The amount of work done by any form of engine may be expressed as so many kilogrammetres per hour. That is to say, the numbers of kilogrammes it could raise to the height of one metre in that time.

The left ventricle moves with each systole about 0.188 (Volk-lriann) kilogrammes of fluid against an arterial pressure corresponding to 3.21 (Donders) metres height of blood, i. e., 0.188 X 3.21 = 0.604 kilogrammetres for each systole. This at 75 per minute for 23 hours would be 0.604 X 75 X 60 X 24 = 65,230 kilogrammetres.

The right ventricle does about one-third as much work as the left, making a total of 86,970 kilogrammetres for the ventricles. Or, in other words, the heart of a man weighing twelve stone does as much work in twenty-four hours as would be required to lift his body 1248 yards into the air, i. e., nearly ten times as high as the steeple of St. Paul's Cathedral.