Scrimshaw, wood inlay, compass point or sextant?

[talesofthesevenseas]

I can't find one exactly like this device, but this is the general idea, to help with the visual on roof pitch:

[fancypants]

Don't think it's for roof .

Hey ... howsa bout a gunners quadrant ?

[waywardangler]

While this whole object's use is a mystery, doesn't it look like there are some intials incorporated in the engraving?  There is a tulip, a flower, and what looks like 2 letters.  Possibly a T or P and an S?

[Skinny]

While this whole object's use is a mystery, doesn't it look like there are some intials incorporated in the engraving?  There is a tulip, a flower, and what looks like 2 letters.  Possibly a T or P and an S?

I noticed that also. Looks like a T and an S.

[cogar]

I think I know what this is. It's a carpenters tool used in framing wood roofs. The reason the numbers on the curved part don't make sense is they aren't degrees. The are numbers used to mark or measure roof pitch. Pitch is measured in inches of rise in 12 inches of horizontal run.

Syl, only if cutting roof rafters for doll houses, it is only 3 1/2" on each side arm.


I think the "dots" in the squares of the arc are just decorations.

And I agree with Skinny, it does open to 90 degrees, see pic pelow.

One has to be careful looking at the picures, especially the ones with the tape measure because of the angle to vertical the pictures were taken and/or the per say parallax.

I think I got it, I think I got it. …… It’s 16th Century French. See below and the pic w/ruler.

The map scale that was used for these maps then was in the old units of measurement:

1 ligne=100 toise.

One toise (English fathom) was equal to 6 pieds (English feet), one pied (English foot) was equal to 12 pouces (English inches), and one pouce was equal to 12 lignes (English lines). So one ligne (1/12 of an inch) on the map was equal to 100 fathoms (600 feet) on the ground...thus a modern scale, or more properly, the repesentative fraction, of these maps is 1:86,400 (or 1 : 6x12x12x100).   http://www.informatics.org/france/maps.html

[talesofthesevenseas]

Hold on a sec gang, remember that architectural DRAFTSMEN have to draw out the roof pitch, and also remember that it is not at all necessary for a pitch guage to be large, just because the roof is. The proportions have nothing to do with it, it is all about determining the angle. Typically a drafter draws a horizontal line (the run) with 12 units of measure and a varying vertical measure (the rise) and then you draw a line from the end of one to the end of the other, and that's your angle. But this little gadget would make it SO easy! It makes perfect sense and if you were a carpenter you could carry this with you and check the angle as you were building. I think Syl's got the right idea. I really hope that this one goes to a museum or other authority to get checked out so that we can learn what it's true use was!  VERY interesting topic this has been!

[KC]

You have a truly wonderful piece of history there!

I would bet that 1) You had a drafting/surveying engineer/designer in the family (I don't think this fine piece would have been used by an everyday craftsman no matter the era) 2) it is worth $$$$$$$$$$

AND IT LOOKS FRENCH!!!!!!!!!!!!!!!!!!!!!!!

[waywardangler]

I believe the dots in the arc are eigth divisions, the squares or small boxes are fourth divisions and the longer line in the center is a half.  What it measures is the BIG question.  I can't fathom what cogar is talking about because after looking at all this my eyes are pied, and my feet are asleep.  I have to go lay on the ground and stretch my inches out fully to scale.

I hope ppgs takes this someplace informative (like a museum) and someone can tell us what it is and what it really does.

[KC]

waywardangler...LOL OLOL!

[cogar]

Tales, ....... Syl stated and I agree that "Pitch is measured in inches of rise in 12 inches of horizontal run", ....... but the horizontal "scale" on that "thingy" is not in inches.

The circular “scale” consists of 12 large segments per 90 degrees of arc, …. with one (1) ½ segment mark and three (3) ¼ segment marks, …. (and if Wayward is right about the "dots" in the squares, ….  seven (7) 1/8 segment marks) …. per each one of the 12 segments or per ¼ of a circle. That means a full circle would equal either 192 or (including the dots) 384 increments.

Which doesn’t make a lot of sense for a 360 degree circle.

[Skinny]

My first instinct was "architect". An affluent professional could afford a fancy tool like this. Cougar, I'm glad you agree that it's sixteenth century. I felt like I was kind of going out on a limb with that one.

[talesofthesevenseas]

Pitch can be calculated in any unit of measure. You can have 12 lengths of your nose horizontally, and 6 lengths of your nose vertically, and the angle will be the same as if you drew it in inches. Architectural drawings are scale drawings and what scale they are drawn in differs from drawing to drawing. Usually the roof pitch appears as a simple triangular diagram off to the side of the drawing like this:


On the curved part of the tool, you are not PRODUCING the angle, but you are READING it, just like you would read it off a screen, just like you would if it was a digital read out. It's quite an ingenious and deceptively simple little device.

I was a drafter for 18 years and taught vocational drafting school for 9 of them. I think Syl got it right. The way to find out for sure would be to draw out roof pitch triangles to scale at 1/12, 2/12, 3/12 etc. roof pitch, and see if when you set the device to READ OUT 1, 2, 3 along the curve, if the straight edges match the roof pitch diagrams. If they do, that's got to be it. I'm putting my money on Syl this time.

[talesofthesevenseas]

When I get home tonight, I'm going to draw out a scale drawing like this device to show what I mean in the above post. I think that will make it a little clearer.

[talesofthesevenseas]

I did a sketch to show you what I mean. I really think Syl is right, that this is roof pitch. You would use the device like this:

[talesofthesevenseas]

Zoom up on the photo I posted above so that you can see the numbers on the curve. Read the number on the curve at the point where the angle that changes crosses the curve. Look at the houses below each setting to see how the angle on the device, transfers to an actual roof. See what I mean?