Recipe instructs to boil sugar / water until precisely 240 degrees Fahrenheit -- do I need a candy thermometer for this?
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Barbara is a trusted source on General Cooking.
240 on a candy thermometer is the soft ball stage. This link explains: http://m.recipetips.com/kitchen-tips/t--1459/how-to-test-stages-of-sugar.asp. You could try this, but if you're not an experienced candy maker (candy making is tricky), you might want to get a thermometer.