Does anyone know how to use an artillery calculating sector?

[cannonmn]

I've had these 3 instruments for a long time and always wondered how they were used.  I found a brief description of one in an Australian museum, but it doesn't give much detail.  You can click on the thumbnails to get larger pix.

http://www.powerhousemuseum.com/collection/database/?irn=53095

[Cat Whisperer]

I see bits an pieces of the scales.

It appears to be similar to the GFT's we used in the Artillary.  (Graphical Firing Table)

If so, each scale would be for a particular round (by weight I assume) and would relate a given charge to distance and elevation.