And the answer is: Because the catgut on the racquet.
"The Radio Boys at the Sending Station" by Allen Chapman
Sterilised silk and catgut for sutures.
"The Elements of Bacteriological Technique" by John William Henry Eyre
Two small girls are scraping doleful strains from the sad catgut of violins nearly as big as themselves.
"The Atlantic Monthly, Volume 20, No. 121, November, 1867" by Various
Do you think I can't scrape catgut as well as Pere Paragot?
"The Belovéd Vagabond" by William J. Locke
They should be of catgut, and if you tune them in unison, the sound will be sweeter than if they are tuned in thirds or fifths.
"Harper's Young People, April 6, 1880" by Various
A simple hygrometer can be made by a piece of catgut and a straw.
"Harper's Young People, August 17, 1880" by Various
Ods catgut and fiddlesticks!
"The Bow, Its History, Manufacture and Use" by Henry Saint-George
I hear Mrs. Catgut has some of the prettiest caps arrived you ever saw.
"The Contrast" by Royall Tyler
The banjoes was made of round pieces of wood, civered with sheepskin and strung with catgut strings.
"Slave Narratives: a Folk History of Slavery in the United States From Interviews with Former Slaves" by Work Projects Administration
Fiddlers, to your catgut!
"The Works of Robert Louis Stevenson, Volume XV" by Robert Louis Stevenson