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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...
Outline of the Method of Conducting a Trigonometrical Survey, for the ... - Page 73
by Edward Charles Frome - 1850 - 253 pages

## An Account of the Operations Carried Out for Accomplishing a ..., Volume 2

William Mudge, Isaac Dalby, Thomas Colby - 1801 - 690 pages
...angles 6AB, aBA, or the sum of the two refractions ; hence, if we suppose half that sum to be the mean refraction, we have the following rule, when the objects...the remainder is the mean refraction. If one of the objects (B) instead of being depressed, is elevated, suppose to the point G, the angle of elevation...

## An Introduction to the Theory and Practice of Plane and Spherical ...

Thomas Keith - 1810 - 478 pages
...( / Bpf + / Asa) = / a sP + / £PS the sum of both the refractions. Hence the following ( Y) RULE. Subtract the sum of the two- depressions from the...arc, and half the remainder is the mean refraction. (Z) If one of the objects (A) instead of being depressed, be elevated, suppose to the point ey the...

## An Introduction to the Theory and Practice of Plain and Spherical ...

Thomas Keith - 1826 - 504 pages
...— (L Asa+ ¿BPÔ) = ¿.asv+ ¿ÔPS the sum of both the refractions. Hence the following (Y) RULE. Subtract the sum of the two depressions from the contained...arc, and half the remainder is the mean refraction. (Z) If one of the objects (A) instead of being depressed, be elevated, suppose to the point e, the...

## An introduction to the theory ... of plane and spherical trigonometry ...

Thomas Keith - 1839 - 498 pages
...L OSP + L OPS) — ( l_ Asa + L ~BPb) =: L c — ( L Asa + L Bpfi). Hence the following (170) RULE. Subtract the sum of the two depressions from the contained...arc, and half the remainder is the mean refraction. (171) If one of the objects (A) instead of being depressed, be elevated, suppose to the point e, the...

## Outline of the Method of Conducting a Trigonometrical Survey, for the ...

Edward Charles Frome - 1840 - 232 pages
...their sum taken from the angle C,f (the contained arc of distance) will leave the angles 6AB, «BA, the sum of the two refractions ; hence, supposing...suppose to the point g, the angle of elevation being gA.D, then * " Trigonometrical Survey," vol. ip 175. See also, on this subject, Woodhouse's " Trigonometry,"...

## Course of Civil Engineering: Comprising Plane Trigonometry, Surveying, and ...

John Gregory - 1843 - 350 pages
...give the refraction. Hence the following rule, when both objects are reciprocally depressed. Deduct the sum of the two depressions from the contained...remainder is the mean 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...

## A Treatise on Surveying and Civil Engineering, Wherein Everything that is ...

P. O'Shaughnessy (Civil engineer) - 1848 - 110 pages
...true refraction. Hence comes the following rule, when both objects are reciprocally depressed. Deduct the sum of the two depressions from the contained...arc, and half the remainder is the mean refraction. But if the point B, be elevated to the point X, instead of being depressed, then the rule is, substract...

## A Treatise on Practical Mensuration

Anthony Nesbit - 1859 - 494 pages
...ASa + Z. BP6) =(Z. OSP + Z. OPS) —(Z.ASa + Z.BPi)=ZC—(Z.ASa + Z.BP6). Hence the following RULE. Subtract the sum of the two depressions from the contained...the remainder is the mean refraction. If one of the objects (A), instead of being depressed, be elevated, suppose to the point e, the Z of elevation being...

## Transactions of the Canadian Society of Civil Engineers, Volumes 3-4

Canadian Society of Civil Engineers - 1890 - 832 pages
...their sum taken from the angle C (the contained arc of distance) will leave the angles b AB and a BA the sum of the two refractions ; hence supposing half...depressed : Subtract the sum of the two depressions rom the contained arc, and half the remainder it the mean refraction. the contained arc and the elivation...

## A Treatise on Practical Mensuration

Anthony Nesbit - 1859 - 482 pages
...ZBPS)-(Z ASa + ZBP6)=(Z OSP + L OPS) - ( L ASa + L BP6)= LC - ( L ASa + L BP4). Hence the following RULE. Subtract the sum of the two depressions from the contained arc, and half the remainder is'the mean refraction. If one of the objects (A), instead of being depressed, be elevated, suppose...