S P R
S P R
quantity of motion equal to the former, aswMx-, wi]
clofe the fame fpring, and be wholly confumed thereby. 9 . But a quantity of motion, lefs or greater than M V, in any given ratio, may clofe the fame fpring, and be wholly confumed in clofmg it ; and the time fpent in clof- ing the fpring will be refpe&ively lefs or greater, in the fame given ratio.
C a P L
10". The initial vis viva, or MV% is equal to
- ■ ;
- . 3 *i
and zaM=?L.
n°. The initial vis viva is as the rectangle under the
ftrength and length of the fpring ; that is M V V is as P L.
P 12°. If — be given, the initial vis viva is as P% or as
13°. If the vis viva MV a bend a fpring through its whole length, and be confumed in clofmg it; any other w'j mm,
equal to the former, as n n M x will clofe the fame
fpring) and be confumed thereby.
14. . But the time of clofmg the fpring by the vis viva
n n M x — , will be to the time of clofmg it by the vis
viva M V z , as » to i .
15 . If the vis viva M V 3 be wholly confumed in clofing a fpring of the ftrength P, and length L ; then the vis viva »»MV 2 will be fufficient to clofe, i\ either a fpring of the ftrength n n P, and length L. 2 3 . Or a fpring of the ftrength n P, and length n L. 3 . Or of the ftrength P, and length n n L. 4 . Or if n be a whole number, the number n n offerings, each of the ftrength P, and length L, one after another. We may add, that it appears from hence that the number of fimilar and equal fprings a given body in motion can wholly clofe, is always proportional to the fquares of the velocity of that body. And it is from this principle that the chief argument, to prove the force of a body in motion to be as the fquare of its velocity, is de- duced. See Force, Appendix.
The theorem abovementioned, and its corollaries, will hold equally, if the fpring be fuppofed to have been at firft bent through a certain fpace, and by unbending itfelf, to pafs up- on a body at reft, and thereby to drive that body before it, during the time of its expanfion : only V, inftead of being the initial velocity with which the body (truck the fpring, will now be the final velocity, with which the body parts from the fpring when totally expanded. It is alfo to be obferved, that the theorem, effr. will hold equally good, if the fpring, inftead of being prefled inward, be drawn outwards by the action of the body. The like* may be faid, if the fpring be fuppofed to have been already' drawn outwards to a certain length, and in reftoring itfelf draw the body after it. And laftly, the theorem extends to fprings of any form whatever, provided L be the greateft length it can be extended to from its natural fituation, and P the force which will confine it to the length. See Phil. Tranf. N"472. feci:. 10.
Spring, in natural hiftory. Nothing is more certain, than that Come fprings wholly owe their origin to rains, though this is not the cafe with others. Thofe intermitting //>W»g-j, which flow very largely after great rains, and then are gra- dually dried up, are owing wholly and entirely to rains ; but thofe are not the only ones, but fome of the perennial fprings, which run in fummer as well as winter, and in dry as-wellaswet feaforis, are owing alfo to rains or vapours of a like kind ; thus thofe fprings, found at the tops of mountains, feem to be owing to the thick mifts which we every day fee hanging about the top of thofe moun- tains.
Though fome fprings are thus evidently owing to rain and vapours, yet others are plainly of fome very different origin. The temporary fprings, or irregular fountains we find in many parts of the world, cannot come from rains or dews, much lefs can thofe regular periodic fountains, of the nature of the Zirchnitzer fea in Carniola, and the fountain of Loire in France, and that of Lambfbournein England : and it is yet lefs poflible, that fuch vaft perennial fprings, as thofe ofWellow bridge in our kingdom, and of the Sorgue in France, can come from rains ; for all the water that falls in the whole country about thefe places, in rains and dews, is not nearly fo much as that which ifities from them. Plot, de Origin. Font.
It is faid b that in the diocefe of Paderborn, in- Weftphalia, 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 bolder-born, or boi- fkcrous Jpring. — [ b Philof. Tranf. N° 7. p. 127.]
Burning, or Boiling Springs. The burning fpring near Gre- noble in Dauphuie is famous : St. Auguftin (peaks of it as extinguiftiing lamps which are lighted, and lighting thofe which are extinft c . But it is now cold like others ; only near it is a fpot of ground, which ft ill emits a light flame ; over which fome imagine it might antiently have palled d . Suppl. Vol. II.
--[ c Augufl. de Civ. Dei, lib. 21. cap. 7. & lr . Merrj. Acad. Inlcipt., Tom. 9. p. 565. d Mem. Acad, bcien. An. 1099. P- 26.]
