GB2122348A - Teaching aid - Google Patents

Abstract

A device for use in demonstrating horizontal, vertical, angles of inclination and in general the principles of surveying comprises a circular hollow tube 1 which is half filled with a liquid 2 and mounted in a central aperture3 in a parallelepipedic block 4, with two parallel faces 7,8 of the block parallel to the plane if the tube 1. An angular scale 14 is associated with and centred on the axis of the circle of the tube and a sighting means 15 is angularly movable over the scale and has an edge 16 extending across a diameter of the scale and alignable with the free surfaces of the liquid in the tube 1.The sighting means is guided in its angular movement by lugs 21 engaging a ring 12 on which the scale is mounted and has outturned ends 18,19 for use in sighting a distant object. <IMAGE>

Description

SPECIFICATION Devices primarily for use as teaching aids The present invention relates to a device which is primarily for use as a teaching aid to demonstrate horizontal, vertical, angles of inclination, and in general the principles of surveying.

According to one aspect of the present invention there is provided a device comprising a hollow circular tube which is half filled with liquid, an angular scale associated with the tube and centred on the centre of the circle of the tube, and sighting means angularly moveable over the scale.

Advantageously the tube is mounted in a block which is provided with mutually perpendicular faces, parallel pairs of which extend parallel and perpendiocular to the plane of the tube. The block may be provided with a circular central aperture in which the tube is located and the sighting device may be mounted on the block. The scale may be mounted on a ring which engages in the central aperture in the block and serves to retain the tube in the block and the sighting means may be provided with lugs engaging the inner surface of the ring to guide the device in rotation.

The sighting device preferably has a linear edge which extends along a diameter of the scale and of the tube and is alignable with the free surfaces of the liquid in the tube. Advantageously the sighting means is in the form of bar, one edge of which extends along a diameter of the scale and which has outturned ends which can be used for sighting a distant object.

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a perspective view of an embodiment of a device according to the present invention; Figure 2 is an exploded sectional view showing the block and ring on which the scale is mounted of the device of Figure 1; Figure 3 is a front elevation of another embodiment of device according to the present invention; and Figure 4 is a section on the line IV-IV of Figure 3.

The device shown in Figures 1 and 2 comprises a circular hollow tube 1, for example of pyrex (RTM), which is filled with a liquid 2 which is preferably coloured so as to make it visible, such for example as water with Gentian Violet added, the remainder of the tube being evacuated of air.

The tube 1 is mounted in a central aperture 3 in a mounting block 4, for example of polyurethane foam, which is parallelepipedic and has mutually perpendicular pairs of parallel side faces 5,6 extending perpendicular to the plane of the tube 1 and front and back faces 7,8 between which the aperture 3 extends, extending parallel to the plane of the tube.

The aperture 3 in the block 4 is, as shown in Figure 2, stepped and is provided with an arcuate step 9 intermediate linear steps 10, 11 and in which the tube is received. The tube is retained in place by an annular member or ring 12 which is received instep 11 and is provided with a part arcuate profile 13 for laterally engaging the tube. The ring 12 is adhered or otherwise fixed in the block 4.

An angular scale 14 is provided on the outer face of the ring 12, the scale being centred on the centre of the circle of the tube 1.

Sighting means 15 is associated with the tube 1 and scale 14 and comprises a bar 15 which is angularly moveable about the axis of the circle of the tube 1. The bar 15 has linear edges 16, 17 of which one edge 16 is aligned with a diameter of the scale 14 and tube 1 so that the edge can be aligned with the free end surfaces of the liquid in the tube 1, and has outturned ends having coplanar edges 18, 19 which can be used for sighting distant objects, edge 18 being cut away at 20 for convenience of sighting.

As shown in Figures 1 and 2, the bar 15 is guided in its angular movement by lugs 21 which engage the inner surface of the ring at diametrically opposite points. The bar 15 can be fixed in any required position by clamping bars 22 behind which the bar 15 extends and which are mounted on the front face 7 of the block to either side of the aperture 3. The bars 22 can be clamped against the block to hold the sighting bar 15 in any required position by threaded clamping bolts 23.

As shown, two of the perpendicular side faces 5,6 of the block are provided with V-shaped grooves 24 and the front face 7 is provided with perpendicularly arranged conventional spirit-levels for checking the orientation of the front face.

