SPRING. 



days in fpring, tlian even in the wet days of winter. For 

 the warm atmofphere durinir the day has did'olvcd much more 

 water than it can lupport in lolution during the cold of the 

 night, which is thus depofited in large quantities on the hills, 

 and yet fo gradually, as to foak. in between the llrata of 

 them, rather than to Aide oft over the furfaces, like fhowers 

 of rain. The common heat of the internal parts of the 

 earth is afcertained by fprings which arife from the ilrata of 

 earth too deep to be affefted by the heat of the fummer, or 

 the frofts of winter. Thofe in this country, as has been 

 feen, are of 48° of heat, thofe about Philadelphia were 

 faid by Dr. Franklin to be jz^. Whether this variation is to 

 be accounted for by the difference of the fun's heat in that 

 country, according to the ingenious theory of Mr. Kirwan, 

 or to the vicinity of fubterranean fires, is not yet, it is 

 thought, decided. And in the winter months, the rife of 

 fprings may be detefted in moid ditches by the prefence of 

 aquatic plants, as of the water-crefs, water-parfnip, brook- 

 lime, &c.; as in thofe ditches which become dry in fummer 

 thefe plants do not exilt ; and when thofe ditches with 

 fprings in them are nearly dry, it may be difcovered which 

 way the current has formerly defcended, by the direftion of 

 the points of the leaves of aquatic plant?, as certainly as 

 by a level ; an obfervation which was learnt from Mr. Brind- 

 ley, the great canal conduftor of Stafforddiire. 



The proper application of thefe principles may lead to 

 many ufeful conclufions, both in refpeft to agriculture and 

 rural economy, and is a fort of knowledge which thofe en- 

 gaged in the providing of water for wells or pits ihould 

 be well acquainted with. See Draining, Water, and 

 Well. 



For the method of preventing or remedying the injury 

 done to land by fprings, &c. fee Spnii^G-Draining. 



Springs, D\jft:rent Sorts of. Springs are either fuch as 

 run continually, called perennial ; or fuch as run only for 

 a time, and at certain fealons of the year, and therefore 

 called temporary fprings. Others, again, are called inter- 

 mitting fprings, bccaufe they flow and then Hop, and flow 

 and flop again ; and reciprocating fprings, whofe waters rife 

 and fall, or flow and ebb, by regular intervals, which are 

 alfo called "ebbing and flowing wells." In order to ac- 

 count for thefe diderences in fprings, let A B C D E 

 (Plate XV. Hydraulics, Jig. 7.) rcprefent the declivity of a 

 hill, along which the rain defcends ; palling through the 

 fiflures or channels B F, C G, D H, and L K, into the 

 cavity or refervoir F G H Iv M I ; from this cavity let there 

 be a narrow drain or duft K E, which difcharges the water at 

 E. As the capacity of the refervoir is fuppoled to be large 

 in proportion to that of the drain, it will furnifh a conftant 

 fupply of water to the fpring at E. But if the refervoir 

 F G H K M I be fmall, and the drain large, the water 

 contained in the former, unlcfs it is fupplied by rain, will 

 be wholly difcharged by the latter, and the fpring will be- 

 come dry ; and fo it will continue, even though it rains, till 

 the water has had time to penetrate through tlie earth, or to 

 pafs through the channels into the refervoir ; and the time 

 necefl'ary for furniftiing a new fupply to the drain K E, will 

 depend on the fize of the fifl^ure, the nature of the foil, and 

 the depth of the cavity with which it communicates. Hence 

 it may happen, that the fpring at E may remani dry for a 

 ccnfiderable time, and even vvhilll it rains ; but when the 

 vrater has found its way into the cavity of the hill, the fpring 

 will begin to run. Springs of this kind, it is evident, may 

 be dry in wet weather, efpecially if the duiil K E is not 

 exaclly level with the bottcjm of the cavity in the hill, and 

 difcharge water in dry weather ; and the intermiflion of the 

 fpring mav continue for Icvcral days. But if we fuppofe 



Vol. X'XXIII. 



