114 HYDROSTATICS. 



inches below the surface of the water at K; ant! 

 then the leaden bottom, G, will be plunged to the 

 depth of somewhat more than eleven times its own 

 thickness. Holding the tube at that depth, you 

 may let go the thread at L, and the lead will not 

 fall from the tube, but will be kept to it by the 

 upward pressure of the water below it, occasioned 

 by the height of the water at K, above the level 

 of the lead: for as lead is 1.133 times as heavy as 

 its bulk of water, and is in this experiment im- 

 mersed to a depth somewhat more than 1.133 times, 

 its thickness, and no water getting into the tube 

 between it and the lead, the column of water 7 

 Gab, below the lead, is pressed upward against it 

 by the water all around the tube; which water 

 being a little more than 1.133 times as high as the 

 lead is thick, is sufficient to balance and support 

 the lead. If a little water be poured into the tube 

 upon the lead, it will increase the weight upon 

 the column of water under the lead, and cause the 

 lead to fall from the tube to the bottom of the glass- 

 vessel. Or if the tube be raised a little in the water, 

 the lead will fall by its own weight, which will then 

 be too great for the pressure of the water round the 

 tube, upon the column of water below it. 



In like manner, a piece of wood may be made to 

 lie at the bottom of water, by keeping the water 

 from pressing on its under surface. Let two pieces 

 of wood be planed quite flat, so as no water may 

 get between them when they are put together; let 

 one of the pieces, as a b, be cemented to the bot- 

 tom of the vessel, A B (Fig. 7.), and the other 

 piece be laid flat and close upon it, and held down 

 to it by a stick, whilst water is poured into a 

 vessel; then remove the stick, and the upper piece 





