## Outline of the Method of Conducting a Trigonometrical Survey, for the Formation of Geographical and Topographical Maps and Plans: Military Reconnaissance, Levelling, EtcWeale, 1850 - 253 pages |

### From inside the book

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**intersection**remaining constantly fixed upon some minute , well - defined , distant point , during an entire revolution of the telescope upon its own axis in the Ys , which are left open for the purpose . When this**intersection**on the ... Page 27

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**intersection**of which with 00 ' gives the point T ' , which is approximately the lost station required . Only two triangles are shown in the diagram , to prevent confusion , but three at least ought to be employed to verify the**intersection**... Page 28

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**intersection**T ' of the lines 1 1 ' and 22 ' , and from this diagram the angle formed at T with this point T ' , and the line drawn in the direction of any of the stations A , B , or C , can be taken , as also the distance TT ' ; the ... Page 43

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**intersections**with the theodolite , either from the extremities of these lines or from such intermediate points as appear best adapted for determining their positions . These points when plotted , together with the offsets * from the ... Page 46

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**intersection**of these lines gives the re- quired place of observation . be Instead of the above system of ruling east and west lines across the paper , lines may drawn parallel to the meridian for adjusting the place of the protractor ...### Other editions - View all

Outline of the Method of Conducting a Trigonometrical Survey, for the ... Edward Charles Frome No preview available - 2016 |

### Common terms and phrases

accuracy accurate Additives adjustment altitude angle apparent applied approximate ascertained axis azimuth barometer base boundaries calculated centre chapter chronometer circle compared construction contained contents contours correction course declination depression described detail determined difference direction distance divisions drawn earth elevation equal error evidently feet figure fixed given gives ground half height horizontal hour inches instrument intersection interval known laid land latitude latter laying length longitude marked mean measured meridian method miles minute nature nearly necessary noon object observed obtained operation parallax parallel plane plotted pole portions position practical proportion quantity reading reference refraction represented roads scale screw sidereal sides sketch spherical star stations supposed surface survey taken taking telescope temperature theodolite thermometer tion traced triangles trigonometrical true vertical zenith distance

### Popular passages

Page 169 - A Solar Day is the interval of time between two successive transits of the sun over the same meridian; and the hour-angle of the sun is called Solar Time.

Page 138 - Ocean, the first thing which strikes us is, that, the north-east and south-east monsoons, which are found the one on the north and the other on the south side of the...

Page 140 - An Account of the Measurement of an Arc of the Meridian, extending from Dunnose, in the Isle of Wight, Latitude 50° 37

Page 114 - When the boiling point at the upper station alone is observed, and for the lower the level of the sea, or the register of a distinct barometer is taken, then the barometric reading had better be converted into feet, by the usual method of subtracting its logarithm from 1-47712 (log. of 30 inches) and multiplying by '0006, as the differences in the column of " barometer " vary more rapidly than those in the ''''feet

Page 73 - BA, the sum of the two refractions ; hence, supposing half that sum to be the true refraction, we have the following rule when the objects are reciprocally depressed. Subtract the sum of the two depressions from the contained arc, and half the remainder is the mean refraction : — If one of the points B, instead of being depressed be elevated, suppose to the point g, the angle of elevation being gA.D, then * " Trigonometrical Survey,

Page 74 - BA, the sum of the two refractions ; the rule for the mean refraction then in this case is, subtract the depression from the sum of the contained arc and the elevation, and half the remainder is the mean refraction -. The...

Page 81 - ... indigo), till it nearly reaches to the necks of the bottles, which are then corked for the convenience of carriage. On setting the stand tolerably level by the eye, these corks are both withdrawn, which must be done carefully, and when the tube is nearly level, or the water will be ejected with violence ; and the surface of the water in the bottles, being necessarily on the same level, gives a horizontal line in whatever direction the tube is turned, by which the vane of a levelling staff is...

Page 181 - Call the zenith distance north or south, according as the zenith is north or south of the object.

Page 114 - Assuming 30'00 inches as the average height of the barometer at the level of the sea (which is however too much), the altitude of the upper station is at once obtained by inspection of Table I, correcting for temperature of the stratum of air traversed by table II.

Page 158 - In the orthographic projection, every point of the hemisphere is referred to its diametral plane or base, by a perpendicular let fall on it, so that the representation of the hemisphere thus mapped on its base, is such as it would actually appear to an eye placed at an infinite distance from it. It is obvious, from the annexed figure, that in this projection only the central portions are represented of their true forms, while all the exterior is more and more distorted and crowded together as we...