TRACT XXVI.

THE

MEAN DENSITY OF THE EARTH.

BEING AN

Account of the calculations made from the survey

AND MEASURES TAKEN AT MOUNT SHICHALLIN*, INORDER TO ASCERTAIN THE MEAN DENSITY OF THE EARTH.IMPROVED FROM THE PHILOSOPHICAL TRANSACTIONS,VOL. 68, FOR THE YEAR 1778.

1 HIS very curious and elaborate paper, contains a fullaccount of all the measurements and calculations, drawn upat the request of the Royal Society, concerning a problem ofthe very first importance in physics, viz, to determine themean density and mass of the, whole body of the earth; andexhibiting the results of the whole, from the very novel modesof computation here employed.

The survey from which these calculations have been made,was taken at and about the hill Shichallin in Perthsldre, inthe years 1774, 1775, and 1776, by the direction, and partlyunder the inspection, of the Rev. Nevii Maskelyne, d. d.f. r. s. and astronomer royal, by whom the manner of mak-ing the survey was pretty fully explained in the PhilosophicalTransactions tor 1775. I have therefore only to give an ac-

* Concerning- this place, (called Thiehallin in the Earse or Gaelic tongue,but pronounced in English Shehallien, and signifying the maiden’s breast), inthe parish of Fortingal, see Sir John Sinclair’s Statistical Account of Scotland.VOL. II.

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