March, i{ 



A ROWING INDICATOR. 



179 



The indicator replaces the back thowl of the rowlock, so that in 

 rowing the stroke the oar presses against the front face (BC, Fig. 2) 

 of the instrument with the button at C. The instrument con- 

 sequently turns with the oar, and carries the indicating point, E, over 

 the card fixed to the plate, DD. If the stroke could be rowed with- 

 out pressure against the indicator, the indicating point would simply 



Fig. 1. — Photograph of Indicator. 



describe a circle. Pressure, however, tends to drive the face back 

 and make the back-plate, AI, turn about B and compress the spring, 

 SS, and then the pencil moves nearly radially outwards. The plate, 

 DD, is fixed to the axle, A, which at its bottom end screws on to the 



Fig. 2. — Plan of Indicator. 



outrigger. In this way, while rowing the stroke, a diagram (Fig. 3) 

 is drawn, the " base-line " being formed as the oar is coming forward. 

 The pencil (in reality a brass point working on "metallic paper") is 

 fixed to an arm which turns freely about the pivot, K, and is 

 usually held off the card by a rail (FF). The diagram, then, is only 

 traced when the rail is depressed by a string (G), which is under the 



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