In order to effect a repair it is merely necessary to clean the broken ends of the band, and insert them into the sleeve, then hold a lighted match under it until the soldering material is melted, when the repair is completed.
The central hole in the sleeve is to enable the user to see when the broken ends are in contact, and the other two are to indicate when the soldering material is melted, which takes place when it either bubbles up in or runs away from these holes.
Fig. 349.—Linen Tape.
Fig. 350.—Small steel pocket tape.
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746.—Linen Tapes.—This most useful implement, Fig. 349, is one of the most unsatisfactory measures the trader and user has to do with. It consists, as is well known, of a tape oiled, painted, and varnished, which is rolled up in a leather case when out of use. When the weather is moist it shrinks, and when dry it expands. If it be too heavily painted it becomes brittle and rotten; if it be lightly painted it remains more flexible, but is more affected by moisture. A good tape bears very well a stretching force of 7 lbs. to 14 lbs., but if strained over this it is permanently stretched. There is no plan known to the author by which these defects can be remedied. Numerous attempts have been made—often valueless or worse—some, although popular, mere claptraps, such as the insertion of wire. The best tapes for strength and permanency are made entirely of green, hand-made, unbleached flax. The tape is said to come from Holland to this country. These are at first oiled with a drying oil (boiled linseed oil), and when seasoned for a month or so, painted once or twice with white lead colour—not too thickly. The printing is more permanent if done in oil; but the tape is somewhat more flexible if the figures are stencilled in Indian ink and the whole afterwards thinly varnished over with copal varnish. The great secret for preserving the tape is to use it very carefully and only in fine weather. In wet weather for taking offsets a light steel 50-link chain is quite as convenient as the tape, and safer.
Tapes are divided into links, feet and inches, metres, and all measures as required. A decimal yard is commonly placed on tapes for measuring earth work. For use with the chain a 66-feet tape is usually employed, but many think a 33-feet better, using the chain for dimensions above this. For measuring buildings, 50-feet or 100-feet tapes subdivided to inches are employed.
747.—Steel Tapes.—Thin steel tapes, 3/8, ½, and 5/8 inch wide are in very extensive use. They are more accurate and more costly than linen tapes, but less flexible and less durable. Where dimensions are important they should always be used for short measurements. In all cases it is advisable for a surveyor to keep a steel tape for examination of the lengths of linen tapes in use. They are made to all the measurements of linen tapes.
748.—Pocket Steel Tapes 6 feet to 12 feet, Fig. 350, are used more generally by mechanical engineers. These tapes, which are very light, are held open by a catch, and closed by a spring.