2 Z

Hydraulics.

From this Preffure of Fluids* as ttic

Cause, we can estimate the various Mo-menta

3. First, The Air’s Resistance is an Obstruction tothe Jet, and diminishes its Height; and since we knowthat the Resistance of Fluids is proportional to theSquares of the Velocity, (Annot. LXVIII. Art. 4.)

Mid the Deficiency of Height HI is proportional to theResistance; therefore a Jet that plays with a doubleVelocity will have that Deficiency four Times as great;

3n d with three Times the Velocity, nine Times as

great; and so on. _

4 - The second Impediment is the Friction against

the Sides of the Hole, and the Adjutage at G ; andsince this is in proportion to the Quantity of Surface inthe Hole, it will be greater in a small Hole than a large0rte , in respect of the Body of the Jet, or spoutingWater ; because the Jet will increase in Magnitude withthe Square of the Diameter of the Hole, whereas theResistance will increase only with the Diameter imp y.

Or a Hole of twice the Diameter emits four 1 lines theWater, and gives but twice the Resistance. This makesa small Jet rife to a less Height than a large one, from

the fame Reservoir.

5. A third Impediment arises from hence, that sincedll the Particles set out from G with an equal Velocity,and this Velocity is continually diminishing, it followsthat the Velocity of the inferior Parts is greater thanthe Velocity of the Parts above them, and thereforettmst in some Degree strike against them ; by this Im-pulse (since Fluids move every way) the Particles willbe urged sideways, and the Column of the Jet be-come wider, and consequently shorter than it wouldotherwise be.

6. The fourth Cause why Jets do not rife to theHeight of the Reservoirs, is because the Water upon theTop of the Jet does not immediately run off, butspreading into a Head, lies with its Weight upon thyascending Water below, and hinders it from rising sohigh as it would do. This will appear by incliningC a. the