« FöregåendeFortsätt »
young ones is very good eating, for the sake of this hunt the beast
, but sometimes has a strong flavour and kill it with their poisoned arof a certain shrub, which is fup- rows. Of the skin they make refposed to be a species of mimosa. fels, in which they keep water and *The Hottentots are particularly other liquors.” fond of the marrow, and chiefly
An ACCOUNT of an ARTIFICIAL SPRING of WATER. By
ERASMUS DARWIN, M. D. F. R. S.
(From the Seventy-fifth Volume of the Philosophical Transactions.)
Onfident that every atom the water rose within two feet of
which may contribute to the top of the well. increase the treasury of useful know- Having observed that a very ledge, which you are so success- copious spring, called St. Alkmund's fully endeavouring to accumulate, well, rose out of the ground about will be agreeable and interesting to half a mile higher on the fame fide the Society, I send you an account of the Darwent, the level of which of an artificial spring of water, I knew by the height of the interwhich I produced last summer near vening wier to be about four or the fide of the river Darwent, in five feet above the ground about my Derby.
well; and having observed, that “ Near my house was an old the higher lands, at the distance of well, about one hundred yards from a mile or two behind these weils, the river, and about four yards consisted of red marl like that in deep, which had been many years the well, I concluded, that, if I difused on account of the 'badness thould bure through this itratum of of the water, which I fourd to marl, I might probably gain a wacontain much vitriolic acid, with, ter similar to that of Si, Alkmund's at the fame time, a Night Tulphu. well, and hoped that at the same reous shell and taste; but did not time it might rise above the surface carefully analyse it. The mouth of my old well to the level of St. of this well was about tour feet Alkmund's. above the surface of the river; and " With this intent a pump was 'the ground, through which it was first put down for the purpose of funk, contisted of a black, loose, more easily keeping dry the bottom moilt earth, which appeared to hare of the old well, and á hole about been very lately a morass, and is two and an half inches diameter now covered with houses built upon was then bored about thirteen yards 'pikes. At the bo tom was found a below the bottom of the well, will bed of red marl, and the tpring, some sand was brought by the auwhich was fo itrung is to give up ger. A wooden pipe, which was many hogsheads in a day, oozed previously cut in a conical form at from between the morals and the one end, and armed with an iron marl : it lay about eight feet be- ring at the other, was driven into neath the surface of the river, and tho top of this hole, and food up
about two yards from the bottom of rose about a foot above the top of the well, and being surrounded with the well in the leaden pipe; and, well rammed clay, the new water on bending the mouth of this pipe ascended in a small Arcam through to the level of the surface of the the wooden pipe.
ground, about two hogsheads of “ Our next operation was to water flowed from it in twenty-four build a wall of clay against the mo. hours, which had fimilar properrafly lides of the well, with a wall ties with the water of St. A'kof well-bricks internally, up to the mund's well, as on comparison both top of it. This completely itopped these waters curdled a solution of out every drop of the old water; foap in spirit of wine, and aboundand, on taking out the plug which ed with calcareous earth, which was had been put in the wooden pipe, copiously precipitated by a solution the new water in two or three days of fixed alkali; but the new water rose up to the top, and flowed over was found to pofless a greater abun. the edges of the well.
dance of it, together with nume“ Afterwards, to gratify my cu- roụs small bubbles of aerial acid or riofity in seeing how high the new
calcareous gas. spring would rise, and for the agree- " The new water has now flow. able purpose of procuring the wa- ed about twelve months, and, as ter at all times quite cold and fresh, far as I can judge, is already in. I directed a pipe of lead, about creased to almost double the quan. eight yards long, and three-quar- tity in a given timne ; and from the ters of an inch diameter, to be in. rude experiments I made, I think troduced through the wooden pipe it is now less replete with calcareous described above, into the stratum earth, approaching gradually to an of marl at the bottom of the well, exact correspondence with St. Alkso as to stand about three feet above mund's well, as it probably has its the surface of the ground. Near origin between the same itrata of the bottom of this leaden pipe was earth. sewed, between two leaden rings or “ As many mountains bear in. flanches, an inverted cone of ftiff contestable marks of their having leather, into which some wool was been forcibly raised up by some stuffed to stretch it out, so that, af- power beneath them ; and other ter having passed through the wood- mountains, and even islands, have en pipe, it might completely fill been lifted up by subterraneous up the perforation of the clay. An- fires in our own times, we may other leaden ring or flanch was fol. fafely reason on the same suppodered round the leaden pipe, about lition in respect to all other great two yards below the surface of the clevations of ground. Proots of ground, which, with some doubles these circumstances are to be seen of fannel placed under it, was on both fides of this part of the nailed on the top of the wooden country. Whoever will inspect, pipe, by which means the water with the eye of a philosopher, the was perfectly precluded from rising lime-mountain at Breedon, on the between the wooden and the leaden edge of Leicestershire, will not hepipes.
