178 Transactions. — Miscellaneous. 



edges of its planes or radii elevated, and as this requires to be turned in an 

 opposite direction, tlierefore the car is kept from rotating. In the model 

 there is a crank in each of the axes and at the same height, and each crank 

 is connected by a rod to a vertical pedal common to both ; in this manner both 

 wheels are compelled to rotate with the same speed but in opposite directions; 

 it then follows that by turning only one of the cranks by the hand the whole 

 apparatus would by reaction be guided in azimuth when requii-ed. In order 

 to apply any power or force we must have a basis or part which acts as a 

 fulcrum wherein action and reaction can have full sway. In birds and all 

 flying creatures each wing is panned with another. 



In the working compartment of this model the attempt has been made 

 to so arrange the i3arts as to utiHze the immense force which the human 

 form is so eminently capable of exerting. The machinery is reduced to the 

 simplest form, namely the two perpendicular winches between which manual 

 power can be exerted in a sitting posture. These winches are merely U 

 shaped bends in the prolonged axes of the tension wheels. Let us consider 

 the power that can be exerted by the pull stroke. It is considered that, in 

 rowing, manual power is applied in a very advantageous manner : the 

 feet are firmly planted and the arms and shoulders react from them. It 

 will be seen by the model that the feet can be placed on the nearly vertical 

 pedal ; great force could therefore be exerted by the legs alone : in fact 

 great force can be exerted by the human form between two cranks in almost 

 every part of the revolution when they go round in opposite directions. It 

 is not expected that full manual power can be exerted continuously, as it is 

 found that most work is done when there is a short period of rest, as in 

 rowing ; but it might be expedient to exert full power at some particular 

 part of the revolution, hence the present arrangement whereby the feet or 

 hands can be used either together or alone, thus avoiding dead points and 

 allowing of the hands being used for steering. That far more power can be 

 exerted by the legs than by the arms is- easily proved by the fact of the 

 weight of the body being raised for a whole day long in scaling mountains, 

 whereas if the arms were to be used in pulling the body up under a ladder 

 or an inclined rope, a few minutes would lead to exhaustion ; and even if 

 the power of the arms alone were used in any other mechanical arrange- 

 ment, it would still be fatiguing. The arms working however between two 

 vertical cranks allows of power being exerted in four ways ; 1st., in pulling 

 from the front, as in rowing; 2nd., in pushing in the opposite du-ection or 

 forwards ; 3rd., in pulling the cranks nearer to the body laterally ; and 4th., 

 in the reverse du-ection or pushing laterally outwards ; and as this possibility 

 of change is really important from its alloA^dng one set of muscles to rest 

 whilst others are operating, an account of a simple arrangement for varying 



