Place the half-and-half back on the heat and bring to 155 degrees (using a candy thermometer).

Bring to a boil and simmer about 12 minutes, to 220 degrees on a candy thermometer.

Cook over medium heat until it reaches 300 degrees on a candy thermometer.

I hooked a candy thermometer on the side of the pan to regulate the temperature.

Indeed, even the suggestion of a candy thermometer gets my blood pressure rising.

Heat to a temperature of about 240 degrees on a candy thermometer.

Remove lid and cook to 275 degrees on a candy thermometer.

The temperature on a candy thermometer should be 250 degrees.

Cook until a candy thermometer registers 237 to 239 (soft ball stage).

Simmer the jelly until it reaches 219 degrees on a candy thermometer, about 1 hours.