Читать книгу Harper's Outdoor Book for Boys - Joseph H. Adams - Страница 36

An excellent and reliable wind indicator is shown in Fig. 7, the illustration of the wind-pennant. It consists of a metal hoop on which a funnel-shaped silk or cotton fabric pennant is sewed fast, and when this latter is filled by a breeze it stands out, as the illustration shows.

A pennant fifteen inches long should have a hoop five inches in diameter, and it can be made either from wire rings bent as shown in Fig. 8 A, or from sheet metal, as shown at Fig. 8 B.

The sheet metal should be perforated with small holes all around one edge to pass the thread through, when sewing the fabric fast, and the edges should be smoothed so as not to cut the threads. If the hoop is made of wire, a ring should be formed at top and bottom for the upright rod to pass through; but if it is of sheet metal a hole at the top and bottom will admit the rod.

This pennant is very useful at the mast-head of a boat, and is much more satisfactory to watch than the perpetually bobbing flat pennant, as it does not break or fall down unless it is calm, and only shifts from side to side as the wind blows it.

On a flag-pole or staff above the pennant the compass points are arranged, and if these are made from copper or brass, the letters may be soldered fast to the ends of the arms. Where the arms cross, they are to be flattened as shown in Fig. 9 A, and lapped together, as shown in Fig. 9 B. After the hole is bored they should be bound to the upright rod with copper wire and soldered so they will remain in a fixed position that the wind cannot alter. Fig. 9 C.

Sticks of hard wood may be substituted for the metal arms, and the sheet-metal letters let into saw cuts made at the outer ends.