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90.15 - Surveying (including photogrammetrical surveying), hydrographic, oceanographic, hydrological, meteorological or geophysical instruments and appliances, excluding compasses; rangefinders. 90 15.10 - Rangefinders 90 15.20 - Theodolites and tachymeters (tacheometers) - Levels 90 15.40 - Photogrammetrical surveying instruments and appliances 90 15.80 - Other instruments and appliances 9015.90 - Parts and accessories 9015.30 (I) INSTRUMENTS AND APPLIANCES USED IN GEODESY, TOPOGRAPHY, SURVEYING OR LEVELLING These are generally intended for use in the field, for example, in cartogra hy (land or hydrographic maps); in the preparation of plans; for triangulation measurements; or calculating the area of a piece of land; in determining heights above or below some horizontal reference level; and for all similar measurements in constructional work (building roads, dams, bridges, etc.), in mining, in military operations, etc. P This group includes : Fb, (I) Optical or opto-electronic theodolites (vernier reading, microscope, suspended (wall-stand universal, mining, etc., types), optical or opto-electronic tachyrneters tac eometers) (theodolites incorporating a rangefinder), transits, gyrotheodolites, compass-clinometers, sighting clinometers for use in survey or artillery, etc. (2) Optical levels (spirit, autoset, telescopic, collimator, laser, etc.), generally used mounted on a tripod. (3) Alidades (whether or not with a telescope), o tical s uares and cross-staffs (whether or not with prism) and pantometers (with or without si&ting telescope), clinometers (with a collimator or si ting telescope), used to determine gradients and inclines, mining dials, graphometers, he iostats for trigonometrical survey, etc. ? (4) Plane tables, land chains and other special measures for surveyin band-measures specialised thereto, winch- e measures for mine-shafts, ranging oles, whether or not graduate (of metal, wood, etc.), self-read&, telescopic, folding, etc.), electromagnetic distance [EDM) reflector prisms and poles. This heading does not cover : (a) Global positioning system (GPS) receivers (heading 85.26). (b) Measuring instruments consisting of a steel band, waterproof tape, etc., and similar unspecified devices for taking linear measurements (heading 90.17). (c) Revolution counters, mileorneters and the like (heading 90.29). (d) Levels (air bubble type, etc.) used in building or constructional work (e.g., by masons, carpenters or mechanics), and plumb-lines (heading 90.31). (11) PHOTOGRAMMETRICAL INSTRUMENTS AND APPLIANCES These are mainly used for plottin topographic, archaeologic, etc., maps, but they are also used for other urposes (e$.,. study o tides, ground-swells, etc.). The maps, etc., are plotted from or digit Images taken fkom two diffennt viewpoints a known distance apart, which must then be "restituted" (to obtain accurate information in respect of the shape, size and co-ordinates of objects in the image or photograph). ? This apparatus consists essentially of: (1) The " erecting " apparatus consisting mainly of a projector (with a light source), a negative-carrier, an objective and a pro'ection table. This apparatus enables the scale to be changed, and it can also photographca ly correct negatives of aerial photographs which, in practtce, contain errors in perspective, etc., due to variations in the terrain. r' (2) Restitution a paratus (stereoplotting apparatus or photogoniometers) also called stereotopograp s, stereoplanigraphs, " autographs ", stereoplotters, stereocornparators, etc. These are complex ap aratus used to plot the planigraphic details and contour lines constitutin a map or p an, this operation generally being done continuously and without separate ca culation. R P k (3) Co-ordinatogra hs of the t e used with restitution apparatus; these bear the map on which the penci controlledYgy the stereotopograph or the stereoplanigraph traces its indications. P (4) Analytical stereomeasurin systems which consist of an o tomechanical apparatus, operated photogrammetrical y, and a programmed calculator. T ese systems are used for vlsual or analytical interpretation of photographic or digital images. ? !i But the headin excludes aerial survey photo aphic cameras (heading 90.06), and co-ordinatographs not designed for p otografnmetric uses (headi11~F0.17). t (111) HYDROGRAPHIC INSTRUMENTS H drography is the scientific description and plotting of water courses, depths, tide levels, etc. ~ z majority e of the instruments used for such purposes are, therefore, covered by the previous paragraphs. (IV) OCEANOGRAPHIC OR HYDROLOGICAL INSTRUMENTS (1) Special level recorders, for recording fluctuations in the level of lakes or rivers; they consist essentially of a float and recorder. (2) Bucket-wheel current meters and hydrometric paddle-wheels, for measuring the speed of currents in rivers, canals, etc. (3) Swell or tide recorders. Industrial instruments based