We are working with fairly round stones this weekend at Mackenzie King's Estate just outside Ottawa. Mooreside which is the name of one of the 'cottages' at Kingsmere Farm where Prime Minister King entertained people like Churchill, Yosuf Karsh and Charles Lindberg back in the 40's, has been turned into a lovely tea room now, and happens to be a part of the Gatineau Hills property that has plenty of old dry stone walls on it, most of which are in great need of repair. The 'walls' are mostly long tumbled down piles of rocks. There is enough material there to build with but the trouble is there aren't any flat or squarish stones or any with parallel edges. To rebuild the walls with only these very round-shaped stones requires getting into a special groove. It takes time to get comfortable working with them. It was rough at first but eventually it got smoother.
I have to think of round stones as being square stones without corners. They are not really round at all I tell myself. For one thing they all have some sort of length even though they look roundish. It seems appropriate especially in Ottawa I should 'capitalize' on each stone's length and fit them into the wall, rather than along it. They can be placed so that they lean inwards and so are wanting to slip into the middle of the wall, rather than loosen and fall out of it.
Also when they are placed together in rows they have this lovely quality of forming cradles between each pair of round stones which makes it easier for nestling the next course of round stones into. This actually can add strength to the wall as the stones not only push down but also spread out and tighten up to each other along the wall. There is a kind of dynamic energy running the length of wall, which a wall made with flat stones doesn't have. Building a wall with round stones usually makes it easier to avoid running joints too.
When you use rounded stones in a wall properly the final result is very pleasing to look at and also very structural. When I squint my eyes I can visualize an imaginary grid pattern that has been formed. The stones in the wall look like square stones without any corners.