Thread: Mystery Piece

I recall my dad having one of these when I was a very small child. He told me it was a ruler. I could never understand how a cylindrical rod could work to rule straight lines.

EDIT: Since posting, I googled antique cylindrical rulers and sure enough, it's a 19th century ruler.

mick

I had a modern day rolling ruler, made of plastic. It has a plastic cylindrical roller equivalent to that shown, but set into a flat ruler that was graduated. While the graduated ruler could be used as a basic ruler, the main use of the unit was for transferring a line to a new position parallel to the original by aligning with the original then rolling across the surface to the new position.

I believe the unit illustrated could be used in the same way to transfer lines, possibly in conjunction with a regular flat ruler being slid against the rolling ruler to use as an edge to draw the line.

Originally Posted by Glider

I recall my dad having one of these when I was a very small child. He told me it was a ruler. I could never understand how a cylindrical rod could work to rule straight lines.

EDIT: Since posting, I googled antique cylindrical rulers and sure enough, it's a 19th century ruler.

mick

Thanks Mick, I think you're pretty well right on the money there. I'm going to have to think long and hard before I go cutting it up now.

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Originally Posted by malb

I had a modern day rolling ruler, made of plastic. It has a plastic cylindrical roller equivalent to that shown, but set into a flat ruler that was graduated. While the graduated ruler could be used as a basic ruler, the main use of the unit was for transferring a line to a new position parallel to the original by aligning with the original then rolling across the surface to the new position.

I believe the unit illustrated could be used in the same way to transfer lines, possibly in conjunction with a regular flat ruler being slid against the rolling ruler to use as an edge to draw the line.

I have the brass version of your plastic rolling or "parallel" rule. Lives on my desk at work. Most of the time it's used to see if the junior engineers and drafties have any imagination.

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How else would you get a straight, unsmugged line with an ink nib or a quill?

My rolling rulers have a pair of serrated wheels, or rubberised rollers, I'd imagine it would be pretty darn tricky using a rolling rod and not going off angle at either end while using it!