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《测量评论》2013,45(17):138-147
AbstractWhile there is no standard method in stadia surveying of taking a set of readings for distance and altitude, the following may be regarded as the conventional, text-book method. The telescope is directed at the staff and the apparent lower hair brought to bear exactly on some convenient foot-mark. The readings of all three hairs are then taken and recorded (4.00, 5.41, and 6·83). Finally the vertical circle is read—to the nearest minute or to a fraction of a minute according to circumstances—and the result entered in the field-book (6° 31′ or 6° 31′ 20″). This method has its merits. It is straightforward and flexible and there is a simple (numerical) check on the accuracy of the staff-readings. Nevertheless it is by no means a perfect method. 相似文献
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《测量评论》2013,45(69):282-295
AbstractSurveying in, the sense in which I propose to consider it this evening, is the technical term given to the science of admeasuring and delineating the physical features of the earth and of works executed or proposed upon its surface. I am in some difficulty over a precise definition which will satisfy everyone since, although “surveying” is generally understood in the English language to have the above meaning, there is a growing tendency to use the somewhat restricted term” land survey"; restricted since it implies omission of hydrographic, hydrological and other forms of measurement of natural features and of setting out. This is, of course, not so. 相似文献
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《测量评论》2013,45(41):156-159
AbstractAs Mr H. F. Rainsford (E.S.R., no. 37, vol. v, July 1940) says, the ordinary accurate survey traverse, through its “ordinariness,” has been neglected in the printed word. The technique—perfected by much practice—has been handed down by word of mouth only from father to son, from surveyor to pupil. 相似文献
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《测量评论》2013,45(74):155-161
Abstract60. The three standard or field reference tapes are stored at the N.P.L., Teddington, and standardised to class “A” accuracy immediately before and after each base measurement. In order to reduce the residual contraction or “creep” of in var when exposed to higher temperatures, the tapes are retained for as short a time as possible in the Sudan and since 1945 they have been transported in both directions by air. In this way, any “creep” should be revealed by the standardisation after a measurement. From the formula of Dr. Guillaume the ultimate shortening, in the temperatures prevailing at Meheisa and Husheib, would have been ?26 and ?20 × 10?5 ft. respectively and it is clear from Table 3 that this tiresome source of uncertainty is largely eliminated by the procedure adopted. 相似文献
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《测量评论》2013,45(44):334-338
AbstractThe method of Garavito, Director of the Observatory of Bogota, consists in choosing two stars, one to the north of the zenith, the other to the south, such that the algebraical half-sum of their declinations may not differ much—at the limit 15′ or 20′—from the latitude of the place. As a matter of fact the difference may be slightly greater without inconvenience. 相似文献
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《测量评论》2013,45(18):203-218
AbstractThe gear used for the measurement of the Kate Base of the East African Arc was specially designed by McCaw in conjunction with Messrs. Cooke, Troughton, & Simms, as a result of considerable experience in the measurement of geodetic bases in Fiji, Sweden, and in various parts of Africa; it is now known by the trade name of the “Macca” Base Measurement Gear. It has since been used in Southern Rhodesia, Tanganyika, Mauritius, and South Africa, and if the central pool of instruments recommended at the recent Empire Surveyors Conference is approved, it seems likely that its beat will soon be still more extended. It must be about the only first model of a surveying instrument which has not occasioned widespread controversy and complaint, and for this desirable state of affairs it is not unreasonable to suppose that the rare co-operation between the practical surveyor and the instrument-maker in its design is responsible. 相似文献
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《测量评论》2013,45(40):69-75
AbstractWhen a theodolite is used to measure an angle, the result will be subjected to certain instrumental and personal errors which affect the measurement. Such errors may be accidental or systematic. Those of the former type, which follow no law and which may with equal probability occur at any graduation, are more easily eliminated, since, if a very large number of readings is taken, it is probable that the errors will cancel out and that the mean will approximate very closely to the correct figure. Systematic errors are usually due to instrumental defects and rnay be expressed as a function of the reading itself; it is the object of the manufacturer to eliminate these as far as possible, since cancellation by reiteration or by repetition is not to be expected wholly. 相似文献
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Abstract Azimuth.—The method was that of star altitudes in the prime vertical, except at X. 34 where hour angles on the P.V. were observed. At B.P. 79 and 99, NE. Terminal, and X. 12 and 34, the measures were made by Major Godfrey-Faussett or Capt. Taylor with the 8-inch C.T. & S. micrometer theodolite; and at all other stations by Capt. Taylor with the Tavistock theodolite Y. 2304. 相似文献
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《测量评论》2013,45(35):275-279
Abstract Triangulation.—Apart from Simms' Geodetic Chain, Gordon's Chain, the Copper Queen Limb, and a section of the Victoria and Umtali Series, all the primary triangulation shown on the accompanying map has been executed since 1933. The work of Simms and Gordon has been remodelled, however, being greatly strengthened, and these chains are now called Simms' and Gordon's Series. For an explanation and plan of the above Series, see “A Note on the Trigonometrical Survey of S. Rhodesia”, in the Empire Survey Review, no. 27, vol. iv. 相似文献
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《测量评论》2013,45(60):217-219
AbstractMap Projections.—A matter that should have been mentioned in the original article under this title (E.S.R., vii, 51, 190) is the definition of a map projection. In the list of carefully worded “Definitions of Terms used in Surveying and Mapping” prepared by the American Society of Photogrammetry (Photogrammetrie Engineering, vol. 8,1942, pp. 247–283), a map projection is defined as “a systematic drawing of lines on a plane surface to represent the parallels of latitude and the meridians of longitude of the earth or a section of the earth”, and most other published works in which a definition appears employ a somewhat similar wording. This, however, is an unnecessary limitation of the term. Many projections are (and all projections can be) plotted from rectangular grid co-ordinates, and meridians and parallels need not be drawn at all; but a map is still on a projection even when a graticule is not shown. Objection could be raised also to the limitation to “plane surface”, since we may speak of the projection of the spheroid upon a sphere, or of the sphere upon a hemisphere. Hence, it is suggested that “any systematic method of representing the whole or a part of the curved surface of the Earth upon another (usually plane) surface” is an adequate definition of a map projection. 相似文献