sitate a moment in pronouncing, * This being accomplished, the that it has been forcibly elevated bottom of the well remained quite by some power beneath it ; for it is dry, and the new water quickly of a conical form, with the apex cut off, and the strata, which com- “ And as the more elevated parts pose the central parts of it, and of a country are so much colder which are found nearly horizontal than the vallies, owing perhaps to in the plain, are raised almost per a concurrence of two or three pendicularly, and placed upon their causes, but particularly to the lefs edges, while those on each side de condensed state of the air upon cline like the surface of the hill; hills, which thence becomes a bete fo that this mountain may well be ter condutor of heat, as well as represented by a bur made by forc- of electricity, and permits it to ing a bodkin through several paral- escape the faiter; it is from the lel sheets of paper. At Router, or water condensed on these cold sure Eagle-fione, in the Peak, several faces of mountains, that our comlarge masses of grit-Itone are seen mon cold fprings have their origin; on the sides and bottom of the and which, fliding between two of mountain, which by their form the strata above described, descend evince from what parts of the sum till they find or make theinfelves an mit they were broken off at the outlet, and will in consequence rife time it was elevated ; and the nu. to a level with the part of the mcrous loose stones scattered about mountain where they originated. the plains in its vicinity, and half And hence, if by piercing the earth buried in the earth, mutt have been you gain a spring between the lethrown out by explotions, and prove cond and third, or third and fourth the volcanic origin of the moun- ftratum, it muit generally happen tain. Add to this the vall beds of that the water froin the loweit itratoad-stone or lava in many parts of tum will rise the highest, if conthis county, fo accurately describ- fined in pipes, because it comes ed, and fo well explained, by Mr. originally from a higher part of Whitehurit, in his Theory of the the country in its vicinity. Formation of the Earth.
" The increasing quantity of 6. Now as all great elevations of this new spring, and its increasing ground have been thus raised by purity, I 'luppose to be owing to fubterraneous fires, and in a long its continually diffolving a part of course of time their fummits have the carth it pafles through, and been worn away, it happens that hence making itself a wider chansome of the more interior Itrata of nel, and that through materials of the earth are exposed naked on the lefs folubility. Hence it is procops of mountains ; and that, in bable, that the older and stronger general, those strata, which lie up. fprings are generally the purer ; permost
, or nearest to the summit and that all iprings were originally of the mountain, are the lowest in loaded with the foluble impurities the contiguous plains. This will of the strata, through which they be readily conceived, if the bur, transuded. made by tbrusting a bodkin through " Since the above-related erpe. several parallel theets of paper, had riment was made, I have read with a part of its apex cut off by a pen- pleasure the ingenious account of knife, and is well explained by the King's wells at Sheerness, in Mr. Michell, in an ingenious pa. the latt volume of the Transactions, per on the Phænomena of Earth- by fir Thomes Hyde Page, in which quakes, published a few years ago the water rose three hundred fect in the Philosophical Transactions, above its source in the well; and have also been informed, that in above mentioned. And there is the town of Richmond, in Surrcy, reason to conclude, that if fimilar and at Inship near Preston, in Lan: experiments were made, artificial cathire, it is usual to bore for water springs, rifing above ground, might through a lower stratum of earth'to in inany places be thus produced at a certain depth; and that when it small expence, both for the comis found at both those places, it mon purposes of life, and for the rises to high as to overflow che fur. great improvement of lands by oc. face of the well: all these facts calionally watering thein." contribute to 'eitablish the theory
EXTRACT from the Rev. Mr. MORGAN'S OBSERVATIONS and
EXPERIMENTS on the LIGHT of BODIES in a STATE of COMBUSTION.
[From the fame Publication.]
