Page:Popular Astronomy - Airy - 1881.djvu/75

Rh supposition that the earth is spheroidal, it was a



matter of calculation to determine from the geometrical properties of the ellipse, what would be the proportion of the two axes, AA′, BB′, of the earth, which would make the proportions of the curvatures at AB and a b, similar to those determined from the observations. It was inferred that they were in a proportion something like 299 to 300.

Since that time, extensive measures have been taken on other parts of the earth. At the Cape of Good Hope, a measure was made by Lacaille, a Frenchman, in the first instance. At the present time, I am happy to say, that this measure has been repeated and much extended, under the direction of the British Government, by Mr. Maclear, the Astronomer at the Observatory of the Cape of Good Hope. In England, the arc from the Isle of Wight to the Shetland Islands, to which I have several times alluded, has been measured. In India, an arc, extending from Cape Comorin to the neighbourhood of the Himalaya Mountains, has been measured under the direction of the East India Company. In Russia, the measurement of an arc is going on at the present time, extending from the mouth of the Danube to the North Cape. It will form one of the best