632 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 
/ 
We therefore now know that the limit of speed is controlled by two 
factors: ; 
(1) Physical endurance, owing to the expenditure of work occur- 
ring at an increasing rate as the speed is increased. 
(2) The physical impossibility of giving a reciprocating movement 
to the legs quicker than a certain limited period of time. 
I have prepared a chart (fig. 2) which shows the maximum recorded 
velocities of man’s progression in walking and running. The speeds 
are set up as vertical ordinates, and the abscisse represent the dis- 
tances over which the respective speeds were maintained. It will be 
MILES PER HOUR’ 
MILES 
Fig. 2.—Speed records for human muscular effort. 
seen that the maximum speed of walking is about 9 miles an hour 
for a short distance, but when the long distance of 100 miles is covered, 
the quickest rate recorded falls to 54 miles an hour. For running, 
the quickest speed which I have mentioned, viz, 214 miles an hour 
for 100 yards, falls to 74 miles an hour as the average speed for a dis- 
tance of 100 miles. 
We do not know the speed of the original historical run from Mara- 
thonto Athens, but we do know that Dorandoran the modern Marathon 
from Windsor Castle to the stadium at Shepherd’s Bush, a distance of 
