To make Capons […] [S]ome for this Purpoſe make it their Buſineſs after Harveſt-time to go to Markets for buying up Chickens, and between Michaelmas and All-hollantide caponize the Cocks, when they have got large enough to have Stones [i.e., testes] of ſuch a Bigneſs that they may be pulled out; for if they are too little, it can't be done; […] [M]aking a Cut here big enough to put her Finger in, which ſhe thruſts under the Guts, and with it rakes or tears out the Stone that lies neareſt to it. This done, ſhe performs the very ſame Operation on the other Side of the Cock's Body, and there takes out the other Stone; then ſhe ſtitches up the Wounds, and lets the Fowl go about as at other Times, till the Capon is fatted in a Coup, which is commonly done from Chriſtmas to Candlemas, and after.
Source: wiktionary