## An Account of the Calculations Made from the Survey and the Measures Taken at Schehallien in Order to Ascertain the Mean Density of the Earth: By Charles Hutton, ... Read at the Royal Society, May 21, 1778 |

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### Common terms and phrases

12 Radii affirmative altitude or depression angle formed angle of elevation Astronomer Royal attraction axis Bearings at h Bearings atF brass standard Calculations to ascertain chain circles common difference corresponding degree of accuracy degrees and minutes Diff Diff.of Diff.of Alt difference of altitude Diss distance DtOp Pole elevation or depression equal fame line feet ground hill horizontal angles hutton's Calculations inches length logarithms lumn manner matter mean density measure measuring rods meridian method N.E. quarter nearly Northern number of small observed perpendicular pillars plane points Pole 6 ft proper quadrant radius ratio relative altitudes Rings rods S E C T I Schehallien second column SECT SECT1ON section line shew sines South Southern observatory spaces stations subtracted Sum of Dep survey taken tangents Theodolite theorem thermometer tical tion toises vacuities Vert vertical angles whole earth z.'s Bearings

### Popular passages

Page 94 - S$llf, that is, as 9933 to 1, very nearly, on supposition that the density of the matter in the hill, is equal to the mean density of that in the whole earth.

Page 94 - ... seconds. Hence, then, it is to be inferred, that the attraction of the earth is actually to the sum of the attractions of the hill nearly as radius to the tangent of...

Page 97 - ... toward the more central parts, great quantities of metals, or such like dense matter, to counterbalance the lighter materials, and produce such a considerable mean density on the whole. If we suppose, for instance, the density of metal...

Page 94 - ... seconds, that is, as 1 to .000056239, or as 17781 to 1 ; or as 17804 to 1 nearly, after allowing for the centrifugal force arising from the rotation of the earth about its axis. Having now obtained the two results, namely, that which arises from the actual observations, and that belonging to the computation, on the supposition of an equal density in the two bodies, the two proportions compared must give the ratio of their densities, which...

Page 92 - THE effect of the attraction at the northern observatory was to that at the southern one nearly as 70 is to 89, or as, 7 to 9 nearly. This difference is to be attributed chiefly to the effect of the hills on the south of the southern observatory, which were considerably greater and nearer to it than those on the back of the northern observatory.

Page 1 - ... mean denfity. He then goes on, having the ratio of the mean denfity of the earth to that of water, and the relative denfities of the planets one to another, determined from phyfical confiderations, to find their denfities relative to rain water, which he makes as follows : Water — i Mars — 3 \ The Sun •— IT\ Moon — 3T'T Mercury — 9^ Jupiter — i...

Page 94 - If, that is, as 9933 to 1 very nearly, on supposition that the density of the matter in the hill is equal to the mean density of that in the whole earth. But the Astronomer Royal found, by his observations, that the sum of the deviations of the...

Page 97 - ... of this wonderful man ! Since then the mean density of the whole earth is about double that of the general matter near the surface, and within our reach, it follows, that there must be somewhere within the earth, toward the more central parts, great quantities of metals, or such like dense matter, to counterbalance the lighter materials, and produce such a considerable mean density on the whole. If we suppose, for instance...

Page 62 - ... of as many vertical columns, or pillars of matter, into which the hill, and the adjacent ground, may be supposed to be divided, by vertical planes, forming an imaginary group of vertical columns...