And this may be seen, as I saw it, by any one going up Monbroso
[Footnote: I have vainly enquired of every available authority for a
solution of the mystery as to what mountain is intended by the name
Monboso (Comp. Vol. I Nos. 300 and 301). It seems most obvious to
refer it to Monte Rosa. ROSA derived from the Keltic ROS which
survives in Breton and in Gaelic, meaning, in its first sense, a
mountain spur, but which also--like HORN--means a very high peak;
thus Monte Rosa would mean literally the High Peak.], a peak of the
Alps which divide France from Italy. The base of this mountain gives
birth to the 4 rivers which flow in four different directions
through the whole of Europe. And no mountain has its base at so
great a height as this, which lifts itself above almost all the
clouds; and snow seldom falls there, but only hail in the summer,
when the clouds are highest. And this hail lies [unmelted] there, so
that if it were not for the absorption of the rising and falling
clouds, which does not happen more than twice in an age, an enormous
mass of ice would be piled up there by the layers of hail, and in
the middle of July I found it very considerable; and I saw the sky
above me quite dark, and the sun as it fell on the mountain was far
brighter here than in the plains below, because a smaller extent of
atmosphere lay between the summit of the mountain and the sun.
[Footnote 6: _in una eta._ This is perhaps a slip of the pen on
Leonardo's part and should be read _estate_ (summer).]

Leic. 9b]