( M4 ) 
till it is all emptied* and as it difcharges it felf into 
another Tantalus T V (whofe Syphon is at V) ^ this 
laft Tantalus will alfo, when full, begin to run out, 
and its Water go down to x Y o. 
If the Plug be let down gradually, as foon as the 
W ater begins to run out of the lad Tantalus TV, (and 
the firft Tantalus R S be cover’d fo as to be conceal’d 
from Sight) it will appear to the Lookers on, That 
the Cavity TV, reprefenting a Pond near an ebbing 
and flowing River (as I am credibly inform’d there 
is fuch an one at Greenhive in Kent , between Lo?idon 
and Grave fend) always rifes, whilft tire Water at N O 
(or the Tide) falls to LM; and always finks whilft 
the Water at LM (or the Tide) rifes to OL. ' T 
t - nr ' *: . W i " ‘ . 
EXPERIMENT II. 
Let the Water in the Box A BCD not be made ufe 
of } only the Veil'd Z be fill’d every half Hour: It 
will empty it felf in the Space of a Quarter of an Hour, 
falling like Rain, and dropping alfo thro’ the Leaden 
Platform ef into the hidden Tantalus RS, which will 
not begin to run till this artificial Rain is over :• Then in 
a Quarter of an Hour more, the Tantalus R S will have 
emptied it felf into the viiible Tantalus T V, which 
will be filling all the Time .after Z has done running • 
(or in the dry Seafon) Hildas foon as T V is full, it will 
begin to run out thro* its Syphon V, at the End of the 
half Hour, when the Vdfel Z or Sieve runs again , that 
is, at the Return of the rainy Seafon. 
This laft Experiment may eafily be applied to thofe 
Ponds, or thofe Brooks; that are high irt dry Weafther, 
and low in wet Weather of which Kind,' I am told-, 
there is a Brook at Lambonrn in Berk/hire. 
