Horses of the breed have power out of all proportion to their weight. Even a casual glance at their make-up will furnish the reasons for their fame as tug-stretchers. They are short-legged and close to the ground; the center of gravity is low, in accordance with a well-known mechanical principle which the designer of any movable engine must keep constantly in mind. The scientists tell us that the power which moves the equine engine comes from the thick, short gluteal muscles. The Suffolk is unsurpassed in the turn of his rump, while his thighs and quarters are more massively furnished than those of any other breed, thanks to the pulling contests common in England.