Unknown Artillery Fuze

[siegfreid]

Can anyone ID this very good looking fuze for me ? It measures 4.626" in length [out of the adapter] with threads of 1.70" . I assume from the marking it may be of US origin . Thank you . Siegfreid.

 

[Alpini]

it's a Waltham mechanical time fuze: http://www.bocn.co.uk/vbforum/threads/54338-Inert-Mech-Time-Fuse