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accuracy accurate adjustment altitude angle axis barometer base bearing bench marks bubble calculated centre centre line chain line Chapter closing collimation compass contours correct cross hairs cross sections Crown 8vo curve described determined difference direction distance division elevation engineer equal error Feet fence field fixed given gives glass ground height horizontal instrument latitude length longitude lower mark mean measured meridian method metres miles minutes moved nearly necessary object observed ordinary parallel placed plate plotted position possible practice railway ranging reading reduced result Road rule scale screws shown in Fig side sight slope square staff star station surface survey taken tangent tape telescope temperature theodolite traverse triangle tube tunnel upper usually vernier vertical wire
Page 88 - All the interior angles of any rectilineal figure, together with four right angles, are equal to twice as many right angles as the figure has sides.
Page iii - SURVEYING AS PRACTISED BY CIVIL ENGINEERS AND SURVEYORS. Including the Setting-Out of Works for Construction and Surveys Abroad, with many Examples taken from Actual Practice. A Handbook for use in the Field and the Office, intended also as a Text-book for Students. By JOHN WHITELAW, Jun., AMInst.CE, Author of
Page 203 - This may be done by summing up the readings and noticing the length of the bubble. In reading the level by means of the mirror care should be taken that the position of the eye is such that there will be no parallax. Such positions can be determined once for all when the mirror is at its greatest angle of elevation, by...
Page 219 - Adjustment of Level. the staff reading at B should be. If now the actual staff reading at B does not agree with this, raise or depress the whole instrument by means of the levelling screws s, s, Fig. 104, until the reading at B is correct. Now bring the bubble to the centre of its run by means of the adjusting capstan screws at e connecting the level with the telescope. See now if the reading of the staff at A is altered, and if not, the adjustment is correct. If the reading at A is altered, the...
Page 470 - The extremity of each tape length will be marked on the zinc strips with a fine line and suitably numbered. The preservation of these strips furnishes a ready means of comparison of each tape length at any future time. The line should be measured two or more times, with a discrepancy when reduced of not more than I in 250,000.
Page 202 - ... being estimated; and finally the level will be read again. The observer will then read the rod a second time to make sure that no error has been made. The recorder will then take the differences between the readings of the middle and extreme wires to guard against errors, and if these differences denote any error the observations must be repeated. If an error exists it will be shown by too great a difference between the differences. This is a most important check and must not be neglected. These...
Page 383 - Greenwich mean time corresponding to this observed right ascension of moon's limb is then to be deduced by interpolating between the registered values of moon's right ascension in the Nautical Almanac. The longitude in time is then deduced from the difference between the local mean time and Greenwich mean time of the observation, and then converted into degrees. The Greenwich mean times of the occultations of fixed stars by the moon are given in the Nautical Almanac for both immersion and emersion....
Page 224 - ... shall be added of any building, yard, court-yard, or land within the curtilage of any building, or of any ground cultivated as a garden...
Page 199 - ... in order to change the position of the threads on the rod. Taking the mean of the ten observed differences of readings of the extreme threads at each station occupied by the rod, a table will be constructed giving in metres the distance of the rod from the instrument for any observed difference of reading between extreme wires.
Page 203 - Property corners should be utilised where practicable. In addition to the above, benches should be established on permanent brick or stone structures by leading into them a horizontal copper bolt, with the letters USPBM and the number of the bench mark cut near it.