not 3 meters.
it is about 2.7 meters in the Tang dynasty.

Which source do you use? I have two that contradict each other:

http://zh.wikipedia.org/wiki/%E5%BA%A6%E9%87%8F%E8%A1%A1 (3 meters)

http://www.odts.de/southptr/needham/measures.htm (2.5 meters)

I still wonder how one's supposed to use these things?! I've seen a reprodcution of a muneral of a tang funeral procession and theses...arms... look like flat boards. And if they're shown without the grip, then they sport a mightily short tang for a weapon of that lenght. Comparable japanese arms seemed to have had a grip to blade ratio of almost 1:1.

to yun：
抱歉，请允许我用中文作一下解释，我的英语水平实在还不足以支持我把我要说的东西说明白，而我印象里你的中文水平也没问题……对于古代一尺的长度，事实上我一直也很困扰，因为古代的“尺”这个单位在不同领域定义也不同，简单的划分就有“丈量尺”“营造尺”“裁衣尺”等不同的种类，而我的记忆中唐代武器规格中的一尺大约在25~30公分左右。当然，一来我的印象可能是错的；二来即便同在唐代，一尺也不可能是一个固定值，初唐和晚唐差别就很大。所以陌刀的一丈到底有多长，却实不好说……

BTW：
i think it is a compound bow(长梢弓) on the picture.

Most people think so too. But if it is a bow, why is it unstrung, and why is it so straight when unstrung? That's why Thomas Chen and I first suspected it isn't a bow after all.



There would be no point in carrying it without a grip and with the tang exposed. As the earlier posts on this thread mentioned, that tang-like projection could be a spike at the end of a thick two-handed grip.

I'd use the second source before I used wikipedia. Wikipedia is good to get basic ideas, but terrible when it comes to looking for specific information, and thus Wikipedia will often contradict your other sources.

Case in point: Stephen Colbert did not save the african elephant by trippling it's population.