Fig. 411.—Footner's railway gauge and clinometer.
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855.—Railway Gauge, combining level and clinometer. This high-class gauge, Fig. 411, is the invention of Mr. H. Footner, C.E., late of the London and North-Western Railway. It is formed of a bar of Spanish mahogany neatly shaped. The end fittings are of steel. The gauging part is formed of two turn-up steel flap-pieces with back stops. A spirit level is sunk in the end fitting, shown in the figure towards the left hand. The clinometer is formed by a gun-metal pin of ½ inch in diameter; 9 inches long. This slides perpendicularly in a spring fitting sufficiently stiff to support the gauge, and is made to fall on the centre of the rail. The pin is divided into inches and eighths. When it is out of use it slides up the end of the gauge and leaves the whole instrument smooth and portable to carry open or go into a leather case. Its use is implied.
856.—Timber Girth Strap.—The direction for removal and estimate of the value of timber often falls into the hands of the surveyor. The height of standing timber may be taken by a long rod, or a pair united by a link, [art. 775], or by the apomecometer, [art. 693]. The girth is most conveniently taken by a leather girth strap, of which there are various patterns: but that illustrated below, Fig. 412, is perhaps the most popular form. This strap is made of two straps of bullock's hide 1 inch wide, thinned down to about 1/8 inch in thickness; the two pieces are stitched together to make it 12 feet to 14 feet long. The strap is divided by lines into inches, but figured in units at every 4 inches = single inches of quarter-girth. The figures and lines are stamped. A brass weight, shown at one end of the strap, is thrown by the strap with a swing round the standing tree, and encompasses it in a second of time. The weight is caught by the hand and the strap brought up to it to read the quarter-girth. The quarter-girth gives roughly the equal sides of a square; as, for instance if a quarter-girth reads 10, the size of the tree is 10 × 10 = 100 inches, or 8·4 cubic foot-inches per foot run.
Fig. 412.—Leather girth strap with throwing reel.
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Some surveyors prefer a hook instead of a weight, as being more convenient to measure close timber. This is shown Fig. 413. The hook is stuck into the bark and the tree is girthed by walking round until the hook is met.
