Cask gauging.

Gauging timber.

herring, the gauge is to be a square gauge of 1 inch measured across each side of the square, or 4 inches measured round the four sides, no person, except as above provided, is to use in fishing for sea fish any net having a mesh through which a square gauge of 1 inch will not pass without pressure.

The Corporation of Colchester include in their Borough plate a silver oyster used as a standard of measurement for Colne oysters.

In gauging casks the following rods or rules are used :— A graduated head rod, for ascertaining the head diameter of the cask. This gauge serves also as a sliding rule for calculating the quantity of liquid in the cask.

A bung rod and dipping rod, for finding the bung diameter and diagonal of the cask.

Long callipers, used for finding the internal length of a cask from head to head. Short or cross callipers, for finding the external diameter of a cask. Stave gauge, for finding the thickness of the stave of a cask.

Measurements are generally made in feet and inches, rules for gauging casks are, as is well known, laid down in works on mensuration, &c.; for revenue purposes, excise officers are largely guided by rules given in the "Excise Officers' Manual."

The contents of beer casks are sometimes determined by weight.

The late Sir J. Lubbock, F.R.S., in a paper on "CaskGauging," which was reprinted in 1834 by Charles Knight from the "London and Edinburgh Philosophical Magazine,” states that Kepler was the first to endeavour to reduce the art of "gauging" to accurate principles in his work entitled "Nova Stereometria Doliorum Vinariorum. 1615."

In gauging timber quantities are usually ineasured and expressed in cubic feet run.

The gauging or measurement of timber at our ports is undertaken by timber measurers appointed by the

Directors of the Customs Annuity and Benevolent Fund, who are known as Customs Fund measurers. The rules for gauging are the same as those followed by the Customs Department before the duties on wood goods were abolished in 1866. The measurements by the Customs Fund officers appear in 1892 to have amounted to 600,000 loads for freight and sale purposes. The marking or scribing of the cubic contents on balk timber does not appear to be compulsory by Act of Parliament, and it is the practice of the measurers to scribe all large timber with a number corresponding to the records in their books of

measurement.

As an instance of the classification of timber for canal charges or tolls, it is sometimes provided in Canal Acts that "Forty cubic feet of oak, mahogany, teak, beech, "greenheart, ash, hickory, ironwood, baywood, or other

heavy timber, and 50 cubic feet of poplar, larch, fir, elm, birch, lancewood, walnut, or other light timber, other "than deals, battens, or boards, and 66 cubic feet of "deals, battens, and boards, shall be charged for as one "ton." A load of timber is generally taken as equal to 40 cubic feet of unhewn timber, or 50 feet of squared timber, or 600 superficial feet of 1-inch planks or deals.

gauges or

meters.

Gauges for measuring the height of water in a river or Water lake are of ancient origin, as the Nilometer of Egypt, and in modern times consist not only of a graduated rod or post but include a float and water tube, with magneto-electric means for indicating and recording the height of the water.

In the sale of water meters or gauges are used, but their use is not regulated by any public general Act of l'arliament. Local authorities and water companies, however, sometimes test water meters for use in their own district. Such instruments generally register in gallons, and are classified as positive meters and inferential meters, the former

Slide rules.

actually measuring the water passed, in a vessel of known capacity, while inferential meters infer the quantity passed by the revolutions imputed to a fan or turbine by the water as it passes through the meter (" The Water-Meter," W. G. Kent, London, 1892).

Forms of gauges known as 'slide rules are used in the mechanical measurement of work, or in checking measurements where approximate accuracy is needed, and where it is desired to solve at sight questions which depend on ratio. In an extended slide rule arranged by MajorGeneral Hannyngton the scale was so graduated in parts that a radius of 60, 120, and 240 inches might be obtained, and such a scale is said therefore to be equal in power to straight gauges of 10, 20, and 40 feet respectively. Gauges or slide rules, graduated to meet the requirements of particular trades, are also used, as the engineer's slide rule, rules for the calculation of embankment work, ditches, canals, and fortifications, or for setting out railway curves. Slide rules for logarithms, and sines, areas, diameters, and circumferences; slide rules of involution, giving the powers and roots of any given number, are also made. Rules are commonly used for the measurement of brickwork, curbing-stone, &c., and like the ordinary carpenter's slide rule, combine scales of parts of an inch with the logarithmic scales. In timber measurement special rules are used for finding the superficial or cubic contents of round and unequal-sided timber (St. Petersburg standard, &c.). Slide rules are used also for sheet-iron and steel measurements, or for rolling-mills, showing the lengths of bars of any size and form; for measuring volumes of gas, temperature effects, and barometric heights; for finding the weights of materials from their specific gravities; for determining breaking strains, and for general use in mechanical testings. Compound slide rules, arranged on "Gunter's lines," are used in solving problems in trigonometry and navigation.