Unusual Gauge Tool ??

[Danks]

Help is needed to Identify this Tool, it appears to be some sort of Gauge/size tool, of unknown use.  The tool came from a Railways workshop in South Australia. The markings on the handle are:-
Whitworth, Manchester, 2.1/16" to 2.15/16", There is what could be a crest/badge but it is very faint and indistinct. The 8 steps are each marked in the odd fractional increments  from 2.1/16 through to 2.15/16

[leg17]

Could be a caliper gage.

[lptools]

A go-no-go gauge?

[JohnD]

Joseph Whitworth Co. in Manchester England was famous for precision tooling and machines and of course "Whitworth Threads". I'll try attaching a link to an interesting read on the "Whitworth Society". He was apparently the first to make a ruler calibrated down to 1/32" and was ridiculed in his day for proposing that precision work be measured to such an unreasonably small increment.

My question on this tool--- carefully check it with a micrometer--- Do the different diameters correspond exactly (within .001" or so) of the diameters marked on them? If so-- it may have been a simple plug gauge to give quick measurement of common hole sizes. Except I don't understand why the common even sizes would be omitted?

If the stamped sizes DON'T correspond to the steps--- it may have been something used to determine the next larger shaft or reamer size that would be required to fit & machine a worn hole or bushing. In any case it's a collectible machinist tool.
http://www.whitworthsociety.org/history.php?page=2

[leg17]

Normal calipers were used to compare a workpiece to a known standard.  Not so much today with affordable micrometers available.
In this case, I expect this to be a caliper gage to fill in the 'in between' sizes already commonly found.
The workpiece is not checked directly with this gage, but it serves much like modern gage blocks do to establish a standard.
(The advent of inexpensive asian gage blocks have fostered an entire generation of improper gage block use, but in a 'time is money' environment, they have almost become, of all things, perishable tooling!  Our forebears in the shop would be horrified at the abuse gage blocks see today.  But that is different rant for another day.)

As suggested above, check to see if the sizes are actually what is marked on the gage.

[turnnut]

 ?? to check wear in bored out holes ???  various parts  on a train ???

[toolman]

I agree with Iptools, in that it is a quick check, inside diameter, reference gage, for a hollow cylinder.

[Danks]

 Hi Folks, I have had the steps measured (as i do not have the means to accurately make that size measurements), and have been informed that each of the marked steps is within .001"(or so) of the marked size.