believing that the hero of this story was a reality," and Sir Francis Palgrave roundly asserts that "the 'monstrous giant' who guarded the marsh was in truth no other than the tyrannical lord of the manor, who attempted to keep his copyholders out of the common field, Tylney Smeeth; but who was driven away with his retainers by the prowess of Tom armed only with his axle-tree and cart wheel." But here the mention of "copyholders" seems to conflict with "the reign before William the Conqueror," or any anterior date.

The solar myth explanation is, that Hikifricke, driving along his cart, is another form of the sun-god, a wheel and its axle being the symbols of the sun and its rays. Ages ago the boundaries of the Smeeth would be encroached upon by the original lord of the soil, the waters, which the sun, otherwise Tom Hikifricke, with his piercing rays and resplendent beams, likened to the axle and wheel, would eventually drive to the verge of the common.

The multiform action of the sun naturally makes it a possible symbol, or root-idea for almost any figure in history, or any phenomenon in nature; the cap will always fit when the head can be manipulated.

In any case this quaint old history of the Marshland giant-killer offers an interesting problem to students of folklore, and is in itself a notable piece of ancient English story-telling.

Tom Hickathrift has now and then figured in modern collections of old tales, notably in volume i. of Gammer Gurton's Famous Histories, edited by Ambrose Merton, F.S.A., in the earlier half of this century, and in the dainty Banbury Cross Series, issued by Messrs. J. M. Dent & Co., of Aldine House, for whom Miss Grace Rhys has prepared an exquisite little volume entitled Fairy Gifts and Tom Hickathrift, just published.

JAMES HOOPER.

49

FRO

ATMOSPHERIC HEAT.

ROM time immemorial an impression has prevailed that in the interior of our earth there is a vast reservoir of intense heatthat the beautiful surface on which we dwell may be only a cooled portion, a comparatively thin crust, covering over an inward molten

mass.

One reason assigned for this conjecture is, that as we descend in mines the temperature of the air is found to increase in a fixed ratio, which may be roughly or approximately estimated at about one degree for every 100 feet of direct descent. But this alleged proof, when examined, fails to confirm the conjecture; for everywhere, all over the surface of the earth, the same result is experienced. This could not be the case, because it implies that everywhere the molten mass or reservoir of heat is situated at an equal distance from the shaft or pit of descent, and that the intervening stratum of earth allows the travelling heat to permeate in exactly the same measure. Moreover, the practical workers in mines do not accept the conjecture as even probable, because at fresh excavations, however deep in the mine, the earth dug into and excavated has no feeling of being heated any more than the earth dug out at the surface of the pit. The difference of temperature exists only in the passages and shafts where the air from the earth's surface is freely admitted. Many external surroundings, such as the position of air shafts, or the distance. from the main direct shaft, or the windings of the passages, or the heat from lamps and from the working blasts or explosions, will modify the actual temperature at any given depth, both as to time and degree; but, making all allowance for these accidental or extraneous causes of increased or diminished heat in the passages or workings of the mines, it is found that there exists in varying rates a positive fixed amount of atmospheric temperature which, as before mentioned, may be roughly or approximately taken at about one degree for every 100 feet of direct descent. Thus the barometer and thermometer coincide exactly for every rise of one-tenth of an inch in the barometer there will be a rise of one degree in the VOL. CCLXXX. NO. 1981.

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thermometer. It is the same with respect to the atmosphere above the earth's surface or sea-level; for every fall in the barometer as a mountain is ascended there will be a fall in the thermometer. Excluding all external causes of increase or decrease of heat from the period of the year, the time of day, or the absence or presence of sunshine, wind, or moisture, it will be found that there is a fixed invariable temperature in the very atmosphere itself inherently, when surrounding influences are removed or taken into account in any reckoning. Precisely the same result happens above as below the surface of the earth-the barometer and thermometer rise and fall together.

The writer has long known and closely observed and considered these results; and after much experiment and inquiry in research of the truth he has arrived at the conclusion that every volume of atmosphere has inherently in itself its own proportion of heat atoms -whether by absorption, or in solution, or simply in contact by attraction, or by vibration, he is unable to prove or even conjecture. Of course, the sun's rays permeating the air, or any other cause of external increase or decrease of heat, will, for the time being, affect the atmospheric temperature in adding to or diminishing from its possession of heat; but such additions are entirely irrespective of the inherent amount of heat which the atmosphere always contains, which may be termed its own proper measure, irrespective of climate, or position, or external influences, but always the same, being in exact proportion to the density.

If at 2,000 feet below the surface of the earth the thermometer registers, say, 75 degrees, or if at 2,000 feet above the sea-level the thermometer registers 35 degrees (the mean being taken as 55 degrees), then the barometer will stand at 32 inches or 28 inches, the mean being taken as 30 inches. I hope that the readers of this article will not consider that I am presuming to state, as a scientific man of experience, that these things are so; I am only a humble learner and inquirer, putting forth my own observation and experience in the hope of drawing attention to facts which I feel to be of importance, because I believe that many lives may have been lost through its not being known or understood that atmospheric heat is in proportion to atmospheric density.

