To test sugar syrups:

-A bowl of cold water by the stove
-A teaspoon
-A teatowel

Take a half-tsp of syrup with the spoon. Dip your fingers in cold water, wipe them on the tea towel (wet fingers will alter the 'feel' of the syrup). Take the spooned syrup between thumb and forefinger and feel its texture:

107°c- vaseline
108°c- short thread (when testing the tackiness, you'll see threads of up to 5mm between thum and forefinger)
110°c- long thread (idem, 3-4cm threads)
115°c- soft ball (you'll be able to roll a squidgy ball of syrup between your fingers)
120°c- firm ball
124°c- hard ball

Do not touch the syrups above this temperature!!