How to read a Boley gauge?

[Lopyswine]

hey everyone,
we have a pedo exam tomorrow. Our teacher said he might be evil and put a question on the exam about reading a Boley gauge. He gave us a few slides but I can't figure it out.

Can someone point me to a tutorial or ppt? Or I can email someone the slides and maybe they could interpret them for me....

thanks!

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[ODEP PEDO]

Boley gauge is an instrument used for measuring in the metric system. A Boley gauge is accurate to tenths of millimeters. Used in Pedo mostly for space analysis, some would suggest to use it for band selection even.

 

[ODEP PEDO]

Meant to write Boley, sorry for the typo on the title

 

[Lopyswine]

I get the purpose and function of the Boley gauge, however I can't read it.

How do you read the gauge?

 

[KOM]

So you know you've got a fixed scale and a sliding scale.

You begin by looking at the fixed scale where the bold face numbers are in cm (therefore the 1 and 2 on the fixed scale represent 10mm and 20mm respectively.)

The zero mark is the first tick mark on the sliding scale. The zero mark determines the whole mm amount depending on where it is located in relation to the fixed scale. (Ex- if it's between the 11 and 12mm notch on the fixed scale it's 11mm. If it's between 12 and 13mm the whole mm amount is 12mm).

Then, you look along the sliding scale and find which tick mark on the sliding scale most closely lines up with a tick mark on the fixed scale. That tick mark is going to represent your tenths of a mm. Just remember the zero tick mark on the sliding scale doesn't count as 1. Hope that helps.

 

[blue34]

You probably already had your test... hope it went well!
Here is an online tool that helped me figure out how to read a Boley gauge. Its a Vernier Caliper in the example, but its pretty much the same concept:
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=52