You might want to look at this :http://www.traphof.org/Equipment-Artifacts/history-of-glass-target-balls.html
 
> Date: Mon, 4 Oct 2010 17:44:22 -0400
> From: [log in to unmask]
> Subject: Mystery Glass Vessel
> To: [log in to unmask]
> 
> Dear Histarch-ers,
> 
> More from the Fairbanks House in Dedham, MA -- thanks to everyone who helped
> out with our pewter button a couple of weeks back. We've got another
> mystery: a small, globular brown glass vessel of some sort. The vessel (or
> should I say *vessels* -- we've found close to 60 based on individual necks
> recovered!) roughly resembles a Christmas ball ornament, although not quite
> as thin. They have distinct mold marks and many of the necks show signs of
> melting, some beyond what could still be considered functional. This
> deformation has led us to speculate that they might have been some sort of
> replaceable oil lamp globe. I've posted pictures of a base and a neck, as
> well as a rather lame attempt to illustrate their original shape, at our dig
> blog:
> http://fairbanksarchaeology.blogspot.com/2010/10/mystery-glass-vessel.html.
> 
> These vessels come from a context that has been initially dated to sometime
> after the mid 19th century, possibly as late as the early to mid 20th
> century. If anyone can confirm our oil lamp hypothesis or point us in
> another direction, that'd be greatly appreciated! Thanks in advance~
> 
> Best,
> Travis Parno
> 
> 
> -- 
> -----------------------
> Travis G Parno
> 
> Doctoral Candidate
> Boston University
> Department of Archaeology