The man a sets out from a and comes as far as b, which are 32 [braccia], gaining backward shovelful by shovelful, each of which is 1/6 of a braccio thick; therefore multiply 32 braccia by the 6 shovelfuls that go to a braccio and you will have the sum of 192/6 of braccia, all of which have to be walked forward and then carried back, that is, that the first shovelful be counted as the one that is after the 4 braccia by which you have withdrawn from the bank, and that you can throw no more earth that reaches that bank; you will go forward the less by the thickness of such a shovelful, and then, having thrown it, you go back 2/6 of a braccio to take up the next, and then return forward those 2/6, and throw such earth, and then go back those 2/6 and 1 more to reload the shovel anew; and so, in such order, you always go back as much as you went forward and 1/6 more, and so it is done up to the number of the aforesaid 192 sixths, the sum of which, between going and returning, is 18528 sixths, only those of going forward, and as many again are those of returning backward, which in sum would be 37056 sixths, which will be found by the rule of progression. Now you know that one hour is divided into 1080 tempi, and that in such exercises one takes 3 paces, walking, per tempo, which would be, or would contain in themselves, 18/6 of braccia per tempo. Therefore if you divide 37056 sixths by 18, you will be able to see in how much time this man will make these paces; divide then, and you will find that such movements backward and forward are made in 2058 tempi and 2/3. Add to this the 3 tempi that go for every shovelful with its throwing, which were, in 32 braccia at 6 shovelfuls per braccio, 192 shovelfuls. And each shovelful containing in itself, as I said, 3 tempi, multiply the said 192 shovelfuls by the 3 tempi and you will find 576 tempi, which added to the first are 2634 tempi and 2/3. Therefore divide these tempi by the 1080 tempi of the hour and you will find it to be 2 hours and 54/180. Now this man carried in this time 192 spadefuls of earth; divide them by the 6 spadefuls that go to make a barrow, and you will find in such number 32 barrows, which at 20 barrows to the cart make 3/5 of a cart. Now, to know what falls to him per hour, do it by the rule of three, saying: if in 2 hours and 54/180 this workman gives me one cart and 3/5, how much will he give in one hour?