Furlong in the Hoddle Grid of Melbourne are also one furlong in length. Much of Ontario, Canada, was originally surveyed on a ten-furlong grid, with major roads being laid out along the grid lines. Now that distances are shown on road signs in kilometres, these major roads are almost exactly two kilometres apart. The exits on highways running through Toronto, for example, are generally at intervals of two kilometres. The furlong is also a base unit of the humorous FFF system of units. The exact conversion of the furlong to SI units varies slightly among English-speaking countries. In Canada and the
How many angels can dance on the head of a pin? about how many could perch at the same time on the head of a pin"". Dorothy L. Sayers argued that the question was "simply a debating exercise" and that the answer "usually adjudged correct" was stated as, "Angels are pure intelligences, not material, but limited, so that they have location in space, but not extension." Sayers compares the question to that of how many people's thoughts can be concentrated upon a particular pin at the same time. She concludes that infinitely many angels can be located on the head of a pin, since they do not occupy any space there: