CusACK — Human Locomotion. 527 



breathing becomes irregular. Also wbeii asleep the respirations are 

 very regular. It is therefore to be expected that the mechanical 

 walk, that is, the walk when the thoughts of the walker are distracted 

 from the action of his walking, will be more uniform than the walk of 

 which the walker is conscious. 



The apparatus first devised for recording the velocity at short 

 intervals of a man walking was as follows : — A drum such as is used 

 for recording the vibrations of a tuning-fork was procured ; such a 

 drum is usually driven by a small motor, but in the present case to 

 the driving axle I attached a boxwood cylinder about two inches in 

 diameter, removing the ordinary driving wheel. On this cylinder 

 was wound about 30 yards of light, non-elastic string. Ordinary 

 white tea-twine answered the purpose very well. The end of this 

 string was attached to a light belt round the walker's waist, and when 

 the walker walked away from the apparatus he unwound the string 

 from the cylinder, thus driving the drum. Eound the drum was 

 attached the ordinary smoked paper, and on this a tuning-fork recorded 

 its vibrations. The tuning-fork used gave nineteen vibrations per 

 second. Now the velocity at which the drum was driven varied, 

 according to the rate at which the string was unwound, that is to 

 say, the velocity at which the man walked. If the velocity of the 

 man was uniform during each step the length of the waves recorded 

 on the drum would all be equal. This I found was not the case, but 

 the change in velocity was so small that the variation in the length 

 of the waves could only be perceived with difficulty. The above 

 apparatus was found unsuitable, inasmuch as the drum jerked when 

 the motion was irregular, also the motion of the drum was difficult to 

 control. 



The following modification was made and was found more con- 

 venient, as the recording apparatus could be placed in a room away 

 from where the man was walking, communication being made by 

 wires and an electric current. 



The boxwood cylinder was replaced by the original driving pulley, 

 and the drum was driven by an electric motor. 



The motion of the drum was now quite uniform, and its velocity 

 easily controlled. The tuning-fork vibrations on the drum now merely 

 sound to mark time, and were of course quite regular. To record 

 the velocity of the walker the following instrument was made. A box- 

 wood cylinder about 6 inches long and 3 inches in diameter was 

 turned on. a steel mandrel, which mandrel afterwards served as the 

 axle. To one end of the cylinder was attached a commutator, with 



