Question: Explain: "I am but mad north-north-west. When the wind is
southerly, I know a hawk from a handsaw."
Answer:Handsaw is probably a corruption for heronsaw, hernsaw.
In some dialects of England harnsa is used, and it is but a
step from this to handsaw. The meaning generally given to
this passage is, that birds generally fly with the wind, and,
when the wind is northerly, the sun dazzles the hunter's eye,
and he is scarcely able to distinguish one bird from another.
If the wind is southerly, the bird flies in that direction, and
his back is to the sun, and he can easily know a hawk from a handsaw. When the wind is north-north-west, which
occurs about ten o'clock in the morning, the hunter's eye, the bird, and the sun, would be in a direct line, and with the
sun thus in his eye he would not at all be able to distinguish
a hawk from a handsaw.
Mertins, Emma. Shakespeare Examinations. Ed. William Taylor Thom, M. A. Boston: Ginn and Co., 1888. Shakespeare Online. 10 Aug. 2010. (date when you accessed the information) < http://www.shakespeare-online.com/plays/hamlet/examq/six.html >.