Investigation of the Theory of Isostasy in India |
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1137 Kilometres 14 and footnote A G Topographi Amritsar astronomical Bangalore Bolarum cal Deflection Compensated Colaba 75 compartments computed Continuous Sum F contoured Deesa Deflection cal Deflection Deflection Compensated Residual Deflection Height cal deflection produced DEFLECTIONS AT LATITUDE Dehra Dún depth direction of gravity Earth and Isostasy Everest's Spheroid Bessel-Clarke Everest's Spheroid Residual geodetic latitudes Hayford Height above M. S. L. Height cal Deflection Height Topographical Deflection Himalaya Mountains INDIA BY MAJOR ISOSTASY IN INDIA isostatic compensation considered isostatic equilibrium Italic Jalpaiguri 280 Karachi LATITUDE STATIONS longitude stations MAJOR H. L. CROSTHWAIT maps mean residual MERIDIAN miles miles.-These Name Height Topographi Name Topographi normal to Everest's orographical prime vertical Punnæ RADII OF RINGS REGION Residual Bessel-Clarke Residual Everest's Ring Factor Ring Outer radius Spheroid Bessel-Clarke Spheroid STATION KALIANPUR stratum Sum Continuous Sum Survey of India Topographical Deflection cal Topographical Deflection Height TRIGONOMETRICAL SURVEY uniform isostatic compensation values دو
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Page 4 - ... mean residual + 5 . Region No. 5, NW, mean residual + 4. Region No. 7, W., mean residual — 3 . Region No. 8, E., mean residual — 2. Region No. 9, S., mean residual + 1 . It is seen that the residuals average several times as great in India as in the United States, which leads him to conclude that "Speaking generally it would appear that isostatic conditions are much more nearly realized in America than in India...
Page 2 - The constant 12". 44 depends upon the supposition that for the present purpose the earth may be considered a sphere of which the radius is 6 370 kilometers, or 3 960 miles. The whole of the attracting stratum is assumed to be in the horizon of the station. If the prime vertical component of the deflection at the station is desired, the only change necessary is to measure the angles a' and a, from the prime vertical instead of from the meridian.
Page 2 - ... from the prime vertical instead of from the meridian. If the stratum considered within any compartment be that which is limited below at sea level and above at the actual irregular surface of the earth, then with considerable accuracy the following statement, based upon the formula, may be made: For compartments bounded by circles whose radii are in geometric progression, and by radial lines the sines of whose angles with a reference line are in arithmetic progression, the deflections produced...
Page 2 - ... of certain of the outer circles, as indicated on page 22. (b) To compartments near the station of which the mean surface lies so far above or below the station as to make a slope correction necessary. The method of computing the slope correction is given under the appropriate heading later. (c) To compartments of which some part lies far above or far below the mean elevation for the compartment. This matter will be discussed later in connection with the other errors of computation.
Page 1 - RE Survey of India : Professional Paper No. 10. (1908.) " Investigation of the Theory of Isostasy in India." — Major HL Crosthwait, RE Survey of India : Professional Paper No. 13. (1912.) " On the Origin of the Himalaya Mountains."— Colonel SG Burrard, CSI, RE, FRS Survey of India : Professional Paper No. 12. (1912.) " Notes on the Relationship of the Himalayas to the Indo-Gangetic Plain and the Indian Peninsula."— HH Hayden...
Page 4 - What are here called the residuals are the differences between the deflections computed on the hypothesis of uniform isostatic compensation and the observed deflections A — G, applied to the Bessel-Clarke spheriod.
Page 2 - T (0-25) log« 1 -126 = 0"- 0001000 (h in feet). From this it follows that every hundred feet of stratum above mean sea-level, in any compartment, produces a deflection of 0*-01 at the station.
Page 3 - The stations have been arranged according to regions in the same manner as they are grouped in the Great Trigonometrical Survey of India Vol. XVIII, Astronomical Observations for Latitude, pages (531) to (542).