X O P to reprefent another cavity, iupplied with water by 

 the channel N O, as well as by fiilures and clcils in the 

 rock, and by the draining of tlic adjacent earth ; and another 

 channel S T V, communicating with the bottom of it at 

 S, afcending to T, and terminating on the furface at V, in 

 the form of 3. ftphon (which fee) ; this difpofition of the 

 internal cavities of the earth, which we may reafonably fup- 

 pofe that nature has formed in a variety of places, will ferve 

 to explain the principle of reciprocating fprings. For it is 

 plain that the cavity X O P muft be fupplied with water to 

 the height Q P T, before it can pafs over the bend of the 

 channel at T, and then it will flow through the longer 

 leg of the fiphon T V, and be difcharged at the end V, 

 which is lower than S. Now if the channel S T V be 

 conliderably larger than N O, by which the water is 

 principally conveyed into the refervoir X O P, the refer- 

 voir will be emptied of its water by the fiphon ; and when 

 the water defcends below its orifice S, the air will drive 

 the remaining water out of the crooked channel S T V, 

 and the fpring will ceafeto flow. But in time the water Ir 

 the refervoir will again rile to the height O P T, and be 

 difcharged at V, as before. It is cafy to conceive, that tlie 

 diameters of the channels N O and S T V may be fo pro- 

 portioned to one another, as to afford an intermiflion and 

 renewal of the fpring V at regular intervals. Thus, if N O 

 c::mmunicates with a well fupplied by the tide, during the 

 time of flow, the quantity of water conveyed by it into the 

 cavity X O P, may be iufficient to fill it up to Q P T ; 

 and S T V may be of fuch a fize as to empty it, during the 

 time of ebb. It is eafy to apply this realoning to more 

 complicated cafes, where feveral refervoirs and fiphons, com- 

 municating with each other, may fupply fprings, with cir- 

 cumftances of greater variety. See Mufchcnbrocck's In- 

 trod. ad Phil. Nat. torn. ii. p. loio. Defag. Ex. Phil, 

 vol. ii. p. 173, &c. 



We fhall here obferve, that Defaguliers calls thofe reci- 

 procating fprings which flow condantly, but with a fl;ream 

 fubjeft to increafe and decreafe ; and thus he diltinguiflies 

 them from intermitting fprings, whicii flow or ftop alter- 

 nately. 



It is faid, that in the dioccfeof Paderborn,in Wcftphalia, 

 there is a fpring which difappears twice in twenty-four 

 hours, and always returns at the end of fix hours with a 

 great noife, and with fo much force, as to turn three mills 

 not far from its fource. It is called the lolder-born, or 

 boilterous fpring. Phil. Tranf. N° 7. p. 127. 



There are many fprings of an extraordinary nature in our 

 own country, which it is needlefs to recite, as they are ex- 

 plicable by the general principles already illuftrated. 



Springs are farther divided into oozing or weeping fprings, 

 where the water gently trickles through the pores of the 

 land ; pipe fprings, where they appear in a fingle rill ; and 

 wa// fprings, where the w.iter illues, as it were, through 

 the joints of a wall. But befides thefe, fprings have many 

 other local names, which ferve to dillinguilh them in their 

 particular fituations, where they break out in grounds. See 

 SpniSG-Draining. 



SriiiNO.s, Burning, or Boiling. The burning fpring near 

 Grenoble, in Dauphine, is famous. St. Augulline (peaks of 

 it as extinguifliing lamps which are lighted, and lighting 

 thofe which arc exlind. But it is now cold, like others ; 

 only near it is a fpot of ground, which Hill emits a light 

 flame ; over whicli fonie imagine it might auciently have 

 palled. Augull. de Civ. Dei, lib. xxi. cap. 7, and II, 

 Mem. Acad. Infcript. torn. ix. p. 565. Mem. Acad. Scien, 

 an. 1699, p. 26. 



At Bofeley, near Wenlock, in Shroplhirc, there is a fa- 

 4 H mom 