on the same workin principles as the instruments described in para a hs IV) (1) and (2) above (e.g., liquid level in icators, flow meters, etc.) are, however, exc$u #ed heading 90.26). i (V)~ T E O R O L O G I C A LINSTRUMENTS It should be noted that this group does not cover thermometers, barometers, hygrometers and psychrometers, nor combinations of such instruments (heading 90.25). The group does, however, include the following : (1) Wind direction indicators, whether or not fitted with dials. (2) Anemometers, i.e., meteorological instruments for measuring wind speed. One type consists of a rotor carrying three cu -shaped blades mounted on a vertical axis, readings being obtained by a counter. The o er most common type consists of a kind of weather vane fitted with a tube in which the wind pressure is measured by a differential pressure gau e graduated in speed units. The grou also covers anemometers in which a enerator pro uces a fluctuating voltage which ish! en indicated on a voltmeter calibrate in wind speed. % f f' It should be noted that special types of anemometers, for measuring the s eed of air currents in mines, tunnels, chimneys, furnaces or other air passages, consisting essenti ly of a special type of fan and a dial, are excluded (heading 90.26). S (3) Evaporation meters (Piche, evaporation balance types, etc.). (4) Sunshine recorders (glass sphere, sensitised paper types, etc.). (5) Nephoscopes, for indicating the speed and direction of movement of clouds. (6) Ceilometers, for determining the height of the cloud ceiling above the earth by indicatin the angular elevation of a spot of li t formed where a stron beam of light meets the clou so that the height may be computed? automatically by triangu ation. f' % (7) Visibilir. meters, for measuring meteorological visibility or the capability of air to transmit ~ght. (8) Rain gau es and indicators, for measuring rainfall in a particular place. The simplest t e consists o a funnel of known diameter fixed to a receptacle to collect the rain which is t en measured in a calibrated tube. ! F (9) Actinometers, solarimeters and pyrheliometers, for measuring the intensity of solar rays or the total radiation received fiom the sky. It should, however, be noted that the heading excludes simple or combined thermometers used for the same purpose (heading 90.25). (10) Aerological sounding apparatus (radio-sonde or radio-wind apparatus) for suspending ftom a balloon or parachute. Such apparatus consist of instruments (thermometer, barometer and hygrometer) for high altllde research work, combined with a wireless transmitter enabling the instrument readings to be automatically recorded on the ground. When separately presented, the balloons and parachutes are excluded (Chapter 88). (1 1) Theodolites for recording successive positions of sounding balloons. (VI) GEOPHYSICAL INSTRUMENTS Many geophysical instnunents are excluded, for example, gas, sludge or soil analysis apparatus, photoelectric fluororneters and fluoroscopes (instruments using ultra-vioIet light to detect or identifl numerous substances) (heading 90.27); electric or electronic measurin instruments (e. ., instruments for measuring resistivity, radioactivity counters, thermocouple instruments7(heading 90.307~=to. The following remain in this heading : (1) Seismometers and seismographs, for record in^ the time, duration and intensity of movements of a point on the earth's crust, and seismometers and seismographs used both for recording the various phenomena occurring during earthquakes, and in prospectin for mineral oil. In these instruments the seismic waves set up by an earthquake, or by the ring of an explosive charge, are converted into electric impulses. B (2) Magnetic or gravimetric geophysical instruments used in prospecting for ores, oil, etc. These highly sensitive instruments include magnetic balances, magnetometers, magnetic theodolites and gravimeters, torsion balances. (3) Electronic ma netic gradiometers (also known as "proton magnetometers") which measure the gra ient of the earth's magnetic field. % 'P (4) Circumferential acoustic scanning tools which create a icture" of a borehole by measuring the acoustic travel time of an ultrasonic signa emitted from a rotating transducer in the head of the tool. (5) Apparatus for measuring the inclination of a borehole. (VII) RANGEFINDERS This group covers all types of optical or opto-electronic rangefinders for determining the distance between the instrument and a given object. They are used in surveying, photography and cinematography, by the armed forces, etc. PARTS AND ACCESSORIES Subject to the provisions of Notes 1 and 2 to this Chapter (see the General Explanatory Note), this heading also covers parts and accessories of the goods of this heading. Such parts and accessories include : tripods s ecially designed for instruments used in geodesy, topography, etc.; supporting rods for optica squares; tripods for staves; arrows for land chains. l'