Dumpy Level

It is a short and stout instrument with rigidly telescope tube associated to the vertical spindle. Therefore in vertical plane the level tube can't move. It can't be removed from its support. Therefore its name is dumpy level. In the horizontal plane the telescope rotates in the socket of the levelling head. A bubble tube is attached to the top of the telescope. Given figure shows a typical dumpy level. Described Plate shows its photograph.

                 Plate Dumpy level

1. Telescope                                     7. Bubble tube adjusting screws

2. Eyepiece                                       8. Diaphragm adjusting screws

3. Shade                                           9. Focusing screws

4. Objective end                                10. Foot screws

5. Longitudinal bubble tube                 11. Upper parallel plate (tribrach)

6. Transverse bubble tube            12. Foot plate (Trivet stage)

                                                      Dumpy level

With object glass and eyepiece Telescope is a tube. Object glass may be adjusted by using the focussing screw on the object before sighting the graduated staff held. By rotating it Eyepiece may be adjusted to see that parallel is removed and cross hairs appear distinctly. Eyepiece once adjusted requires no change as long as the similar person takes the readings.

With slightly curved shape provided over the level tube Level tube is a glass tube. The tube is filled with alcohol or ether leaving a little air gap, which takes the shape of a bubble. Always the air bubble is at the highest point. Level tube is fixed with its axis parallel to telescope tube, so that while bubble is centred, the telescope is horizontal. Tube is graduated on either side of its centre to estimate how much the bubble is out of centre. Inside a brass tube the glass tube is placed which is open from top and on lower side. By means of capston headed nuts it is fixed to telescope tube. If it is out of order, the bubble tube is adjusted with these nuts.

 Levelling head consists of 2 parallel plates with three foot screws. Upper plate is called as tribratch plate and the lower one as the trivet. Lower plate may be screwed on to the tripod stand. The instrument can be levelled to get perfect horizontal line of sight by adjusting the screws.

To use it in the field Dumpy level is to be fitted to a tripod stand. Tripod stand consists of three legs connected to a head to which the lower plate of level may be fitted. With metal shoes to get good grip with ground the lower side of the legs are provided. Described Plate shows typical level stands.

            Levelling stands (non-adjustable and adjustable)