SPRING. 



principle of afcent in both is accordingly fuppofed to be the 

 fame with that of tlie afcent of liquids in capillary tubes, or 

 between contiguous planes, or in a tube filled with afhes ; all 

 which are now generally accounted for from the doarineot 

 attraftion. See River. , , , . 



Againa this kit theory-, M. Perrault and others have 

 urged feveral unanfwerablo objeaions. It fuppofes a va- 

 ricty of fubterranean pafTages and caverns, communicating 

 with the fea, and a comphcated apparatus of alembics, heat 

 and cold, &c. of the exiflence of which we have no fuf&cient 

 proof. Befidcs, the water that is fuppofed to afcend from 

 the depths of the fea, or from fubterranean canals proceed- 

 ing from it, through the porous parts of the earth, as it 

 rifes in capillary tubes, afcends to no great height, and in 

 much too fmall a quantity, to furnifh fprings with water, as 

 M. Perrault has fufficiently fliewn. And though the fand 

 and earth through which the water afcends may acquire fome 

 faline particles from it, they are neverthelefs incapable of 

 rendering it fo frefli as the water of our fountains is gene- 

 rally found to be. Not to add, that in procefs of time, the 

 fahne particles of which the water is deprived, either by 

 fubterranean diftiliation or filtration, muft clog and obllrudl 

 thofe canals and alembics by which it is fuppofed to be con- 

 veyed to our fprings, and the fea muft likewife gradually 

 lole a confiderable quantity of its fait. 



In fpeaking of the fituation of the earth, as connected 

 with the formation of fprings. Dr. Darwin has obferved, 

 that it confifts of ftrata, many of which were formed ori- 

 ginally beneath the fea. The mountains were afterwards 

 forced up by fubterraneous fires, as appears from the fiffures 

 in the rocks of which they confift, the quantity of volcanic 

 produftions all over the world, and the numerous remains of 

 craters of volcanoes in mountainous countries. Hence it is 

 contended, that the ftrata which compofe the fides of moun- 

 tains lie flanting downwards, and that one or two, or 

 more, of the external ftrata not reaching to the fummit 

 when the mountain was raifed up, the fecond or third 

 ftratuni, or a ftill more inferior one, is there espofed to day ; 

 this may be well reprefented, it is faid, by forcibly thrufting 

 a blunt inttrument through feveral fheets of paper, a bur 

 will Hand up with the lowefmoft ftieet ftanding higher in 

 the centre of it. On this uppernioft ftratum, which is 

 colder as it is more elevated, the dews are condenfed in large 

 quantities, and Aiding down, pafs under the firft or fecond 

 or third ftratum, which compofe the fides of the hill ; and 

 either form a morafs below, or a weeping rock, by oozing 

 out in numerous places, or many of thefe lefs currents meet- 

 ing together, burft out in a more copious rill. 



But that, as the fprings confift of the water which Aides 

 down between thofe incUned ftrata ; it is evident that, in 

 fome eminences of ground they are only to be met with on 

 one fide of the mountain ; and in other eminences of ground, 

 on all fides of it. In fearching for fprings, therefore, atten- 

 tion ftioiild be given to the inclination of the ftrata of that 

 part of the country, which may be often f'cn in marle-pits, 

 gravel-pits, or in hollow lanes. But they may in general be 

 found above any moift or morafly place, or valley ; the 

 moifture of which (hews that fprings exift in the ftrata on 

 that fide of the hill or mountain. And another obfervation 

 for the purpofe of detefting fprings, may, it is faid, be 

 made on mifty evenings ; as thofe parts of the ground where 

 the mift commences, are moift^r than thofe in their vicinity 

 on the fame level, and in confeqiience may generally, if they 

 are not hollow bafons, pofTefs fprings nearer the furface ; 

 for thefe moifter parts of the ground, having evaporated 

 more during the day, are become colder on their furfaces 

 than the drier ground-in their vicinity ; and in mifty evenings. 



