a paire of compasses

I have some unanswered questions from last week…I’ll get to them, and for now here is one about the compass I use to layout many of my carved patterns.  Mine is quite simple, and fairly stout. That way it doesn’t wiggle at all. I have had some in the past that the shanks, or legs, were too thin & could flex. I sharpen it with a file, just eyeballing the points; might sharpen it twice a year, maybe a little more. It has a fine adjustment screw that I never use, I just use the thumbscrew that pins the leg against the semi-circular piece.  If you are looking to buy old ones, I would say look for those with thicker legs like this one; I have shelved the compasses I have with thin flexible legs.

PF compass

In use, for me it’s a two-hand job. I keep the stationary leg still with one hand, and use the other to swing the arc I need. it might seem fussy to use a compass this way, but I don’t want to strike a line in the wrong spot, the eraser is a plane…

striking an arc

Some of the period sources – Here’s Moxon, with little to say. He does describe its use in a few places, the one I remember best is marking out timber to be sawn.

“Of the Compasses marked E in Plate 5.

aa The Joint, bb the Cheeks of the joint, cc the Shanks dd the Points. Their Office is to describe Circles, and let of Distances from their Rule, or any other Measure, to their Work.”

Then Randle Holme. His first bit sounds pretty familiar:

…a Pair of Compasses, … The Joynt is the place where the Compasses move and turn; The Cheeks of the Joynt is where they go in one to the other; The Shanks, The Points

But when he illustrates them, he describes several kinds. Some tool historians make a big deal out of the distinction between compasses and dividers; I think generally the idea is that those that can be fixed in position are dividers; but note that here Randle H0lme says these dividers “are Compasses which open…” so forth.

Holme's circle dividers

a Pair of Sliding or Circle Dividers, these are Compasses which open upon a Brass semi-circle, and by a small screw is made fast at any station.

Holme screw dividers

a Pair of Screw Dividers, or Pointed…  These are Compasses opened and shut with a screw, so that there is noe danger of their moveing from their station. By all these foresaid Compasses, are described Circles, Ovals, &c, and also Distances are measured and set off from the Rule, or from any other divided Rod or Staffe, to the thing to be wrought upon.

Remember the Stent panel, both workmen depicted there have their own set of compasses, hanging on the wall behind them:

Stent panel

Alexander is always after me about the term “compass.” In the seventeenth century, it’s mostly called “a paire of compasses” – but you do sometimes see it mentioned as “a compass.”

Here are some tools listed in a Bristol, England apprenticeship contract:

1611  Thomas Thomas to Thomas Phelpes Howsecarpenter & Marie:

. . one axe one Addys two Chezilles one Mallet two boorriers one Squire & one Compasse one joynter one foreplane one Rabbett plane on bowltle plane & one Cadgment plane one smoothing plane . .

And a cooper in Salem, Massachusetts, 1654:

George Williams, Salem 

          In Coopers timber 6£-10   3 axes 6s & 3 Coopers axes 12s 

3 frowes 5s  a hatchett & bill 2s  4 addses 15s  8 Drawing knives 10s  2 augers & bung borers 2s  3 pr Compasses 3s  2 Round shaves & an ould Adds 3s  1 handsaw 12d  2 thwart Sawes 10s  3 howells 3s  percer bitts 1s6d  2 Joynters 4s  Trussing hoopes 2s  2 Cresses 2s6d  2 Cressetts 5s  a grindstone 2s  100 hewed staves 5s


10 thoughts on “a paire of compasses

  1. Thank you. I hope you know how much I appreciate your postings. You’re always very detailed, and you back it up with source (primary) material that is stunning.

    I’ve got a thick set that I intend to use to layouts like you do in your video, thanks for all the detail.

  2. Oh, and one other thing I’ve been meaning to ask…

    What is the date/source on the Stent Panel? I want to use it to document some things that are pre-1600 but I don’t know the exact date on it, the clothes make me think it might be, but I’m unsure.


  3. Peter,
    in early 19th century tool catalogs all the tradesmen’s versions are called compasses, with a wing and thumbscrew or without. The more delicate versions for map work, navigation, and drafting are labelled dividers.
    I have no idea why.

  4. Thanks for the information. You answered my question(s). Great article. Really enjoyed the background information and pictures.

  5. I got some shop time last night, and I dug out a pair of dividers/compasses that I picked up at Harbor Freight on a whim, but never used.

    They are very sturdy, solid, and simple. The big turn off for me was the pencil holder, but I discovered it comes off pretty easily by clamping the pencil holder ring in my metal vise, and gently twisting and prying the body of the compass. The cheap weld popped right off, and there was very little of anything left on the compass arm itself.

    The ends were sharpened already on the pair I got, and the locking mechanism worked well. I was able to do some layout last night with it just grabbing a random scrap and playing with it like you show in the picture.

    For those of you who might want to try it out, you can pick up a cheap set here. If you can find a good vintage one, I highly recommend that, but in the mean time here is a more readily available option.

    You can see pictures on my blog post, plus some embarrassing pictures of my first attempts at carving, try not to laugh. :)



  6. Peter,
    Do you have any opinions on the pole setup for the lathe in the Stent panel? I’m musing on there being a counter balance at left and a central pivot. Seems like this might work unless it crashes the counterweight into the ceiling on the down stroke of the treadle. But otherwise, if the annular item at left of the pole is actually the fixing point of a flexible pole, then just what can the construction half-way along the pole be? The pole looks very chunky and therefore mebbe not flexible, but I realise that perspective was a bit flexible around this time!

    • A counter weight system would be much too slow for effective turning. When there is good tension on the pole, it just snaps back very quickly and one can treadle close to twice a second. A weight just would not reverse its direction and fall quickly enough.

    • I’m with Warren, a counterweight is not feasible, nor necessary. I think the bracket-y thing at the back end of the pole is just a fixing point; and the other section is just part of the arrangement that holds the pole up. Mine is quite like this, but not fixed at the rear end…and the loose end does sometimes bang against the ceiling. very rhythmic. I’ll photograph it next week. I never show that part of the lathe here on the blog.

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