One braccio per mile of descent gives, over 25 miles, 25 braccia, which is a little more than from here to the foot of Serravalle. And if the earth of the bed drinks the water, let the nearest turbid river be made to pass through it, and it will be healed. And if this is not enough, let the small livestock, that is pigs, sheep and goats, be driven over that place for several days, and it will without doubt be healed.

Cost of the Pistoia canal, with 20 braccia of canal and 20 braccia of road, so that every 40 braccia of length takes one staioro of land. And it is 25 miles as far as Serravalle. First I will reckon how many staiora there are per mile, together with the price of those staiora, putting one plot against another at 10 ducats each. Then I will say: if 40 braccia of canal, which is one staioro between canal and road on one side—if 40 give me 10 ducats, what will 3000 braccia give me, which is a mile? It will give me 750 ducats per mile, which over 25 miles amounts to 18,750 ducats; at 75 staiora per mile they come in all to 1,875 staiora, over 25 miles of canal 20 braccia wide with a road 20 wide.

And if we make 16 braccia of canal and 14 of road, a quarter of the cost will be taken off, but it will be no great matter, because between canal and road it would come to 30 braccia in all.

And because the road of such a canal would be straight and very short, going to Prato and Pistoia, the old road could in great part be sold to those who have their holdings upon it, since by its excessive length it occupies far more country than the new road would.