UPDATED (08 April 2013; 27 May 2019):
Just noticed that that distribution site for Loomis’s books that I originally linked to here is no longer in operation.
The good news, however, is that Loomis’s books have long been available in PDF format via Alex Hays’ Save Loomis! page.
AND they are available via the Internet Archive.
(The books used to be distributed via the Illustration Age site, but that’s no longer the case. The explanation offered is as follows: “Out of respect for the Andrew Loomis estate, Illustration Age has removed these out-of-print books from our free collection.” Previously, however, Illustration Age site claimed that Loomis’s books “are free to distribute because of their public domain status.” My view is, if the books are in the public domain, they’re in the public domain. Too bad for the estate that they didn’t give a shit about the books when they could easily have protected the copyright. But what’s done is done. In fact, the free PDFs are what prompted me and others to buy the lovely the hardcover reprints a few years back. Free e-Loomis for everyone!)