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the mare, the fubjedt of the prefent letter, though 
fixteen years old, gave no figns of being in pain till 
about three months before her death, when fhe would 
frequently lie down, and roll about. And it is the 
more extraordinary, that, large as the ftone was (and 
it mull have been very large for a long time) it did 
not difable the mare from doing her ufual work for 
a more confiderable time before her death ; which 
did not feem to be occafioned by the (tone, fhe dying 
near her foaling-time j nor fo far difturb her oeco- 
nomy, as to prevent her propagating her fpecies. 
The Earl of Macclesfield, our moft worthy Pre- 
fident, Dr. Birch, and feveral of our friends, who 
have feen this ftone, join with me in thanks to you 
for this communication. 
In the year 1746, his Grace the Duke of Rich- 
mond prefented to the Society a ftone found in the 
colon of a horfe, the circumference of which was 
fixteen inches. His Grace at the fame time prefented 
fome other ftones, found in the inteftines of a mare, 
which were polifhed like bezoar. It was very re- 
markable, that two of thefe ftones, when fawed 
afunder, were found to have been formed each upon 
an iron nail, as a nucleus. 
I fhall embrace every opportunity of (hewing you, 
that I am, with the greateft refpedt, 
Dear Sir, 
Your moft obliged and obedient fervant, 
W. Watfon. 
XCVII. 
