What is "tide gauge"

Gauge \Gauge\, n. [Written also gage.]

1. A measure; a standard of measure; an instrument to determine dimensions, distance, or capacity; a standard.

   This plate must be a gauge to file your worm and groove to equal breadth by.
   --Moxon.

   There is not in our hands any fixed gauge of minds.
   --I. Taylor.

2. Measure; dimensions; estimate.

   The gauge and dimensions of misery, depression, and contempt.
   --Burke.

3. (Mach. & Manuf.) Any instrument for ascertaining or regulating the dimensions or forms of things; a templet or template; as, a button maker's gauge.

4. (Physics) Any instrument or apparatus for measuring the state of a phenomenon, or for ascertaining its numerical elements at any moment; -- usually applied to some particular instrument; as, a rain gauge; a steam gauge.

5. (Naut.)

   1. Relative positions of two or more vessels with reference to the wind; as, a vessel has the weather gauge of another when on the windward side of it, and the lee gauge when on the lee side of it.

   2. The depth to which a vessel sinks in the water.
      --Totten.

6. The distance between the rails of a railway.

   Note: The standard gauge of railroads in most countries is four feet, eight and one half inches. Wide, or broad, gauge, in the United States, is six feet; in England, seven feet, and generally any gauge exceeding standard gauge. Any gauge less than standard gauge is now called narrow gauge. It varies from two feet to three feet six inches.

7. (Plastering) The quantity of plaster of Paris used with common plaster to accelerate its setting.

8. (Building) That part of a shingle, slate, or tile, which is exposed to the weather, when laid; also, one course of such shingles, slates, or tiles. Gauge of a carriage, car, etc., the distance between the wheels; -- ordinarily called the track. Gauge cock, a stop cock used as a try cock for ascertaining the height of the water level in a steam boiler. Gauge concussion (Railroads), the jar caused by a car-wheel flange striking the edge of the rail. Gauge glass, a glass tube for a water gauge. Gauge lathe, an automatic lathe for turning a round object having an irregular profile, as a baluster or chair round, to a templet or gauge. Gauge point, the diameter of a cylinder whose altitude is one inch, and contents equal to that of a unit of a given measure; -- a term used in gauging casks, etc. Gauge rod, a graduated rod, for measuring the capacity of barrels, casks, etc. Gauge saw, a handsaw, with a gauge to regulate the depth of cut. --Knight. Gauge stuff, a stiff and compact plaster, used in making cornices, moldings, etc., by means of a templet. Gauge wheel, a wheel at the forward end of a plow beam, to determine the depth of the furrow. Joiner's gauge, an instrument used to strike a line parallel to the straight side of a board, etc. Printer's gauge, an instrument to regulate the length of the page. Rain gauge, an instrument for measuring the quantity of rain at any given place. Salt gauge, or Brine gauge, an instrument or contrivance for indicating the degree of saltness of water from its specific gravity, as in the boilers of ocean steamers. Sea gauge, an instrument for finding the depth of the sea. Siphon gauge, a glass siphon tube, partly filled with mercury, -- used to indicate pressure, as of steam, or the degree of rarefaction produced in the receiver of an air pump or other vacuum; a manometer. Sliding gauge. (Mach.)

   1. A templet or pattern for gauging the commonly accepted dimensions or shape of certain parts in general use, as screws, railway-car axles, etc.

   2. A gauge used only for testing other similar gauges, and preserved as a reference, to detect wear of the working gauges.

   3. (Railroads) See Note under Gauge, n., 5. Star gauge (Ordnance), an instrument for measuring the diameter of the bore of a cannon at any point of its length. Steam gauge, an instrument for measuring the pressure of steam, as in a boiler. Tide gauge, an instrument for determining the height of the tides. Vacuum gauge, a species of barometer for determining the relative elasticities of the vapor in the condenser of a steam engine and the air. Water gauge.

      1. A contrivance for indicating the height of a water surface, as in a steam boiler; as by a gauge cock or glass.

      2. The height of the water in the boiler.

         Wind gauge, an instrument for measuring the force of the wind on any given surface; an anemometer.

         Wire gauge, a gauge for determining the diameter of wire or the thickness of sheet metal; also, a standard of size. See under Wire.

Tide \Tide\, n. [AS. t[=i]d time; akin to OS. & OFries. t[=i]d, D. tijd, G. zeit, OHG. z[=i]t, Icel. t[=i]?, Sw. & Dan. tid, and probably to Skr. aditi unlimited, endless, where a- is a negative prefix. [root]58. Cf. Tidings, Tidy, Till, prep., Time.]