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《测量评论》2013,45(11):258-264
Abstract The Ordnance Survey and the War.—I shall not inflict upon the readers of this Review any very long account of the work of the Ordnance Survey during the Great War. At that time the work of the Survey suffered from one necessary disadvantage: all the young men on its establishment, whether in the R.E. Companies or on the Civil Staff, left for active service. As a slight compensation for this inevitable dislocation all money difficulties in the preparation of maps for war disappeared. 相似文献
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AbstractCadastral Traversing.—For cadastral purposes traverses are now being executed with an accuracy wholly unnecessary for even large topographical scales. But since “accuracy” varies from a mile to a micron, according to the viewpoint of the observer, it is advisable to exhibit a cadastral traverse, care being taken that it is not an example of that not very uncommon occurrence in which fortuity apes precIsIon. If the accuracy of the example is somewhat unusual, it can be said with assurance that it is not very unusual. 相似文献
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Abstract19. Formulae.—In Nos. 6, vol. i, and 9, vol. ii, pp. 259 and 156, there has been described a new method for dealing with long geodesics on the earth's surface. There the so-called “inverse” problem has claimed first attention: given the latitudes and longitudes of the extremities of a geodesic, to find its length and terminal azimuths. It remains to discuss the “direct” problem : a geodesic of given length starts on a given azimuth from a station of known latitude and longitude; to find the latitude and longitude of its extremity and the azimuth thereat. The solution of this direct problem demands a certain recasting of the formulae previously given. In order of working the several expressions now assume the forms below. 相似文献
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《测量评论》2013,45(78):338-348
AbstractRadar can be applied to surveying for precise measuren1ent of long lines, and as a navigational aid and position-fixing device for an aircraft performing a photographic survey. Trials of the radar method have recently been carried out in Australia using a modified “Shoran” equipment. The results of a large number of radar measurements of six distances, varying from 160 to 310 miles in length, indicate that an accuracy of 7 parts in 105 can be achieved. Equipment errors constitute the immediate limit to accuracy, but reasonable modifications would yield a figure of 2 parts in 105. Radar measurements can be completed in a fraction of the time required by normal ground survey methods, since a measurement of upwards of a hundred miles is made in a single step.As an aid to photographic surveying a straight-line track indicator actuated by data from the “Shoran” equipment has been designed and flight tested. Its performance enabled a pilot taking aerial photographs to keep the aircraft to within an average departure of less than 0.02 mile from any desired straight-line flight path. 相似文献
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《测量评论》2013,45(14):472-484
Abstract Choice of Beacon.—The general question as to whether luminous or opaque signals should be used in ruling triangulation has recently been discussed in the Empire Survey Review (No.9, pp. 151–2 and No. 12, pp. 335–6). It may here be summarized that opaque beacons of suitable design are sufficiently accurate and offer the considerable advantages of being immediately available for subsequent work, of requiring little or no attention, and of being visible from all directions without rearrangement. Moreover, if of the tripod or quadripod type, they need not be dismounted during occupation of the station for observing, so that 0bservations by more than one observer are not interrupted. The only occasion for using luminous beacons arises from bad visibility, whether through atmospheric haze or lack of a suitable background or through the economic necessity of completing observations at night. These conditions are not peculiar to ruling triangulation. An ”all-round” type of luminous beacon—a pressure oil lamp or a rotating mirror system—can be used for nightwork or against a dark background, but single-direction luminous beacons are necessary to overcome haze. 相似文献
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Abstract The Arc of the Geodesic.—In the first part of this paper a method was given for computing the azimuth of a geodesic. The method gives the convergence of the geodesic correctly up to the second power of e the eccentricity. The formula (9), however, also depends on the assumption that σ, the arc-length of the geodesic, can be obtained with sufficient accuracy from the Supplemental Dalby Theorem, that is to say, by a purely spherical computation. It is, therefore, needful to show that this supposition is justifiable; a means must in fact be indicated for verifying the assumption. 相似文献
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AbstractA Fully equipped theodolite is provided with plate levels, an alidade level, and a striding level. An instrument not so equipped has no title to be considered a “Universal Instrument”, that is to say, an instrument designed for every kind of both terrestrial and celestial measurement. Without a striding level, for example, nothing beyond relatively rough astronomical measures can be expected in general. Modern instruments, capable of giving considerable refinement in terrestrial measures, are frequently not furnished with a striding level; and it is sometimes assumed, with the tacit approval of the makers, that such instruments are equally capable of giving refined astronomical results. On the older type of instrument a striding level—rarely not supplied—could have been, and sometimes was, extemporized; it seems as if ignorance of astronomy of position has led, at least in part, to the construction of theodolites in such a manner as actually to render such extemporization difficult. 相似文献
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Abstract1. Some Preliminary Considerations.—Let it be supposed that an iceberg is captured by an ice-field. It will be assumed that the field can be packed, either by opposing currents or by pressure against a land mass on one side. Compared with the vertical dimension of the berg the thickness of the field will be comparatively small. 相似文献