A box as in with a top also?  It is a cube or more like a tiny square cup? 
Glazed inside?  Glazed on the exterior sides?
Reminds me of the cup from an artist's paint set.
I've had very similar looking little things with W N or W&N for Winsor & 
Newton "Water Color in Cakes".  They came in "Whole Cakes" and "Half Cakes" 
and some were empty so they could be filled by the artist.

Your Registration Number dates from sometime between January 1886 to January 
1887.

S. Walter

-----Original Message----- 
From: Krista Eggleston
Sent: Saturday, December 13, 2014 9:39 AM
To: [log in to unmask]
Subject: Mystery Object

This is a square ceramic 'box' that is 2 cm by 2 cm on the surface and about 
1cm X 2cm on the sides. It was found in Detroit at a site dating back to the 
early 1900s. On the surface are the letters 'R&S' underneath is 'Rd No 
47843'. We believed it may be a component to something electrical in nature 
but have been unable to find anything it would belong to. Link to the photo 
is below:

http://i1382.photobucket.com/albums/ah242/kristaeggleston/Yeoldcomputerkeyinfield_zpsc9f5c592.jpg

Thanks in advance for the help!