86) are useful, but inadequate to our purpose; for one thing, they often exaggerate the width of the streets.

One really needs actual measurements made on the spot.
In this system perhaps the most peculiar feature is the intermixture of square and oblong 'insulae'.

It is not merely the variation which can be traced in Priene (fig.

5), where some blocks are rather more square or oblong than others, but where all approach the same norm.
The Roman towns which we are now considering show two varieties of house-blocks.

Sometimes the blocks are square; sometimes, perhaps more often, they are oblong approximating to a square, like the blocks of Priene.