Propositiones ad Acuendos Juvenes/Problems/29 - De Civitate Rotunda/Solution 2
Propositiones ad Acuendos Juvenes by Alcuin of York: Problem $29$
- There is a round town, $8000$ feet in circumference.
Solution
The boundary of the town is $8000$ feet.
Take a quarter of $8000$, getting $2000$.
Again take a third of $8000$, getting $2666$.
Take the half of $2000$, which is $1000$, and the half of $2666$, which is $1333$.
Not the thirtieth part of $1333$ is $44$.
Likewise the twentieth part of $1000$ is $50$.
$50$ times $44$ is $2200$.
Then form $2200$ times $4$ whch is $8800$.
This is the total number of houses.
Historical Note
The actual area of the town is approximately $8488$ house areas.
Using $\AA = \dfrac {C^2} {16}$ as in $25$: De Campo Rotundo, the area is approximately $6667$ house areas.
Alcuin assumes the circle contains a $1600 \times 2400$ rectangle, but such a circle could hold over $10 \, 000$ house areas.
David Singmaster reports that he managed to fit $8307$ in, but suspects it may be possible to do better.
Sources
- c. 800: Alcuin of York: Propositiones ad Acuendos Juvenes
- 1992: John Hadley/2 and David Singmaster: Problems to Sharpen the Young (Math. Gazette Vol. 76, no. 475: pp. 102 – 126) www.jstor.org/stable/3620384