The last two replies on this genealogy forum pretty much answer the
question...of both 'stillard'...and the use in 'pairs'...so I would
venture to say (altho knowing Nothing about this subject/these
items)...that 'pair of shillards' is a misspelling (possibly
transcription of poor handwriting where the 't' looked like an 'h'?) of
stillard...the scales.  Perhaps like the word pants...it is
plural...since there are more than one part to them. ?  We use "pair of
pants"...so maybe it's the same sort of thing. ??

http://archiver.rootsweb.com/th/read/BRETHREN/1999-04/0923614605

Here's a similar estate inventory...with "1 pair stillard"...listed.
http://freepages.genealogy.rootsweb.com/~paday/dobbers/russel_barwick.ht
ml

>-----Original Message-----
>From: Marty Pickands [mailto:[log in to unmask]] 
>Sent: Wednesday, August 17, 2005 2:41 PM
>To: [log in to unmask]
>Subject: Re: mystery object: "Pair of Shillards"
>
>
>If the etymology "steelyard"-"stillard"-"shillard" is correct, 
>as seems plausible, why are they invariably called a "pair?" 
>Although one could say it is because of the two hooks, "yard" 
>seems to refer to the beam itself, of which, on most examples 
>I have seen pictured, there is only one. Perhaps we should 
>look at old roots sounding like "shill." There seem to me to 
>be at least three meanings associated with this root: the 
>common one, meaning a false bidder in a negotiation, a second 
>one meaning the opposite of "shall" (as in "shill he-shall 
>he") and one from which the root of "shilling" is derived. 
>Significantly, this last is said by the Free Dictionary online 
>to have likely originated with the old Scandinavian term, 
>"skilling," meaning "marks on a stick." This suggests that the 
>word, like "scales," probably derives from a term referring to 
>the interval marks on a balance beam, and the shilling, like 
>the pound, was originally defined by its weight. While this 
>supports the idea that "shillard" refers to a stillyard, it 
>still does not explain the use of the word "pair" to describe 
>it. Any suggestions on that?
>
>Marty Pickands
>