FOU
(87)
FOU
Or thus : Suppofe the Vertical Tube A B, Fig. 19. thro* which the Water arifes, to be ftop'd a-top, as in A ■ and inftead of Pipes, or Jets, let it be only perforated with lit- tle Holes ail around, or only half, its Surface. Then will the Water fpin forth in all Directions thro' the little Aper- tures, and to a Diflance proportional to the Height of the fall of the Water. -
And hence if the Tube A B be fuppos'd the Height of a Man, and be furnifh'd with an Epiftomium, or Cock at C : Upon opening the Cock, the Spectators, dreaming of no fuch Matter, will be cover'd with a Shower.
It muft be here obferv'd, that the Diameters of the A- pertures, by which the Water is emitted, muft be confi- derably lefs than thofe of the Tubes in which the Water is brought; left the Refinance of the Air, and other Impedi- ments, fpecify'd under Fluid, break the Force of the Wa- ter. — —
A Fountain flaying by the Draught of the Breath.
Suppofe A B, Fig. 10. a Glafs or Metal Sphere ; wherein is fitted a Tube, C D, having a little Orifice in C, and reaching almoft to D, the Bottom of the Sphere. If now the Air be fuck'd out of the Tube C D, and the Orifice C be immediately immerg'd under cold Water ; the Water will afcend thro' the Tube into the Sphere.
Thus proceeding, by repeated Exfuflions, till the Veffel be above half full of Water ; and then applying the Mouth to C, and blowing Air into the Tube; upon removing the Mouth, the Water will fpout forth.
Or, if the Sphere be put in hot Water; the Air being thereby rarify'd, will make the Water fpout as before.
This kind of Fountain is call'd Pila Heronis, or Hero's Ball, from the Name of its Inventor.
A Fountain, the Stream ivbereof raifes, and flays a Brafs Sail.
Provide a hollow Brafs Ball A, Fig. zl. made of a thin Plate, that its Weight may not be too great for the Force of the Water. Let the Tube B C, through which the Wa- ter rifes, be exactly perpendicular to the Horizon.
Then, the Ball being laid in the Bottom of the Cup, or Bafon B ; will be taken up in the Stream, and fuftain'd at a confiderable Height, as A ; alternately vibrating, or playing up and down.
Hence, as the Figure of the Ball contributes nothing to 1 its reciprocal Rife, and Fall : Any other Body, not too hea- vy, may be fubftituted in lieu thereof; e. gr. a Bird with its Wings ftretch'd forth.
But, note, that as 'tis neceffary the Globe, when on the Defcent, fhou'd keep the fame precife Perpendicular, wherein it rofe (fince otherwife it wou'd mils the Stream, and fall downright) ; fuch a Fountain Ihou'd only be play'd in a Place free from Wind.
A Fountain which fpouts the Water in manner of a Shower.
To the Tube wherein the Water is to rife, fit a Spherical, or Lenticular Head, A B, Fig. 22. made of a Plate of Me- tal, and perforated a-top, with a great Number of little Holes.
The Water rifing with Vehemence towards A B, will be there divided into innumerable little Threads, and after- wards broke, and difperfed into the fineft Drops. — —
A Fountain -which fprcads the Water in form of a Cloth.
To the Tube A B, Fig. 23. folder two Spherical Segments C, and D, almoft touching each other ; with a Screw E, to contrail, or amplify the Interftice or Chink at Pleafure.
Others chufe to make a fmooth, even Nitch, in a Sphe- rical, or Lenticular Head, fitted upon the Tube.
The Water fpouting thro' the Chink, or Nitch, will ex- ■ pand it felf in manner of a Cloth.
Fountains •wherein the Wated fpouts out of the Figures of Men and other Animals.
Since Water may be deriv'd or convey'd by Tubes in
' | any Situation ; and always retains the Direction of the A-
perture: All here requir'd, is to inclofe Tubes within the
Figures of Men, or other Animals, having their Orifices in
thole Parts whence the Water is to fpout forth.
From the Principles hitherto laid down, it will be very eafy to deduce whatever relates to the Furniture of Foun- tains, and the various Forms Water may be put into by their means : All depending on the Magnitude, Figure, and Direction of the Ajutages, or Apertures. ;
A Fountain, -which -when it has done fpouting, may li turn'd like an Hour-gtafs.
