Device for use in teaching geometry or trigonometry

Application filed April 17, 1924, Serial No. 707,086.

To all whom it may concern:

Be it known that I, George A. Parkinson, a citizen of the United States, residing· at Madison, in the county of Dane and δ State of Wisconsin, have invented a certain new and useful Improvement in Devices for Use in Teaching Geometry or Trigonometry, of which the following is a specification.

It is frequently the case with the youth10 ful mind that it is lacking in the necessary imaginative power to grasp the significance of mere drawn lines and their proposed superposition upon each other especially, for example, as where equal angles or equal tri15 angles are to be proved such. Minds of this kind can often be helped if such lines, angles &c. be represented in tangible form. Hence it is the object of the present invention to provide an apparatus whereby lines, angles ²⁰ &c. of various sorts are represented in concrete form and the parts of the apparatus manipulated to illustrate many of the elementary geometrical and trigonometrical terms and processes employed in making the ²⁵ proofs necessary in those branches of mathematical science.

The invention is embodied in the example herein shown and described, the features of novelty being finally claimed.

³⁰ In the accompanying drawing—

Figure 1 is a plan view of several parts of my apparatus connected together in a manner adapted to illustrate many of the terms of geometry and trigonometry.

³⁵ ‘ Fig. 2 shows the main frame which is hinged to fold on two axes spread out in edge view.

Fig. 3 shows the same frame folded on one of its axes.

⁴⁰ Fig. 4 illustrates a bar to be applied to the frame and,

Figs. 5, 6 and 7 arcuate pieces of 30, 45, and 60 degrees respectively that may also be applied to the main frame.

⁴⁶ Fig. 8 is a cross section of one of the right angle arms at a slot therein showing a clamping device applied thereto.

Fig. 9 is a detail view of a suspending means for the frame.

⁵⁰ The main frame is composed of four right angled pieces 10 conveniently of equal size and of like shape joined together in the form of a cross by hinges at 11 and 12 so that, for example, the left hand pair can be. ro^ss tated on the hinges 11 to lie on the right hand pair with the angles of the pairs coinciding; or, for example, so that the lower pair can be rotated on the axis of the hinges 12 to lie over the upper pair with the angles of those pairs coinciding. In Fig. 9 is illus- 60 trated a device at 20 whereby the frame may be conveniently hung on a nail on a wall or board. Said device consists of two leaves hinged together, one of said leaves having an eyelet extension, the eye of which, as well 65 as. the axis of the hinge of the leaves referred to,, lies in line with the axis of the hinge at 11. This hanging device can be added if desired, by welding or otherwise securing it to the arms 10 of Fig. 1 and 70 as illustrated in Fig. 9. When spread out flat on a table or hung upon a wall as by means of the hinged eyelet 20 at the vertical axis of the frame it is to be viewed as representing one straight line intersecting an- 75 other at right angles and forming four right angles. In this position also it represents the axis of abscissas and ordinates or the entire angular magnitude about the origin of coordinates. In the construction shown 80 the bar of each of the angle pieces can be formed of sheet metal or other suitable material [—' ]-shape in cross section and provided with a slot 14 so as to receive at its hollow or groove side a square nut 15 provided with a. fixed screw 16 that projects through the slot and receives a milled nut 17 whereby another member such as a rod Fig. 4 or an arc as in Figs. 5, 6 or 7 can be fixed to the angle piece. The square nut δο can be slid along the groove in which it is located and because it fits it is held from turning when the milled nut 17 is turned to clamp the parts together. The rod and the arcs are each shown as provided with a θ⁵series of perforations such as seen at 18 through any of which the screw of the clamping means can be passed to secure it in position. A perforation at 19 near the corners of each of the angle bars permits ¹⁰⁰the attachment of a rod to illustrate angles greater or less than a right angle.

In Fig. 1 is illustrated some of the many ways in which rods and arcs can be applied to the frame and it will be observed by those ¹⁰⁵familiar with mathematics that as shown in this view there are illustrated tangents, a square, several triangles, a trapezium, sectors, sines, cosines, abscissas, ordinates, and other features. In the' practical use of the ¹¹⁰

1,541,179 device, it would not be necessary, or perhaps desirable, to apply at one time as many of the members, as are shown applied in Fig. 1 but only that or those required in a single t> illustration or demonstration. By means of the perforations in the bars their position can be changed or they can be shifted to change the angular magnitudes and the forms of any of the figures to be represented as may be desired or deemed advantageous by the instructor using the apparatus. The clamping of an applied member at one point will usually suffice for practical purposes. If the equality of two angles or triangles or the 1®. similarity of triangles is to be shown by superposition the appropriate rods wil] be connected in symmetrical or similar arrangement to adjoining right angled pieces , and these folded together. If the difference 20 -between two given angles or figures is to he shown this can likewise be .demonstrated by superposition.

The device can be manufactured out of thin strips of sheet metal and more of the 25 parts than shown and in different forms or sizes can be furnished with a set. For example, arcuate pieces cut on dinerent radii can be added.

The forms of the parts can be changed 30 without departing from the gist of the invention as claimed.