Solve the Little Pigley Farm crossnumber and find the age of Mrs.

Problem

Solve the Little Pigley Farm crossnumber and find the age of Mrs. Grooby,
Farmer Dunk's mother-in-law.

Taken from _The Penguin Book of Curious and Interesting Puzzles_, by
David Wells.

448. Little Pigley Farm, 1935

This puzzle is from _The Strand Problems Book_ by W. T. Williams, who
composed puzzles for _John O'London's Weekly_, and G. H. Savage, who
published in _The Strand Magazine_ [Editor: "_The Stand Magazine_" in
the original; corrected by the contributor in a follow-up note].

+--+--+--+--+--+--+--+
| 1|  | 2| 3|  |XX| 4|
+--+--+--+--+--+--+--+
|  |XX| 5|  |XX| 6|  |
+--+--+--+--+--+--+--+
|  |XX|  |XX| 7|  |  |
+--+--+--+--+--+--+--+
|XX| 8|  | 9|  |XX|XX|
+--+--+--+--+--+--+--+
|10|  |XX|11|  |12|13|
+--+--+--+--+--+--+--+
|  |XX|XX|XX|14|  |  |
+--+--+--+--+--+--+--+
|15|  |XX|16|  |XX|  |
+--+--+--+--+--+--+--+

Note:  One of the "across" numbers is the same as one of the "downs".
This is the only case of identity, though one number in the puzzle
(relating to something quite different) happens to be the area in roods
of the rectangular field known as Dog's Mead.  Equipped with this
information and the homely items that follow, the reader is invited
to discover the jealously guarded secret, the age of Mrs. Grooby, Farmer
Dunk's mother-in-law.

Readers may like to know that 1 acre was 4840 square yards and 1 rood
was one quarter of an acre.  Also there were 20 shillings in 1 pound
sterling.

Across                                  Down

 1. Area of Dog's Mead in square         1. Value in shillings per acre of
    yards.                                  Dog's Mead.
 5. Age of Farmer Dunk's daughter,       2. The square of Mrs. Grooby's age.
    Martha.                              3. Age of Mary, Farmer's youngest.
 6. Difference in yards of length        4. Value of Dog's Mead in pounds
    and breadth of Dog's Mead.              sterling.
 7. Number of roods in Dog's Mead x      6. Age of Farmer's firstborn, Ted,
    9 down.                                 who will be twice as old as
 8. Date (AD) when Little Pigley            Mary next year.
    came into the occupation of the      7. Square of number of yards in
    Dunk family.                            breadth of Dog's Mead.
10. Farmer Dunk's age.                   8. Number of minutes Farmer takes
11. The year when Mary was born.            to walk 1 1/3 times round Dog's
14. Perimeter in yards of Dog's             Mead.
    Mead.                                9. See 10 down.
15. The cube of Farmer's walking        10. 10 across x 9 down.
    speed in miles per hour.            12. One more than the sum of digits
16. 15 across - 9 down.                     in column 2.
                                        13. Length of tenure (in years) of
                                            Little Pigley by the Dunks.

[ Editor: sent to the archive by Chris Long <clong@cnj.digex.net>, who
called it *the* classic crossnumber puzzle. ]