which are at the fame time calm, the ftationary air over thefe 

 moift parts of the ground is alfo more loaded with the eva- 

 porated moifture ; and on both thefe accounts, thefe moifter 

 iituations are liable to (hew a condeifation of aerial vapour 

 fooner than other places on the fami. level. And there may be 

 other caufes of fprings in the nature of iiilly fituations, for as 

 mountains are colder in proportion to their height, ift, their 

 being in a manner infulated or cut off from the common heat 

 of the earth, which is always of 48", and perpetually coun- 

 terafts the efFefts of external cold beneath that degree, may 

 be one caufe. 2. From their furfaces being larger in pro- 

 portion to their folid contents, and hence their heat more 

 expeditiouAy carried away by the ever moving atmofphere. 

 3. The increafing rarity of the air as the mountain rifes. 

 All thofe bodies which conduft eleftricity well or ill, con- 

 duft the matter of heat likewife well or ill. Atmofpheric 

 air is a bad conduftor of eleftricity, and thence confines it 

 on the body where it is accumulated ; but when it is made 

 v.-ry rare, as in the eshaufted receiver, the eleftric aura pafTes 

 away immediately to any diftance. The fame circumftance 

 probably happens in refpeft to heat, which is thus kept by 

 the deiifcr air on the plains from efcaping, but is diffipated 

 on the hills, where the air is thinner. 4. As the currents 

 of air rife up the fides of mountains, they become mechani- 

 cally rarefied, the pre Aure of the incumbent column leffeniiig 

 as they afcend. Hence the cxpznding air abforbs heat from 

 the mountains as it afcends. 5. There is another, and per- 

 haps more powerful caufe, it is fufpefted, which may occa. 

 fion the greater cold on mountains, and in the higher parts 

 of tlie atmofphere, and which has not yet been attended to; 

 it is meant that the fluid matter of heat may probably gra- 

 vitate round the earth, and form an atmofphere, which may 

 diminilh or become rarer, as it recedes from the earth's fur- 

 face, in a greater proportion than the air dimini(hcs. And 

 the greater condenfation of moifture on the fummits of 

 hills has another caufe, which is the dafhing of moving 

 clouds againft them ; in mifty days this is often feen to have 

 great efFefts on plains, where an eminent tree, by obftruft- 

 ing the mift as it moves along, (hall have a much greater 

 quantity of moifture drop from its leaves, than falls at the 

 fame time on the ground in its vicinity. Hence it is con- 

 cluded, as fuggefted above, that the evening mift commences 

 fooner on them than in the vallies, but is feen earliir in the 

 fituations over the moifter places, if they are on the fame 

 level with the drier ones, exaftly as on the plains or vallies ; 

 and may therefore indicate the exiftence of Iprings, unlefs 

 thefe moifter places confift of hollow bafons, containing 

 water, which, if not attended to, may in all fituatii>ns de- 

 ceive the obferver. And further obfervations for detefting 

 fprings may be made in rimy mornings ; for as moift earth 

 is a belter conduftor of heat than dry earth, the rime 

 will fooner melt on thofe parts of the foil which are 

 kept moift by fprings under it than in other parts ; as the 

 common heat of the earth, which is 48"' in this country, 

 will fooner be condudled upwards in moid places to diffolve 

 the rime on the furface. On this account the rime is fre- 

 quently feen on frofty mornings, when the heat of the air is 

 not much above 32°, to lie an hour longer on dry cakes of 

 cow-dung, or on bridges, or planks of wood, than on the 

 common moift ground, as the latter much better condufts the 

 common heat of the earth to the incumbent rime .vhich is 

 in contaft with it. But as the heat of the common fprings 

 in this country is 48^, where they exift, the rime is fooner 

 diffolved than on the ftagnant moifture of bogs or moraC'es. 

 It is therefore concluded, that the common cold fprings are 

 thus formed on elevated grounds by the condenfed vapours, 

 and hence are ftronger when the nights are cold, after hot 



days 



