Anne â€” I am fairly certain that you have miscounted. Or, to put it another way, I think you counted the one with your finger on twice!
If you think about it, cutting tools and turntables were marked out in degrees; some perhaps with a lock that would only engage at a whole degree. Therefore you will find that virtually all counts of ribs or any other pattern are always a factor of 360. So, possible numbers are 2, 3, 4, 5, 6, 8, 10, 12, 15, 18, 20, 24
, 30, 36, 45, 60, 72, 90, 120, 180, and 360.
Do you see the flaw in my argument? Arguably the most frequently used rib dip-mould was 16-rib, not in my list. Still, not too difficult to make, either by rotating by 22Â½Â° between each pattern, or by rotating 45Â° for the first eight patterns, and setting up again for the in-between patterns. 16 is the only mould pattern repeat I have found which is not in this list of factors.
... and your bowls are not Walsh.