1. Time; period; season. [Obsoles.] ``This lusty summer's tide.''
   --Chaucer.

   And rest their weary limbs a tide.
   --Spenser.

   Which, at the appointed tide, Each one did make his bride.
   --Spenser.

   At the tide of Christ his birth.
   --Fuller.

2. The alternate rising and falling of the waters of the ocean, and of bays, rivers, etc., connected therewith. The tide ebbs and flows twice in each lunar day, or the space of a little more than twenty-four hours. It is occasioned by the attraction of the sun and moon (the influence of the latter being three times that of the former), acting unequally on the waters in different parts of the earth, thus disturbing their equilibrium. A high tide upon one side of the earth is accompanied by a high tide upon the opposite side. Hence, when the sun and moon are in conjunction or opposition, as at new moon and full moon, their action is such as to produce a greater than the usual tide, called the spring tide, as represented in the cut. When the moon is in the first or third quarter, the sun's attraction in part counteracts the effect of the moon's attraction, thus producing under the moon a smaller tide than usual, called the neap tide.

   Note: The flow or rising of the water is called flood tide, and the reflux, ebb tide.

3. A stream; current; flood; as, a tide of blood. ``Let in the tide of knaves once more; my cook and I'll provide.''
   --Shak.

4. Tendency or direction of causes, influences, or events; course; current.

   There is a tide in the affairs of men, Which, taken at the flood, leads on to fortune.
   --Shak.

5. Violent confluence. [Obs.]
   --Bacon.

6. (Mining) The period of twelve hours. Atmospheric tides, tidal movements of the atmosphere similar to those of the ocean, and produced in the same manner by the attractive forces of the sun and moon. Inferior tide. See under Inferior, a. To work double tides. See under Work, v. t. Tide day, the interval between the occurrences of two consecutive maxima of the resultant wave at the same place. Its length varies as the components of sun and moon waves approach to, or recede from, one another. A retardation from this cause is called the lagging of the tide, while the acceleration of the recurrence of high water is termed the priming of the tide. See Lag of the tide, under 2d Lag. Tide dial, a dial to exhibit the state of the tides at any time. Tide gate.

   1. An opening through which water may flow freely when the tide sets in one direction, but which closes automatically and prevents the water from flowing in the other direction.

   2. (Naut.) A place where the tide runs with great velocity, as through a gate. Tide gauge, a gauge for showing the height of the tide; especially, a contrivance for registering the state of the tide continuously at every instant of time. --Brande & C. Tide lock, a lock situated between an inclosed basin, or a canal, and the tide water of a harbor or river, when they are on different levels, so that craft can pass either way at all times of the tide; -- called also guard lock. Tide mill.

      1. A mill operated by the tidal currents.

      2. A mill for clearing lands from tide water.

         Tide rip, a body of water made rough by the conflict of opposing tides or currents.

         Tide table, a table giving the time of the rise and fall of the tide at any place.

         Tide water, water affected by the flow of the tide; hence, broadly, the seaboard.

         Tide wave, or Tidal wave, the swell of water as the tide moves. That of the ocean is called primitive; that of bays or channels derivative. See also tidal wave in the vocabulary.
         --Whewell.

         Tide wheel, a water wheel so constructed as to be moved by the ebb or flow of the tide.

alt. A gauge for showing the height of the tide, particularly one continuously updated. n. A gauge for showing the height of the tide, particularly one continuously updated.

A tide gauge (also known as mareograph or marigraph) is a device for measuring the change in sea level relative to a datum.

Sensors continuously record the height of the water level with respect to a height reference surface close to the geoid. Water enters the device by the bottom pipe (far end of the tube, see picture), and electronic sensors measure its height and send the data to a tiny computer.

Historical data are available for about 1,450 stations worldwide, of which about 950 provided updates to the global data center since January 2010. At some places records cover centuries, for example in Amsterdam where data dating back to 1700 is available. When it comes to estimating the greater ocean picture, new modern tide gauges can often be improved upon by using satellite data.

Tide gauges are used to measure tides and quantify the size of tsunamis. The measurements make it possible to derive the mean sea level. Using this method, sea level slopes up to several 0.1 m/1000 km and more have been detected.

A tsunami can be detected when the sea level begins to rise, although warnings from seismic activity can be more useful.