Here is an old cast iron door latch with a spring and pull chain.  The body of the lock measures 

5 1/4" by 2 1/4".  The spring / pull chain work easily.  This Eastlake pattern is from the 1870's to 1880's.  It does not come with 

a metal receiver end.  This latch has been refurbished by being buffed for rust and clear-coated - ready to install.

Careful packaging.