The best levels have adjustable vials

The best levels have adjustable vials. Longer spirit levels are more accurate, although small ones can be useful in odd corners. Check that any pair are the same level by laying the batten across their tops and driving one in to correct any tilt. One way to extend the reach of any spirit level is to set it on top of a straight batten or board. There;s no need to go to the trouble of marking all the graduations: just make a single mark at each end with tape. For things like erecting a fence, a line level is the most convenient. Although most can stand up to a fair amount of knocks, it;s important to take good care of your level.

You can buy plumblines, but all they are is a weight on the end of a piece of string - so you can make your own with something like a bolt for the weight. For jobs like laying concrete, you can make use of levelling stakes - lengths of wood driven into the ground. It;s important that the body is rugged, as the level;s accuracy depends on it being even and straight. Here you need to draw a line. To ensure that two points further apart are at the same level, you can use a water level. The vials are usually quite delicate and may be broken or moved out of position, upsetting the accuracy. The principle holds true for any distance, no matter where the tube in the middle goes. But although this is fine for things which are straight and rigid, it isn;t so easy if you are trying to hang something flexible, like a Precision screwdriver set manufacturers wall-covering.

This is simply a small spirit level designed to hook into a piece of string held taught between two points. If you repeat this for each pair in turn, you can establish a level over a wide area. But it;s really important that the batten you use is really straight, and that it is an even thickness, otherwise it will introduce inaccuracies. Colour the water to make it easy to see. If you hold the string up and let the weight swing free, it will find it;s own vertical. To use one - to level two posts for example - get an assistant to help you hold the end against the post tops and then adjust the posts; height until the level of the water is against the same graduation at both ends. Check by sighting along from the end. Most ordinary spirit levels have a second vial set upright across the body. When it stops swinging, tape it to stop it moving and rule a line down the string or chalk it and snap against the wall. When the bubble is centred in this, the body is vertical. The answer is to use a plumbline - and you can use this for other jobs too if you don;t have a spirit level.

This is essentially just a tube filled with water, but the ends of the tube are transparent and have graduations marked on them. To check that a level is accurate, lay it down on a flat surface, then turn it round in the opposite direction - you should get the same reading both times.A spirit level is a tool you will use again and again - so it makes sense to buy the best you can afford.. Most levels have more than one tube (vial) so that they can be used at different angles. You can easily make your own water level from a length of old garden hose with some clear plastic tube rammed in at either end