of Lever does the Oar belong f 59 



nish the advantage and increase the effort, until, when the 

 hands were applied at the rowlock, power and resistance 

 would be exactly equal, and the boat would still be moved, 

 only with one third more effort. If we continued to move the 

 hands till they were applied to the oar at one fourth of its 

 length outside the rowlock, we should still propel the boat 

 forwards, though with twice the original effort. Finally, if 

 we contrived by a rope to pull at the blade of the oar (that is, 

 at the fulcrum) we should produce no motion whatever. It 

 is needless to point out how unlike these the actual facts are. 

 If the power is applied to the oar at the rowlock no effect is 

 produced ; if it is applied outside, the motion of the boat is 

 reversed ; and the maximum effect in this direction is pro- 

 duced if the power is applied to the blade. This is proof that 

 the true fulcrum (relative to the rower) is at the rowlock, 

 On one hypothesis only is the oar a lever of the second order; 

 viz. if the rower stands on terra firma. In that case all the 

 consequences above mentioned as resulting from a change in 

 the point of application of the power will really result. 



Let us put another hypothetical case. Suppose the rower 

 to be in the boat as usual, but the boat to be fixed, while the 

 oar presses against another boat which is free to move. In 

 this case the oar is manifestly a lever of the first order ; but 

 the relative position and action of the oar, the power, and the 

 resistance are in every respect precisely the same as in ordinary 

 rowing. 



The fact is that writers on Mechanics have strangely enough 

 neglected to consider that the rower is in the boat, and that 

 therefore the reaction of his effort is against the boat itself. To 

 him the boat is terra firma. It will perhaps be said that we 

 have only to take this reaction into account, and that then the 

 account given of the oar as a lever of the second order will 

 appear to be correct. True; and we might similarly treat 

 almost any lever of the first order as belonging to the second ; 

 but when writers tell us that the oar is a lever of such and 

 such a kind, they are supposed to mean that it is so relatively 

 to the rower, not relatively to the universe. 



I find it stated in some books on Mechanics that the amount 

 of work done in rowing has not been estimated ; and this is 

 no wonder, if the nature of the effort has been so misconceived. 

 It cannot be said that the difference is unimportant practically, 

 if this means that it does not matter which theory we act on. 

 If we suppose, as above, that the distance from the rowlock to 

 the handle is successively one eighth, one fourth, one third, 

 and one half the length of the oar, then the proportion of 

 power to resistance would be successively : — 



