lasico planimeter

Hi,

Measure a room in your house/office you know the dimensions of. Work out what unit the answer is in based on the answer you already know.

I have not dealt with Ft and Ins for many years, I seem to recall that there would be 144 sq ins in a foot so an area 5 ft X 2 ft would be 10 sq ft, or 1440 sq ins. The same as if you had used inches all the way and multiplied 60 X 24.

My planimeter has not been out of it's box in many years however try the following

Draw a series of squares of know sizes and begin with the planimeter measuring them, you will undoubtedly notice that there will be variations in your readings. This is normal and with a little practice you will get better.

I expect you have an imperial planimeter so when you measure 1 sq inch your reading should be 1.00 this is factor N, when measuring on a drawing this is to scale and it is no longer 1 square inch.

If your drawing is 3/4" = 1' the N factor of 1.00 is now 256 sq inches or 1.778 sq ft

Hope this helps

G

A tip I remember from Kinney's book on yacht design: trace around the shape you're measuring in both directions and average the readings.

Francis Kinney recommends averaging several readings but I do not believe that he measures in both directions. Most plain meters only work clockwise

It has been a long time since I read my Kinney book, so it's possible I've got it wrong. It stuck in my mind because I first read (but didn't understand a lot of) the book when I was a kid and it wasn't until much later that I had a chance to try a planimeter and I dug out the book and that's what I think it said, but at this point it's a memory of a memory, so it could be wrong.