is a popular English<->Latin dictionary. (If you just want to try out the dictionary online, not download it, you can do so here
.) The main reason I don't use it too much is because it doesn't mark vowel length, and I mark vowel length obsessively when I make flash cards out of Latin sentences. But I've gotten tired of consulting a physical copy of Cassell's every time I just want to know which vowels are long, and since Whitaker's Words is
a dictionary, and as far as I can see there is nothing preventing us (from either a legal or technical standpoint) from modifying the dictionary, it seems to me that we ought to try to fix it.
As for the scale of the project, there are approximately 39,000 words in the dictionary according to the website. (It said this of a slightly out-of-date version of the dictionary, but I'm sure the next couple of releases haven't made it significantly larger.) I think, as a group project, adding vowel length for that many entries is within reason, no?
As for where to get the vowel length information from, it should be simple to use the dictionaries that many of us already have. This shouldn't constitute copyright infringement, because a compilation of publicly available information cannot be fully copyrighted. The presentation of the information -- the exact wording and such -- can be copyrighted, but the raw information, such as which vowels are long, cannot.
There is a bit of a problem, however: people don't always agree on which vowels are long. For example, Wheelock and the Oxford Latin Desk Dictionary have "adulēscēns"; Cassell's has "adulescens" with no long vowels. (In fact, Cassell's seems to never mark length on vowels when they are followed by two consonants.) At least one Latin book I've seen -- A&G's New Latin Grammar, available on this site -- says that it's "māgnus", not "magnus", but no other book I've seen has said so, and it's quite old, so maybe general opinion has changed. (Lingua Latina did use "māgnus", in the form "māgnīne", on page 15, line 57, but I assume it was a typo, since it's "magnus" everywhere else.) I'm not fully sure how to resolve this.
Another obstacle is, of course, that humans are not perfect and may make a typo when copying. Thus, some safeguard needs to be implemented, which probably means multiple people doing the same work (so we can spot potential mistakes when two people disagree).
So what do you guys think?