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
Results 6-10 of 41
Page 17
... latter . The length of the sides of the smallest triangles must depend upon the intended method of filling up the interior . If the contents within the boundaries of parishes , estates , & c . , are to be calculated , the distances ...
... latter . The length of the sides of the smallest triangles must depend upon the intended method of filling up the interior . If the contents within the boundaries of parishes , estates , & c . , are to be calculated , the distances ...
Page 21
... latter method is by far the most expeditious . In the " Base du Système Métrique , " the sides of the triangles were computed by all three methods . On the Ordnance Survey they were formerly mostly calculated by the second , and checked ...
... latter method is by far the most expeditious . In the " Base du Système Métrique , " the sides of the triangles were computed by all three methods . On the Ordnance Survey they were formerly mostly calculated by the second , and checked ...
Page 22
... latter method is generally now practised on the Ordnance Survey . An instrument of the same size has since been made by Messrs . Troughton and Simms for the survey of India , as also another for the Ordnance Survey . A theodolite of 18 ...
... latter method is generally now practised on the Ordnance Survey . An instrument of the same size has since been made by Messrs . Troughton and Simms for the survey of India , as also another for the Ordnance Survey . A theodolite of 18 ...
Page 23
... latter of which is to be preferred on account of its not being affected by the humidity of the atmosphere . The following simple and ingenious mode of fixing these cobwebs , which to a novice is often a difficult and tedious operation ...
... latter of which is to be preferred on account of its not being affected by the humidity of the atmosphere . The following simple and ingenious mode of fixing these cobwebs , which to a novice is often a difficult and tedious operation ...
Page 42
... latter method is sup- posed to assist in the plotting ; but if references to the starting points of the different lines , and their junctions with each other , are entered in the field - book kept according to the first system , and the ...
... latter method is sup- posed to assist in the plotting ; but if references to the starting points of the different lines , and their junctions with each other , are entered in the field - book kept according to the first system , and the ...
Contents
1 | |
13 | |
30 | |
56 | |
70 | |
100 | |
115 | |
118 | |
234 | |
235 | |
236 | |
237 | |
238 | |
239 | |
240 | |
241 | |
138 | |
162 | |
173 | |
180 | |
189 | |
195 | |
215 | |
230 | |
231 | |
242 | |
243 | |
244 | |
245 | |
246 | |
247 | |
248 | |
252 | |
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 acres adjustment angles of elevation Apparent altitude ascertained astronomical axis azimuth barometer base boundaries calculated centre chain chronometer circle computed contour lines correction course curvature declination degree depression determined difference of longitude direction divisions earth equal feet field-book fixed Géodesie given Greenwich Greenwich mean ground height horizontal line hour angle inches index error instrument intersection interval laid latitude length lunar distance marked mean solar measured meridian method miles Nautical Almanac necessary noon object observed angles obtained Ordnance Survey parallax parallel pickets place of observation plane plotted pole portions position purpose radius reading reference refraction right ascension roads rods scale screw sections semidiameter sextant sidereal sides sketch slopes spherical spherical excess spirit level star stations subtractive surface taken tangent telescope temperature theodolite thermometer tion traced triangles trigonometrical points Trigonometrical Survey tube vane vertical zenith distance
Popular passages
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 73 - AB, aBA, 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 g AD, 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 112 - ... diameter. B, a sliding tube of tin, moving up and down in the pot ; the head of the tube is closed, but has a slit in it, C, to admit of the thermometer passing through a collar of cork, which shuts up the slit where the thermometer is placed. D, thermometer, with so much of the scale left out as may be desirable. E, holes for the escape of steam. The pot is filled four or five inches with pure water ; the thermometer fitted into the aperture in the lid of the sliding tube, by means of a collar...
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...
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 14 - heliotrope," which is a piece of looking-glass, so adjusted as to reflect the sun directly to any desired point, is the most perfect arrangement. For night signals, an Argand lamp is used ; or, best of all, Drummond's light, produced by a stream of oxygen gas directed through a flame of alcohol upon a ball of lime. Its distinctness is exceedingly increased by a parabolic reflector behind it, or a lens in front of it. Such a light was brilliantly visible at 66 miles distance. (385) Observations of...