| 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... | |
| Thomas Keith - 1810 - 482 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... | |
| Thomas Keith - 1826 - 442 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... | |
| 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... | |
| 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,"... | |
| John Gregory - 1843
...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... | |
| 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... | |
| 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... | |
| 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... | |
| 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... | |
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