Hats in Art History

The Village Hat Shop has a nice selection of images of hats in Western art.

Google Hats

There are a remarkable number of works on hats available through Google Books, some with just the bibliographic information but many full text, out of print works too.

To Hat

The indispensable Oxford English Dictionary reveals the history of Hat as a verb:

a. trans. To cover with a hat; to furnish or provide with a hat. Also, to bestow the cardinal's hat upon.
c1430 Pilgr. Lyf Manhode II. cxxii. (1869) 121 Al be it I be mantelled and wel hatted. 1598 FLORIO, Incapellare..to hat one. 1852 W. JERDAN Autobiog. II. xiii. 164 We had..hatted and cloaked ourselves. 1885 Boston (Mass.) Jrnl. 31 July 1/6 The Pope..held a public consistory..at which the newly appointed Cardinals were hatted. 1891 A. THOMAS That Affair I. x. 171 Miss Polthuan hats and veils herself.

b. To place one's hat on (a seat) so as to claim it.
1886 Philad. Times 10 Apr. (Cent.), Twenty seats had..been hatted before noon to secure them for the debate.

c. intr. To work alone. (Cf. HATTER n. 2.) Austral.
1891 Age 25 Nov. 6/7 (Morris), Two old miners have been..hatting for gold amongst the old alluvial gullies. 1900 H. LAWSON On Track 88 And he ‘hatted’ and brooded over it till he went ratty. ref