the constant height of the water in the reservoir, above the upper

aperture of the tube, was eleven feet eight inches ten lines, the dia-meter nf i l<a *..u„- • °

nietei’ of the tube one inch.

Length of the Tube, in Lines,Sxp. 1 431

5

Fv° of cubicinch. disc,in 1 min.

12274

12188

121(18

9232

-•* p Stream filling the tube..

3 18 ) ° (

^ Ditto not filling it.

On comparing the three first experiments, it appears, that theoiger the vertical tube is, the greater is the discharge of the wa-- r , because the contraction of the stream is less ; it is, however,mays somewhat contracted, even when it appears to fill the tube,fhi , < j om P ai ' ll )S tbe quantities of water discharged in the third andto'*. i Xper ' men * s ’ vve find the two discharges 12168, and 9282, areeac ‘l olnw near! y '“.the proportion of 13 to 10; but we have■in * la ^ t ! ,<: watei ' discharged through a thin aperture withouta r c ® ntract ’on in the stream, would be to the same aperture withthe l |, l ' act ~d stream as 16 to 10. Hence we may conclude, thatdisci ' tU ' ^ le re5ei ’ vo ‘ 1 ' and the. apertures being the same, thes i-r e ., iai S e t 11 rough a thin aperture without any contraction in thechar, 1 ' 1 ’ ] : discharge through an additional tube, and the dis-

e-irh^n' rou 3> b a similar aperture with a contracted stream, are toare c °,t. . neai 'ly as the number 1(3, 13, and 10 ; these proportionstion ii' *. lc . len dy exact for practice. Hence it is plain that an addi-vvh'ir.'i . 0 on 'y destroys in part the contraction of the stream,aDPri'n,- CO ' ltlact; ' on ' s greatest when the water passes through a thinbeino- vp a lar 8 e l ' cserv0 ' 1 '- D the additional tube, instead ofzontal * ’ or . pi ace d p r 4 the bottom of the reservoir, were hori-

■water ° r ^ . ? e d in fbe side, it would furnish the same quantity ofanerrn,. pr ° vu ed il was of tl>e same length, and that 1 he exteriorthe re W ? 8 a *\ lb? same instance from the surface of the water inWere “d-e additional tube, instead of being cylindrical,

dUrlv,r° n ' Ca ’ ha ™S ’ ts largest base nearest the reservoir, it wouldform tk?1 a Staler quantity of water. The most advantageousa »ivf>n'tl, Ca "i l>e g 'V cn > to obtaiu the greatest quantity of water inincom’mp 110 . c S lvcn aperture, is that which tlie stream assumesof a tn,n?.a^ Ut | 0ft ' e a P evture '> <?• tire tube must be of the formdiameter ., .*,7 cone ’ wl>ose smallest base should be of the samethat of aperture ; the area of the small base should be to

o the other Ionufi C *11° to 16 5 the distance from one baseefflux of watS w 1 ?p th f ““‘dimeter of the largest base. Thethin aperture emnl i ^ be a!nu ‘dant as it would be through a

not contracted. Th is form mSe T’ n W ! ,ere • h • 8trea ™. *??to obtain a certain uuantitv of "water t?, lCt " -1 - iere 14 ' s nec ' 3 ^'' ai >&c. bv a e-ml nr liVei-.i t i°‘ o 1 ll0ln a nver, an aqueduct,through additional inlvU r^rV’ bu com paring the efflux of water

Diameter of the Tubesin Lines.

the f

I

\ 6(10

$ tube,

Constant Altitude of the Wa-ter above the Tubes.

^ X ‘ £ | 3 feet 10 inches.