Provide two Veffels, L M, and N O, Pig'. 24. to be fo' ■ much the bigger as the Fountain is to play the longer ■ and plac'd at fo much the greater Diflance from each other' P N' as the Water is defir'd to fpout the higher. Let B A C be a crooked Tube, furnifh'd in C with a Cock ; and FED an other crooked Tube, furnifh'd with a Cock in D. In I, and K. are to be other leffer Tubes, open at both Ends, and reaching near to the Bottoms of the Veffels N O, and L M : To which the Tubes Q_R, and S T are likewife to reach. If, now, the Veffel L M be fill'd with Water ; it will def- cend thro' the Tube B A, and upon opening the Cock C, will fpout up near to the Height of K : And, after its Fall again, will fink thro' the little Tube I, into the Veffel N O, and expell the Air thro' the Tube 0_O. At length, when all the Water is emptied out of the Veffel L M ; by turning the Machine upfide down, the Veffel N O will be the Rcfervoir, and make the Water fpout up through the Cock D. ' '■:. \
Hence, if the Veffels L M, and N O contain juft as much Water as will be fpouted up in an Hour's time ; we mall have a fpouting Glcpfydra, or Water Clock, which may be graduated or divided into Quarters, Minutes, iSc. as fhewn under the Article Clepsydra.
A Fountain that begins to play upon the lighting of Can- dles, and ceafes as they go out.
Provide two Cylindrical Veffels, A B, and C D, Pig. 2;. Connect them by Tubes, open at both Ends, K L, B F, Sic. fo that the Air may defcend out of the higher, into the lower. To the Tubes folder Cindlefticks, H, iSc. And to the hollow Cover of the lower Veffel, C F, fit a little Tube, or Jet F E, furnifh'd with a Cock G, and reaching almoft to the Bottom of the Veffels. In G let there be an Aper- ture, furnifh'd with a Screw, whereby Water may be pour'd into CD.
Then, upon lighting the Candles H, i$c. the Air in the contiguous Tubes becoming rarify'd thereby; the Water will begin to fpout thro' E F.
By the fame Contrivance may a Statue be made to fried Tears upon the refence of the Sun, or the lighting of a Candle, £fV. All here requir'd, being to lay Tubes from the Cavity wherein the Air is rarify'd, ^to fome other Cavities near the Eyes, and full of Water. — —
Fountain, with regard to Architecture, is ah Affemblagffl of Mafonry, Sculpture, &c. either for the Decoration, or Con- veniency of a City, Garden, or the like.
Fountains acquire various Denominations, according to their Form, and Situation; as,
Spring Fountain, a kind of plain Spout, or Stream of Water, iffuing out of a Stone, or Hole in a Wall, without any Decoration.
Such is the Fountain of Trevi at Rome.
Coverd Fountain, a kind of Pavillion, built of Stone; ei- ther Infulate, and fquare; or round; or Multilateral; or back'd: And that, either with a Prefecture, or Indenture : Incloting a Refervoir, and fpouting, or darting forth the Water thereof thro' one or more Cocks ; in the Middle of a Street, Square, Garden, Court, or the like. Such is that in Lincohn-Iun, London.
Open Fountain, is any fpouting Fountain, with a Bafon, Cup, and other Ornaments; all open : As is frequent in our Gardens, and the Vineyards at Rome.
Spouting Fountain, or Jet d'Ean, is any Fountain^ whofe Water is darted forth impetuoufly thro' one, or more Jets, or Adjutages, and returns in Rain, Nets, Folds, or the like. See Jet d'Eau.
"Bafon Fountain, is that with only a fimple Bafon, of any Figure whatever; in the Middle whereof is a Jet, or Spout, or perhaps a Statue ; or even a Group of Figures: As in the Court of Buckingham Houfe.
Cup Fountain, is that which befide a Bafon, has like- wife a Cup of one fingle piece of Stone, or Marble, fup- ported on a Shaft, or Pedeftal, and receiving a Jet, or Spour, rifing out of the Middle thereof. As the Fountain in the Court of the Vatican ; the Cup whereof is of Gra- nate, and antique ; being brought from the Baths of "Titus at Rome.
'pyramidal Fountain, that form'd of feveral Bafons, or Cups, rang'd in Stories over each other, and dimini/hing all the way ; being fupported by a hollow Stem, or Shaft.
As the Fountain of Monte-tDragone at Frefcati : Or elfe fupported by Figures, Fifhes, or Confbles ; the Water whereof in its Fall makes Nets in divers Stories, and repre- fents a kind of Water Pyramid : As that at the Head of ths Cafcades at Verfailles.
Statuary Fountain, that which being open and infu-
lated