AtEofely, near Wenlock in Shropftnre, there is a famous boiling well, which was difcovered, in June 1711, by an uncommon noife in the night, fo great, that it awakened feveral people, who being defirous to find what it was ow- ing to, at length found a boggy place under a little hill, not far from the Severn; and perceiving a great fhakino- of the earth, and a little boiling up of water through the grafs, they took a fpade, and digging up fome part of the earth, the water flew to a great height, and was fet on fire by a candle. This water was for fome time afterwards conftantly found to take fire, and burn like fpirit of wine ; and after it was fet on fire, it would boil the water in a veffel fooner than any artificial fire, and yet the fpring itfelf was as cold as any whatever. Phil. Tranf. N° 334. This well was at length loft for many years, and not re- covered till May 1746, when by a rumbling noife under ground, like to what the former well made, it was bit upon again, though in a lower fttuation, and thirty yards nearer the river.
The well is four or five feet deep, and fix or feven wide ; within that is another lefs hole of like depth, dug in the clay, in the bottom whereof is placed a cylindric earthen veflel, of about four or five inches diameter at the mouth, having the bottom taken off, and the fides well fixed in the clay, rammed clofe about it. Within the pot is a brown water, thick as puddle, continually forced up by a violent motion, beyond that of boiling water, and a rumbling hol- low noife, riling and falling by fits five or fix inches. It may be fired by a candle at a quarter of a yard diftance ; and it darts and flafhes in a violent manner, about half a yard high. It has been left burning forty eight hours, with- out any fenfible diminution. It may be extinguifhed by putting a wet mop upon it, which muft be kept there a fmall time. On the removal of the mop there fucceeds a fulphureous fmoke, lafting about a minute, and yet the water is very cold to the touch. Phil. Tranf. N 3 482. fedt. 6.
Lancar'tm Spring. See the article Lancarim.
SpRiNC-ar&sr, in a watch, that part in the middle of the fpring-box, about which the fpring is wound or turned, and to which it is hooked at one end.
Spring-^, in a watch, the cylindrical cafe, or frame, that contains within it the fpring of the watch.
SPRINGER, in ichthyology, a name given by authors to' the grampus, or area.
SPRINGES, {Cycl.) a fort of horfehair noofes, made fo as to run very eafy, and planted in the places where birds run irt fome particular path, to take them as they pafs. Thofe birds that frequent the waters, or love to paddle and feed in wet and plafhy places, are the moft eafily taken by thefe fnares.
The fportfmen who would ufe them to advantage, muft firft: carefully fearch out the haunts and places where the fowls come in flocks, or in couples, and feed in the morning and evening hours. The furrows and water-tracks in thefe places are principally to be regarded ; and wherever the fe- veral furrows, or water-courfes, meet in one, and after- wards divide into feveral others, thefe places are to be re- marked above the reft : the places which have moft: marks of the birds feet, give alfo the fureft of all proofs, that they are well frequented. When thefe places are found, there ftiould be placed a number of fmall and fhort fticks crofs- v/ife overthwart all the other paftages, one ftick being placed about half an inch from another, and making together a kind of fence, guarding every way, except that one through which it is intended the fowls ftiould pafs. This being done, a good ftiff ftick is to be provided, cut flat on each fide; both ends of this ftick are to be planted under water, (o that the upper part of the flat fide may only be upon a level with the furface ; then a bow is to be made of a hazel, or willow, in the form of a pear, broad and round at one end, and narrow at the other, and at leaft a foot long, and five or fix inches wide ; at the narrow end of this there is to be a nick or dent. Then a ftiff* young grown plant of hazel, elm, or withy, is to be chofen, being bufhy and clear, and without knots, three or four inches about at the bottom, and about an inch at the top. Having made the bottom end of this fharp, at the top of it there muft; be faftened a very ftrong loop, made of about an hundred horfehairs, platted very faft together with ftrong packthread, and made to flip any way with great eafe. This noofe or loop ftiould be juft of the dimenfions of the pear-fafliioned loop before mentioned. Then hard by this loop, and within an Inch of the end of the plant, there is to be faftened with ftrong horfehair a broad and thin trigger, made fharp at both ends. Then the bigger fharp end of the plant being made faft in the ground, juft by the edge of the water; the ftnaller end, with the loop and the trigger, muft be brought down juft to the firft bridge ; and the pear-fafhioned hoop being fet upon the bridge, one end of the trigger muft be
I fet upon the nick in the hoop, and the other end on the
I 3 D d d nick
