In one of the earliest poems about curling, by the Lanarkshire poet, James Graeme, and first published in 1773, we find:
The goals are marked out; the centre each
Of a large random circle; distance scores
Are drawn between, the dread of weakly arms.
In Thoughts on the Seasons, (1789), David Davidson the Kirkcudbrightshire poet wrote, when describing the play at a bonspiel between Glenbuck and Bentudor:
Then Fotheringhaw, a sidelin shot,
Close to the circle played.
And in the next year Alexander Wilson wrote:
To the ice of Loch Tankard, our buirdly braw callans
First bare the big whin-stane, and marked out the tee;
Syne drew down the dread hog-score, the hack and the circle,
Around which our Fathers oft sported wi’ glee.
The first badge or medal of the Duddingston Curling Society, which was struck in 1802 “to distinguish the members from any other gentleman” shows a circle inscribed in the ice of the loch.
The Rev. John Ramsay in his An Account of the Game of Curling, by a Member of the Duddingston Curling Society, 1811, page 4 states: "The place for the rink being chosen, a mark is made at each end, called a tee, toesee, or witter. It is a small hole made in the ice, round which two circles of different diameters are drawn, that the relative distances of the stones from the tee may be calculated at sight, as actual measurement is not permitted till the playing at each end be finished. These circles, in the technical language of the game, are called broughs."
Sir Alexander Boswell sang the following song to the Duddingston curlers at a dinner in McEwan’s Tavern on 11 December 1816:
"Soop the rink, lads, wide enough;
The hogscore mak’, and mak’ ilk brough;" (make every circle.)
The curlers of the eighteenth and beginning of the nineteenth centuries clearly played their stones into a circle round the tee.
It is therefore a bit surprising that in the Annual for 1838-9 in which the first rules of the Grand Caledonian Curling Club were published there was no explicit provision in the Rules of the Game for circles, or broughs, or a house.
Rule 16th stated: “No measuring of shots allowable previous to the termination of the end.”
When rules were first promulgated for district medals for points in the Annual for 1839-40 it was provided “3d, A circle eight feet in diameter shall be drawn round the tee…” and the circle was an important part of the scoring system, for one point, drawing, demanded that a stone be put into the circle and others demanded that a stone be struck out of it.
The 6th rule in the Annual for 1840-1 was: "...In cases in which each party has a stone equally near the tee, neither to be counted, and the winning party of the previous end is again to fill the ice. Measurements to be taken from the centre of the tee to that part of the stone which is nearest it."
In that for 1841-2 in Rule 6 we find this addition to the rule, printed in italics: “No stone to be counted which does not lie within seven feet from the tee, unless it be previously otherwise agreed upon.”
After the first thorough revision of the rules, which contained 'great improvements' according to the editor, we find in the Annual for 1854-5: “Rule 1….A circle of seven feet radius, to be described from each Tee as a centre, and no stone to count which is wholly without this circle…”
The revised Rules clarified when a stone was in or out of the circle. “10…No stone shall be considered within or without a circle unless it clear it; and every stone shall be held as resting on a line, which does not completely clear it; - in every case, this is to be determined by placing a square on the ice, at that part of the circle or line in dispute.” This was the first mention of a circle but it must have been part of the game from its beginning.
The new Rules were accompanied by a “Diagram or Plan” called “The Rink”, which set out a number of dimensions including those of smaller circles within the seven foot, of 2 and 4 feet in diameter, which were not obligatory.
The seven foot rule lasted until the AGM of 27 July 1938, when after much discussion involving the fact that in Canada they had been playing for years with a six foot circle in contravention of the Rules of the mother club, a compromise was reached. Rule 47 now read: “The Tees shall be 38 yards apart – and, with the Tees as centres, Circles having a radius of not less than 6 feet nor more than 7 feet shall be drawn. Additional inner Circles may be drawn.”
On 24 July 1963 the rule was changed to 6 feet, since all the other curling associations in the world, as well as all the Scottish ice rinks, used that measure.
The only change from that to the present is the decimalisation of the imperial measurements, which took place at the revision of 1980. The present rule is: “Section A.
3. The tees shall be 34.75m. (114 feet) apart and, with the tees as centres, circles having radii of 1.22m. (4 feet) and 1.83m. (6 feet) shall be drawn. Additional inner circles may also be drawn. ..”