( n* ) 
derived from R will, after fome time, begin to run 
again, and encreafe ’till the Water rifes in the Cavern 
to N ; after which it will decreafe, and at length 
ftop. But if the Difcharge of the Syphon only keeps 
the Surface of the Water below R, without emptying 
the Cavern, then the Fountain derived from R (hall be 
dried up, fo long as the Stream at O continues en- 
creafed ; and fhall run again when the faid Feeding- 
Stream is leffened. Thus we may have a Spring 
which fhall run all Summer, and be dry all Winter: 
Such a Spring will encreafe juft before . it begins to 
fail, i. e. whilft the Water in the Cavern is rifing to 
N, will be dried up fooner in a wet Summer, and 
break out later in a wet Winter, contrary to the Na- 
ture of other Springs. Which Particulars are worthy 
of Obfervation in fuch fort of Springs (of which 
it is faid we have fome in England ) and will ferve 
to difcover, whether they are occasioned by this kind 
of Machinery, or not. 
If the Syphon Fig. 3. MNP, of the Refervoir 
ABCD, having no Out-let at R,(hould d ifcharge itfelf into 
a fecond Refervoir EFGH of afmaller Capacity, but 
furnifhed with a Syphon S T V, which difcharges the 
Water more plentifully than it comes in j a Fountain 
derived from this fecond Syphon S T V would flow 
and intermit, whilft the firft Syphon MNP conti- 
nued running^ i. e. ’till the great Refervoir A BCD 
fhould be emptied. After which it would entirely flop, 
s till the faid Refervoir ABCD was filled again by the 
Feeding-Stream at O, and then it would flow and in- 
termit as before. 
Such a Sort of compound Fountain would be liable 
to all the Variations of the former Fountains derived 
from a fingle Refervoir, if we take the Fits of flow- 
ing 
