[ »73 1 
Tab. IV. or Fig. 4* 
The Flan of the Clepfydra to its full Tiimenfon. 
The Cafe uu inclofes the whole Machine, except 
the Ciftern that fupplies the Siphon d y which may 
be placed at any Diftance from it, as is moft conve- 
venient, provided the ifluingLeg d, of the Siphon is 
lengthened out fo as to give a conftant Stream into 
the Canal e . This Cafe uu fupports the Axis of the 
Cylinder*? behind, and the Dial-Plate before 5 in 
the Centre of which turns the Axis 0 , with the Index 
k at its Extremity, being the Minute-Hand. The 
Hours may be defcribed by two common Wheels, as 
in ordinary Clock-work. For cheap Work, Chains 
palling round Pulleys would do inftead of Wheels 
with Teeth. 
The Motion of the Clepfydra is ejfeEted in the fol- 
lowing Manner : 
The fhort Leg of the Siphon d is placed in a Cif- 
tern, with its Mouth fomething below the Mouth of 
the Wafte-Pipe; which Ciftern is fupplied with a 
conftant Stream, rather more than runs out at the 
Siphon d; which Overplus going off at the Wafte- 
Pipe, the Water always remains at the fame Height 
in the Ciftern, and yet always delivers a conftant and 
equal Flow into the Canal e e •, confequently, there is 
not the leaft Intermiflion. As the End of the Canal 
e , fixed to the Pipe /i, is in the Figure the lowed* 
the Water runs all thro' the Pip efi, into the Vef- 
fel^ 1, till it runs over the Top of the Tantalus t 5 
when it immediately runs out at ; into the Cup 
at 