, ( 6} Do. not filling the (

45 ofeet 10 inches.} 10 $ tub e..!.(

| ^2 feet.|| Do. filling the tube |

g |2 feet.{ lo} I)o- not ® lin £' t- '' {

From these experiments it results, 1. “ That the discharge 1:different additional tubes, with the same altitude of the reservoiare nearly in proportion to the area of the apertures, or to tlsquares of the diameters. 2. That the discharge of water by a<ditional tubes of the same diameter, with different altitudes of wter. in the reservoir, are nearly proportional to the square rootthe altitude of the reservoir, 3. That in general the discharge

water in the same time, through different additional tubes, wivon. in.—so, U0.

Cubicinc. in1 min.1689470312933598

1222

3402

935

2603

different altitudes of water in'the same reservoir, are to each othernearly as the product of the square of the diameters of the tubesby the square root of the altitude of the reservoir.” So that, ad-ditional lubes, transmitting water, follow (amongst themselves) thesame laws as through the thin orifice. The following table wasformed from the foregoing experiments;

Constant Alti-tude in theReservoir a-bove the A-perture.

AViiter discharged in One "Minute through

-A

a hole one inchdiameter, thestream notcontracted.

An additional]Tube of OneTnch Diam.2Inches long.

A Hole 1 InchDiam. witha contractedStream. .

Feet.

Cubic Inches.

Cubic Inches.

Cubic Inches.

1

4331

3539

27^2

O

6169

5002

3S46

3

7589

6126

4710

4

8763

7070

5436

5

9797

7900

607 5

6

10732

8634

6654

7

1 1592

9340

7183

8

12392

9975

7672

9

13144

10579

8135

10

13855

11151

8574

11

14530

11693

8990

12

15180

12205

9384

13

15797

12699

9764

14

16393

13197

10130

15

1696S

13620

10472

Wafer made to issue from a pipe into the air is called a fountainor jet d’eau, and perhaps there are few things that give morepleasure to the eye than a diversity' in the play of water from afountain : but these machines give still greater pleasure in sultryclimates, where they contribute to cool the air, as well as to enli-ven the prospect. Whatever be the direction of the jet, the dis-charge of water is always the same; provided the ajutage, andthe altitude of the reservoir above it, be the same. This is a ne-cessary consequence of the equal pressure of fluids in all direc-tions. Water, spouting from a small ajutage, has sufficient velocityto carry it to the same height as the water in the reservoir ; but itnever attains entirely to this height, being prevented by variousconcurring causes; as, 1. The friction in the tubes between thereservoir and the ajutage: 2. The friction against the circum-ference of the aperture : 3. The resistance of the air to the weight,of the water at the top of the spout; for this, having lost its mo-tion, rests on the part below, and by its weight obstructs the mo-tion of the column. The resistance from this cause is so great,that the jet is frequently destroyed, the rising water being by titsand starts pressed down to the very orifice from which it spouts:but this inconvenience is remedied, by giving the jet a little incli-! nation ; for then the particles which have lost their motion up-wards do not fall back as before, but fall off from the rest, andthus do not incumber the vising fluid; hence such jets as are a lit-tle inclined will rise higher than those that are vertical. To makelarge jots rise higher than small ones, the conduit-pipe must belarge enough to furnish a sufficient quantity of water; for if theseare narrow, small jets will rise higher than those that are larger.The diameter of the conduit-pipe should therefore bear a certainproportion to that of the ajutage, to make a jet rise to the greatestpossible height, if we compare two different jets, and desire thateach should'attain its greatest altitude, the squares of the diametersof tiie conduit pipes must be to each oilier, in the compound ratio! of the ajutages, and the square root of the altitude of the reser-voir. Thus, if we know the diameter that ought tc be given toa conduit-pipe, to furnish water tor the discharge of a given aju-tage, with a reservoir of a given altitude, v.e may determine thediameter of another tube, to feed a given ajutage with a reservoirof a given altitude. Experience has shewn, that, for an ajutagesix lines diameter, with a reservoir of 52 feet, the conduit-pipeshould be about 39 lines; for an ajutage six lines diameter, and areservoir If) feet, the conduit-pipe must be2SA lines. There is noinconvenience in giving a conduit-pipe a gtcater diameter than the, U afe&vs ■