II. THEIR USE.
In order to understand the true action in a slide, it will be well to recall the action of fixed-seat rowing. On the fixed seat the swing of the body does the main work, being supported by the legs, which are rigid and bent.
On a slide the legs extend gradually, while at the same time they support the body. On a fixed seat the body moves as the radius of a circle that is stationary ; on a slide the body moves as the radius of a circle which is itself in motion. Suppose a threepenny-piece and a half-crown placed alongside of each other, concentrically, with a common pivot. Let the three- penny-piece roll for a certain distance on the edge of a card. Then any point in the circumference of the half-crown will move through a curve called a ‘trochoid.’ This is practically the sort of curve described by the head or shoulders of an oars- man who rows upon a sliding seat.
The actual gain of rowing power by means of this mechanism is considerable. The exact extent of it is not easy to arrive at, there being various factors to be taken into consideration.
In the first place, the length of reach, or of the ‘stroke,’ is considerably increased. Mr. Brickwood in 1873 conducted some scientific experiments on dry land upon this subject, in con- junction with the editor of the ‘ Field’ and Mr. F. Gulston. The result of these measurements was to demonstrate (in the person of Mr. F. Gulston)a gain of about 18 inches in length of stroke upon a 9-inch slide.
In 1881 some casual experiments of a similar sort were con- ducted on a lawn at Marlow by the Oxford crew then training there. The writer was present, and, so far as he remembers, the results practically confirmed the estimate of Mr. Brickwood above recorded, allowance being made for the fact that the gentleman by means of whose body the ideal stroke was measured at Marlow was longer-bodied and longer in the leg than Mr. Gulston.
