“chemically terminating the sequence randomly, at any of the four nucleotides along the chain. They then had to find the molecular mass of what was left from the chemical reaction. The molecular masses of the products were determined by separating each according to its size on a large gel. By applying an electrical field across through the gel, the chopped up bits of DNA could be forced to move through the gel. The smaller bits moved faster, and hence further than the larger bits and by measuring how far each bit moved, one could calculate which nucleotide came first, second, third, and so on.”