Outline of the Method of Conducting a Trigonometrical Survey, for the Formation of Geographical and Topographical Maps and Plans: Military Reconnaissance, Levelling, Etc |
From inside the book
Page 6
This base was measured a second time with prepared deal rods * , and again by a combination of these two methods , the mean of the three valuations being 27404.0137 feet at the level of the sea . The details of the base of verification ...
This base was measured a second time with prepared deal rods * , and again by a combination of these two methods , the mean of the three valuations being 27404.0137 feet at the level of the sea . The details of the base of verification ...
Page 7
Two bars , one of iron and the other of brass , 10 feet long , placed parallel to each other , were riveted together at their centres , it having been previously ascertained , by numerous experiments , that they expanded and contracted ...
Two bars , one of iron and the other of brass , 10 feet long , placed parallel to each other , were riveted together at their centres , it having been previously ascertained , by numerous experiments , that they expanded and contracted ...
Page 8
... out with the greatest precision , with the assistance of sights at each end of the bars ; an average of about 250 feet being completed in one day , and five boxes , giving a length of 52 feet , being levelled and laid together .
... out with the greatest precision , with the assistance of sights at each end of the bars ; an average of about 250 feet being completed in one day , and five boxes , giving a length of 52 feet , being levelled and laid together .
Page 9
... the earth may be considered 21008000 feet ; if , then , the log of the base , in feet , be added to the log of the alti- tude , and the log of the sum of the radius and altitude be sub- tracted therefrom , the remainder will be the ...
... the earth may be considered 21008000 feet ; if , then , the log of the base , in feet , be added to the log of the alti- tude , and the log of the sum of the radius and altitude be sub- tracted therefrom , the remainder will be the ...
Page 16
B On the Ordnance Survey , both of England and Ireland , the largest sized instruments , 3 feet in diameter , were used for fixing the principal stations * . The angles at the vertices of the secondary triangles were observed with the ...
B On the Ordnance Survey , both of England and Ireland , the largest sized instruments , 3 feet in diameter , were used for fixing the principal stations * . The angles at the vertices of the secondary triangles were observed with the ...
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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...
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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...
Bibliographic information
| Title | Outline of the Method of Conducting a Trigonometrical Survey, for the Formation of Geographical and Topographical Maps and Plans: Military Reconnaissance, Levelling, Etc |
| Author | Edward Charles Frome |
| Edition | 2 |
| Publisher | Weale, 1850 |
| Original from | the University of Wisconsin - Madison |
| Digitized | 20 Jul 2007 |
| Length | 253 pages |
| Export Citation | BiBTeX EndNote RefMan |