644 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 
of it all lies the question of artificial power and the harnessing in 
compact and convenient form the stored-up sources of energy in 
nature in order to overcome the opposing resistance, and we can 
realize that, although we have obviously reached the limits of animal 
locomotion, we are far from having reached any limitation in regard 
to the speed of self-propelled machines. We see that in all three 
forms of locomotion—earth, air, and water—the advance has been far 
more rapid during the last few years than ever before, and we can 
realize that there is yet a considerable margin by which speed of 
traveling could be increased as the demand for it is made; and 
nothing is more certain than that the demand will be made. 
I began my lecture by pointing out why speed was instinctively 
taken as a test and a measure of locomotion from the earliest times. 
968,000 
m0 Bx 660 (870 1850 1690 Roo 1907 
YEAR 
Fig. 6.—Progress in Atlantic steamers (Cunard). 
Shakespeare makes one of his characters say, ‘‘The spirit of the time 
shall teach me speed,” but he might have said this of any period 
equally with that of King John, though never more so than of to-day, 
for the changes in the requirements of civilization have only altered 
in detail, and speed is of as much importance as ever in the struggle 
of life. The probably unconscious recognition of this fact has always 
led question of speed to be raised as prime factors in proposals for 
new modes of locomotion, and it is interesting to look back only 
a comparatively few years to see, in raising these views, this was 
always the case, but how little any ideas of future possibilities were 
realized. When George Stephenson, backed up by a few courageous 
and enterprising men, was fighting the battle of the railway and in 
