You use sugar nips, just like when sugar was sold as cones or loaves:
Households bought their white sugar in tall, conical loaves, from which pieces were broken off with special iron sugar-cutters (
sugar nips). Shaped something like very large heavy pliers with sharp blades attached to the cutting sides, these cutters had to be strong and tough, because the loaves were large, about 14 inches (36 cm) in diameter at the base, and 3 feet (0.91 m) [15th century]...In those days, sugar was used with great care, and one loaf lasted a long time. The weight would probably have been about 30 pounds (14 kg). Later, the weight of a loaf varied from 5 to 35 pounds (2.3 to 15.9 kg), according to the moulds used by any one refinery. A common size was 14 pounds (6.4 kg), but the finest sugar from Madeira came in small loaves of only 3 to 4 pounds (1.4 to 1.8 kg) in weight...Up till late Victorian times household sugar remained very little changed and sugar loaves were still common and continued so until well into the twentieth century...
— Elizabeth David,
English Bread and Yeast Cookery. Middlesex: Penguin, 1977 (p. 139)