'HE discussion which I now the expresfion) be the last to quit
here have reRoyal Society is nothing more than course to a familiar fact, which is a series of facts, and of conclufions analogous to this, and will illuirate which seem to flow from thoss facts, it. If a mixture, contiiting of and from an attention to the follow- equal parts of water, of 1pirits of ing data.
wine, and of other more fixed bo. “ I. That light is a body, and, dies, be placed over a fire; the like all other bodies, subject to the first influence of that heat, to which laws of attraction.
all the ingredients are alike exposed, “ 11. That light is an heteroge- will carry off the spirits of wine neous body, and that the fame at. only. The next will carry off the trative power operates with dif- fpirits of wine blended with par. ferent degrees of force on its dif- ticles of water. A full greater de
gree of heat will blend with the " Ill. That the light which vapour which escapes a part of the escapes from combustibles when de- more fixed bodies, till at length composed by heat, or by any other what evaporates will be a mixture means, was, previously to its escape, of all the ingredients which were a component part of those sub- at first exposed to the fire. In like Itances.
manner, when the surface of a ". It is an obvious conclusion combuttible is in a state of decomfrom these data, that when the ate polition, those parts which are the tractive force, by which the several least fixed, or which are united to rays of light are attached to a it with the least force, will be sepabody, is weakened, some of those rated first. Amongit these the inrays will escape sooner than others. digo rays of light will make the Those which are united with the earliest appearance. By increasing leaft degree of power will escape firk, the heat we shall inix the violet and those which adhere to it most with the indigo. By increasing it Itrongly will (if I may be allowed still more we all add the blue and
the green to the mixture, till at most beautifully coloured with the length we reach that intenfity of violet and indigo rays. To the preheat which will caute all the rays to ceding instance of a common cane escape at the same intant, and make dle many
faes may be added, which the fanne of a combuitible perfectly speak a similar language. If ful. white. It is not my present design phur or æther is burned, or any of to thew why the most refrangible those combustibles whose vapour is rays are the first which escape from kindled in a small degree of heat, a a burning body, but to enumerate blue flame will appear, which, if the several facts which seem to examined by the prism, will be Mhew, that such a general law takes found to consist of the violet, the place in combustion ; and that the indigo, the blue, and sometimes various colours of bodies in this small quantity of the green rays. ftate are uniformly regulated by The beit mode, however, of fhew. that decrease of attractive force now ing the escape of some rays by that deferibed.
degree of heat which will not fe“ By examining the flame of a parate others till increased, is the common candle we may observe, following. Give a piece of brown that its lowest extremities, or the paper a spherical form, by preffing part in which the black colour of it upon any hard globular subit ance. the wick terminates, discharges the Gradually bring the paper, thus least heat; and that, as the vertex formed, to that distance froin the of the flame is approached, a succandle at which it will begin to cessive order, of parts is passed take fire. In this case a beautiful throngh, in which the lowest is blue flame may be seen, hanging as continually adding to the beat of it were by the paper till a hole is what is just above it, till we come made in it, when the flame, owing to the top of the flame, near which to the increased action of the air all the heat is collected into a focus. upon all parts of it, becomes white, At the loweit extremity, however, though the edges still continue of where the heat is incontiderable, a a blue or violet colour. As a conblue colour may be always observ, firmation of what I have concluded ed; and from this appearance, from the preceding facts, it may be amongst others, it may, I think, observed, that the very fame be safely concluded, that the blue which, when exposed to a certain rays are some of those which escape degree of heat, emitted the most from combustibles in an early pe- refrangible rays only, will, if exriod of their decompofition; and posed to a greater degree of heat, that if the decompolition could be emit such as are less refrangible. examined in a period still more The flames of fulphur, spirits of carly, the colour of their flame wine, &c. when fuddenly exposed would be violet. By an a priori to the heat of a reverberatory, deduction of this kind, I was led change their blue appearance for to watch the appearances of a can, that which is perfectly white. But dle more attentively; whence I to gain a more striking diver: ty of found that to ihe external boundary this fact, I adopted Mr. Melvill's of a common candle is annexed a mode of examining bodies whilft on .filament of light, which, if proper fire. I darkened my room, and ca'e be taken to prevent the escape placed between my eye and the of too much fmoke, will appear combustible a sheet of paste-board,