For example, sixty years ago, before lucifer matches were in such common use, there was a little instrument I had lent to me by a friend, resembling a boy's pop-gun, with a small brass tube about twothirds of an inch in diameter, closely fitted with a steel piston. The lower end of the tube was not open. A small piece of prepared tinder

or combustible substance being placed in a little cup at the lower end of the piston became ignited and used for a match on the piston being forced quickly home. The air, being thus reduced, perhaps to onetenth of its former volume, contained so much heat condensed as to ignite the tinder. Probably some accidents have occurred in exploding mines, or blasting rocks, or even loading guns through the bore not admitting any escape of the condensed air, and so by the heat evolved igniting the powder charge prematurely.

In experiments which have of late years been made to compress and condense the atmosphere great heat is evolved; so much so that the iron vessels used have to be cooled by cold water being poured upon them. On the compression of any gas separately such heat is not thrown off.

I have made many particular inquiries with reference to the heat of mines, and have ascertained beyond all doubt that when fresh seams are opened, or adits and drifts formed, the earth, coal, or mineral indicates no warmth whatever from any internal source: the warmth experienced is confined to passages or shafts where the air let in from the earth's surface circulates. Working miners smile at the idea of internal heat. In an extensive coal mine twelve miles from where I reside there is a shaft of one direct descent 575 yards, or 1,725 feet, in depth; the temperature, taken only casually, and not with scientific accuracy, is 75 degrees Fahrenheit. Some years since the deepest coal mine in England, near Manchester, was 2,151 feet, and the temperature 75 degrees constant. That mine is now worked at a depth of 3,050 feet, and the temperature is 82 degrees constant. As I before remarked, the temperature thus taken is not the exact criterion of the depth of the column of air, because other surroundings in the pit must influence the condition of temperature. Moreover, the density of each 100 feet does not increase in an equal ratio; it is a constantly progressive rate according to the weight of the superincumbent column of air; but invariably, as is the density or weight, so is the heat, in any given volume.

Other mines in the Black Country are now worked to a greater depth than the one to which I have referred as near Manchester.

Passing from mines, we may consider mineral springs, artesian wells, and other volumes of water thrown out on the earth's surface at a high temperature.

Fifty years since I went to Grenelle, in the suburbs of Paris, for the express purpose of inquiring about the artesian well there for supplying water to the great abattoir of Paris. I have not my notes, made at the time, but from memory my impression is that it was

1,700 English feet in depth, throwing up water through a large iron. pipe 50 feet from the earth's surface at a temperature of 140 degrees Fahrenheit. I have noticed, however, that Dr. Hitchcock, in his book "The Religion of Geology," page 169, gives somewhat different figures: "In September 1850 I visited this well, and found the water running still at the rate of 660 gallons per minute at the surface, and half that amount at the top of a tube 112 feet high, at 84 degrees Fahrenheit." I remember that I could not keep my ungloved hand resting on the tube, so I think my estimate of 140 degrees may be nearer the temperature when I visited the well five years previously. At Bath the celebrated mineral waters rise to the surface at 120 degrees, and have done so from the time when the Romans made the site of the fair city one of their principal encampments, attracted by the healing properties of the water springs. Throughout the world, in the coldest and the warmest climates, in all soils, at all heights, hot-water springs are found, some at temperatures near to boilingwater heat. When we remember the intense elasticity or expansiveness of air we cannot put a limit to its descent through crevices of the earth's surface.

If on Mont Blanc its rarity allows water to congeal, why, in some of its unknown depths, should not its density contain sufficient heat to cause the water it presses upon to boil? Water has, in the experiments of air-pressure to which I have referred, been virtually made to boil in cooling the iron condensers, becoming so intensely hot by the heat evolved from the compressed air.

In our experiments and observations we are apt to put limits to nature's powers. We can state what balloonists have experienced of cold higher than the highest mountains-Gay-Lussac ascended 23,000 feet. If such be the result from the extreme rarity of the air decreasing its inherent heat, why should it not, in corresponding depths, force up all but boiling springs? In an enclosed vessel water cannot be heated beyond boiling point, but it must disperse into steam. May not very deep columns of dense air create the steam which causes earthquakes? When railways were proposed and planned 15 miles was to be the extreme of speed. The scientist who sets any limit upon the motive forces in nature is not a philosopher. As we advance in our knowledge of nature's operations we more correctly estimate their inherent power.

I have spoken in uncertainty, and therefore with doubt, of the deeper columns of the atmosphere, but there are columns resting upon the earth's surface the effect of which can be observed and tested. I have splashed through ice and snow in the unroofed, dirty streets