The embodiment shown in Figures 3 and 4 differs from that shown in Figures 1 and 2 in the way the sighting bar 1 spa is mounted on the block 4. In this embodiment the same reference numerals have been used for like parts. As shown, the back face 8 of the block 4 is provided with recesses 30 in which the ends of a backing strip 31 are received. The strip 31 extends diametrically of the tube 1 (not shown) and is provided with an opening 32 centred on the axis of the tube 1 in which a locking or clamping screw 33 is received, the screw being threaded into the sighting bar 15a. As in the previous embodiment, the sighting bar 1 5a is provided with lugs 21a which engage the inner surface of the ring 12.However, in this embodiment the lugs obscure immediate visibility of the tube 1 and accordingly the edge 16 of the bar 1 5a is cut away at 34 to reveal the portions of the tube which are level with the edge 16 of the sighting bar.

This shaping of the edge 16 of the barfascilitates alignment of the edge 16 of the bar with the free surfaces of the liquid in the tube 1.

In this embodiment, the sighting bar can be clamped in any required position by tightening the screw 33 so that the need for the clamping bars 22 of the previous embodiment is avoided.

As will have been appreciated, in both the above described embodiments, because the tube 1 is half filled with liquid, the free end surfaces of the liquid will lie on a diameter of the circle of the tube.

Advantageously, the scale is provided with at least one zero which is arranged to coincide with the diameter on which the free surfaces of the tiquid in the tube lie when the block is arranged with one of the side faces 5,6 vertical and the other horizontal.

The above described devices can be used in a number of different ways both as a level and for surveying and to demonstrate vertical, horizontal, angles of inclination and the principles of surveying.

With the front and back faces 7,8 of the block vertical, the side faces 5, 6 can be placed on surfaces whose inclination is required to be determined, the sighting bar then being aligned with the free end surfaces of the liquid in the tube. The surfaces may be planar or, for example, rods, which are then engaged in the appropriate groove 24 in the respective side face. Alternatively with the side faces 5, 6 horizontal and vertical, the sighting bar can be used in association with the scale alone to determine the elvation of a distant object.

With the front and back faces 7 and 8 in a horizontal plan, the operational features, sighting device, angular scale etc. uppermost, horizontal angles may be measured and a multiplicity or similar exercises undertaken.

Rings may be substituted for or mounted concentrip to the angular scale 14, these additional rings to be graduated with other scales. For example, a ring graduated in hours will permitthecomparison of scales of time and of arc.

It will be appreciated that, while the above described device has been designed as a teaching aid, it may also be used in practice to measure angles of inclination, elevation etc. A telescope or tube with suitable glass can be mounted on the sighting device permitting the observation of distant features such as a suveyor S graduated staff.

Claims (10)

1. A device being an aid for teaching and/or surveying comprising a hollow circular tube which is half filled with liquid, an angular scale associated with the tube and centred on the centre of the circle of the tube, and sighting means angularly movable over the scale and alignable with the free surfaces of the liquid in the tube.

2. A device as claimed in claim 1, wherein the sighting means has a linear edge which extends along a dimater of the scale and of the tube and is alignable with the free surfaces of the liquid in the tube.

3. A device as claimed in either claim 1 or claim 2, wherein the sighting means is in the form of a bar, one edge of which extends along a diameter of the scale and which has outturned ends which can be used for sighting a distant object.

4. A device as claimed in any one of the preceding claims, wherein the tube is mounted in a block which is provided with mutually perpendicular faces, parallel pairs of which extend parallel and perpendi culartothe plane of the tube.

5. A device as claimed in claim 4, wherein the block is provided with a central aperture in one face in which the tube is located and the sighting means is mounted on the block.

6. A device as claimed in claim 5, wherein linear grooves are provided in at least two mutually perpendicular faces of the block, the grooves extending in or parallel to the plane of the tube.

7. A device as claimed in either claim 5 or claim 6, wherein the scale is mounted on a ring which engages in the central aperture in the block and serves to retain the tube in the block, and the sighting means is provided with lugs engaging the inner surface of the ring to guide the sighting means in rotation.

8. A device as claimed in any one of claims 4 to 7, including releasable clamping means for clamping the sighting means relative to the block.

9. A device as claimed in claim 8, wherein the clamping means also serves to retain the sighting means relative to the block during rotation.

10. A device substantially as herein described with reference to the accompanying drawings.