_The Observatory in Arizona._

In 1894, after a careful search for the best atmospheric conditions, Mr.
Lowell established his observatory near the town of Flagstaff in
Arizona, in a very dry and uniform climate, and at an elevation of 7300
feet above the sea. He then possessed a fine equatorial telescope of 18
inches aperture and 26 feet focal length, besides two smaller ones, all
of the best quality. To these he added in 1896 a telescope with 24 inch
object glass, the last work of the celebrated firm of Alvan Clark &
Sons, with which he has made his later discoveries. He thus became
perhaps more favourably situated than any astronomer in the northern
hemisphere, and during the last twelve years has made a specialty of the
study of Mars, besides doing much valuable astronomical work on other
planets.

_Mr, Lowell's recent Books upon Mars._

In 1905 Mr. Lowell published an illustrated volume giving a full account
of his observations of Mars from 1894 to 1903, chiefly for the use of
astronomers; and he has now given us a popular volume summarising the
whole of his work on the planet, and published both in America and
England by the Macmillan Company. This very interesting volume is fully
illustrated with twenty plates, four of them coloured, and more than
forty figures in the text, showing the great variety of details from
which the larger general maps have been constructed.

_Non-natural Features of Mars._

But what renders this work especially interesting to all intelligent