Unknown thingamajig

[Spark plug]

Yes, acquired another unknown measuring device of some sort, but what is it:

 

[Seadog]

These crop up from time to time. I can't recall the name at present, but it's use is for measuring area, I think, on maps.

Planimeter

 

[Shox Dr]

Some sort of trammel for measuring out of round?

 

[scottmk1]

Planimeter I believe its called, for measuring the area of an odd shape

 

[julianthegypsy]

Yep, looks very planimetery to me too!
And a very good one too by the looks of it!

 

[Keith 66]

I have one identical to yours that i acquired a few years ago. A planimeter was often used by naval architects & yacht designers for measuring areas of irregular shapes for example when working out the displacement of a boat, the hull is divided into equally spaced vertical slices across the boat & the areas of each section below the waterline is measured you then use Simpsons rule to multiply the section areas together & the result is the volume of the hull below the waterline. This takes a long time & a lot of sums. I did this at college studying yacht design. Today i just press the design hydrostatics button on Delftship's toolbar & instantly all the calculations are done. In the old days this would have taken a weeks work!

 

[Spark plug]

I have one identical to yours that i acquired a few years ago. A planimeter was often used by naval architects & yacht designers for measuring areas of irregular shapes for example when working out the displacement of a boat, the hull is divided into equally spaced vertical slices across the boat & the areas of each section below the waterline is measured you then use Simpsons rule to multiply the section areas together & the result is the volume of the hull below the waterline. This takes a long time & a lot of sums. I did this at college studying yacht design. Today i just press the design hydrostatics button on Delftship's toolbar & instantly all the calculations are done. In the old days this would have taken a weeks work!

Very good description.

Looks to be a quality instrument, but something I would never use.

 

[RonA]

Another vote for planimeter.
In my early student apprentice days, we employed a lot of Kent flow chart recorders. Every now & then we used a planimeter on the charts to confirm the accuracy of the mechanical totalisers
RonA