determine the center of circle , it is free to turn the disc about this hole , in the disc there is another hole ( side hole) to put another pencil which will draw the circle, we can move the side hole inside or outside to the center to change the length of radius of circle, in the disc there is a pointer to measure the length of radius as in the figure (2) , the metal slices are not sliding easily (but hardly) to make the length of radius not changes easily , we can keep this hard moving by make a very small metallic part on the side of the slices makes the moving hardly when we draw the circle as in the figure (3)when the slices moves outside the centimeters on them measure the length of radius in the pointer , we can see that from hole in the disc shows the centimeters on the slide slices as in the figure (2) , we can make three or four slices , whatever the number of slices increase , then the length of radius we can use increase. The inventor see the best number of slices is 4 slices and the best length of slice is 4 centimeters , then we can open the compass to draw a circle of 16 centimeters as the greatest circle we can draw.

The complete Description

The new compass consists of central hole rounded by transparent plastic circular disc available to make rotation easily around this central hole and there is another hole at the side (side hole) connected to metal slides available to slide one on the other internally or externally from the circular disc and recorded on it centimeters scale- figure (2)- when we pull the side hole externally the slices slide one on the other figure (3)- the centimeters moves on the pointer until to get the length of radius we want to draw the circle - the first slice moves externally of length 4 centimeters as example and when it became outside it pulls the second slice , when the second slice became outside the length of radius will be 8 cm ,then the second slice start to pull the third slice and so on , we can stop the pulling of slices when we reach to the length of radius we want , when we push the slices internally by pressing on them as the aerial of radio , the length of radius will be decrease as shown as on the pointer, we put the pencil in the central hole to draw the center of circle and for fixing the compass , then we put another pencil in the side hole after determent the radius length to draw the circle by the rotation of the pencil in the side hole about the pencil in the central hole until we draw the complete circle figure (4). The method of working

To use the new compass in the circles drawing we pull the side hole externally and internally until we get the wanted radius length , then we put the compass on the paper , we put a pencil in the central hole in the center of disc to draw the center of circle, we put another pencil in the side hole, with rotation of the second pencil to the first one we can draw the circle we want figure (4).

Brief Description of the Drawings:-

The figure number (1) shows the old compass which consists of (1) The first stick. (2) The second stick. (3) The metallic pin. (4) The pencil. (5) The bolt.

The figure number (2) shows the new compass which consists of (1) A disc available to be turned easily about central hole. (2) The central hole. (3) The side hole which could be moved internally or externally to determine the length of radius. (4) The metallic slices which slid one on the other - there are centimeters on them. (5) The pointer has the black arrow points to the centimeter of the radius of the circle.

The figure number (3) shows how the metallic slices can slide one on the other (1) The external slice has in its end the side hole - when we pull it , it will pull in the second end the second slice. (2) The second slice - when we pull the second slice externally it will pull the third slice from its end like the aerial of radio (3) A small part of metal to make the sliding not easy and to make the slide pull the other.(4)The hole in which the small metallic part will be put in.

The figure number (4) shows the method of using of the new compass to draw a circle (1) The pencil which will be used to draw the center of circle. (2) The second pencil which will be used for drawing the circle. (3) The pointer. (4) The circle. (5) The circular disc. (6) The metallic slices which slide one on the other internally or externally to increase or decrease the length of radius.