In 1993, R. D. Stevenson and R. J. Wassersug published correspondence in "Nature" summarizing measurements and calculations of peak and sustained work rates of a horse. Citing measurements made at the 1926 Iowa State Fair, they reported that the peak power over a few seconds has been measured to be as high as and also observed that for sustained activity, a work rate of about per horse is consistent with agricultural advice from both the 19th and 20th centuries and also consistent with a work rate of about 4 times the basal rate expended by other vertebrates for sustained activity.