Page:Philosophical Transactions - Volume 002.djvu/40

 In the same Trials made with this Instrument in the said River of Thames, it has been found, that there was no difference in time, between the submersions of the Ball at the greatest depth, when it rose two Wherry's length from the place where it was let fall (being carried by the Current of the Tyde) and when it rose onely a Yard, or so, from the same place, where it was let down: And that it must be so in great depths and stronger Currents, is as certain, as easie to be demonstrated.

And if it be alledged, that it must be known, when a Light Body ascends from the bottom of the Water to the Top, in what proportion of time it rises; it may be considered, that in this Experiment the times of the Descent and Ascent are both taken and computed together; so that, for this purpose, there needs not the nicety, which is alledged.

F other Experiments of this way of sounding without a Line, made by the Noble Lord Viscount Brounker, Sir Robert Moray Knight, and Mr. Hook, in the Channel at Sheerness; the following account was given, Vid.

The Ball (B) and the Lead (B) were let down at 16 fathom 5 and the Ball returned in 48 single strokes of a Pendulum, held in the hand, vibrating 58 single strokes in a Minute.

A second time repeated with the same success; therefore, the motion was 4 foot every second.

Again the Ball (A) and the Lead (B) whose Nail was bended into a sharper Angle; the Ball returned in 39 strokes. A second time repeated with the same success at the same depth.

Ball (B) Lead (B:) in which trial the Line, not being clear, stopped a little the motion; the Ball returned in 47 at the same depth. Rh