Books Books 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... Outline of the Method of Conducting a Trigonometrical Survey, for the ... - Page 74
by Edward Charles Frome - 1850 - 253 pages ## An Introduction to the Theory and Practice of Plane and Spherical ...

Thomas Keith - 1810 - 420 pages
...these equals take the /»p£,then /cf-/*sA— ZEP£=/»ZSP + /£FS the sum of the two refractions; that is, subtract the depression from the sum of the contained arc and elevation, and half the remainder is the mean refraction. Perhaps it may be necessary to remark, that... ## An Introduction to the Theory and Practice of Plain and Spherical ...

Thomas Keith - 1826 - 442 pages
...the L BP¿, then ¿_ e -f- L esA — L BPÜ>= Z. msp + L OPS the sum of the two refractions ; that is, subtract the depression from the sum of the contained arc and elevation, and half the remainder is the mean refraction. Perhaps it may be accessary to remark, that... ## An introduction to the theory ... of plane and spherical trigonometry ...

Thomas Keith - 1839
...equals take the L BP&, then the sum of the two refractions L msp + L SPS= L c + L esA — L BP£ ; that is, subtract the depression from the sum of the contained arc and elevation, and half the remainder is the mean refraction. Perhaps it may be necessary to remark, that... ## Outline of the Method of Conducting a Trigonometrical Survey, for the ...

Edward Charles Frome - 1840 - 200 pages
...365,110 feet, or 69.15 miles— and one second=101.42 feet. the sum of the two angles, eAB and EBA, will be greater than EAB + EBA (the angle C, or the...station on Allington Knoll, known to be 329 feet above low-water, f the top of the staff on Tenterden steeple was depressed by observation 3' 51", and the... ## Course of Civil Engineering: Comprising Plane Trigonometry, Surveying, and ...

John Gregory - 1843
...refraction. If one of the points, B, be elevated to the point g, instead of being depressed, then the rule is, subtract the depression from the sum of the contained...and half the remainder is the mean refraction. The angles should be taken simultaneously by means of signals, or by watches previously regulated for the... ## A Treatise on Surveying and Civil Engineering, Wherein Everything that is ...

P. O'Shaughnessy (Civil engineer) - 1848 - 98 pages
...if the point B, be elevated to the point X, instead of being depressed, then the rule is, substract the depression from the sum of the contained arc,...and half the remainder is the mean refraction. The angles should be taken at the same time. The amount of refraction found by these rules must be substracted... 