1X>\| 



SOME MORE ROWING EXPEIUMEXTS 



101 



APPENDIX I 



The Oak Used and Constants of Indicatob 



The axle of the Indicator is 1" below the button. Midway between the hands 

 is 41-5" above this point, and the tip of the blade is 102" below it. The centre of 

 pressure of the blade was calculated on the rough assumption that the pressure at a 

 point varied as the velocity, and it was further assumed that the turning point occupied 

 its mean position 36" above the tip. 



The centre of pressure thus calculated is 9 "6" above the tip. 



P_ F _ R 



Hence (see Fig. 13) 83~i84 - 267' 



The instrument was calibrated against a spring balance, using a lever with a 

 mechanical advantage of 3 - 07, and a series of experiments with the spring used 

 throughout, showed 1" on diagram = 319 lbs. pressure or a pull of 220 lbs. 



The radius of the drum is 2" -02, so that 1" of base line on the diagram represents 

 motion of .F=1 "71 feet. 



184 

 Finally, 1 square inch of diagram represents 319 x — - x 1*71 or 377//. lbs. 



APPENDIX II 



Efficiency of a Stroke in Rowing 



1 

 F 



1 



I 



Ki<;. 13. — Dimensions of Oai\ 



Let A be ' turning 

 point' while oar turns 

 through an angle dd, 

 B centre of pressure 

 of the blade, C the 

 button, D centre of 

 pull on handle of the 

 oar. 



Work delivered to water = P x ABd0=R^-AB dd. 

 Work done by man = FCD d0=R^-CD d$. 



J 1:1) 



So assuming B a fixed point, 



Efficiency = 1 



A 



4£ de 



CBde 



2X-AB-A0 

 2B-CB-A6 



practically. 



Si) between successive positions of the oar was measured for all pairs of positions, and 

 a curve drawn, from which corrected values were deduced. 



R was measured in an arbitrary scale for corresponding values of 8 on C, Fig. 7, and 

 . / /.' on Fig. 



A table was then constructed as under : — 



Then by summation : — 



2RA0= 10497, BC 



ZB- A £-A6 = 32i>70 



'.'■1 



E- 1 - 



32570 



1049-7x92 



= -666. 



