Philosophical Magazine

things, not "through a glass darkly," but more nearly as they are; and that the boundaries of physical and metaphysical science, now so far asunder, may be made to approach each other.

In the present state of our knowledge, our business should be, to collect, arrange, and compare phænomena, rather than to speculate upon their nature. Nevertheless, I cannot refrain from observing, that the circumstances attending the luminous appearance of living animals, are much more favourable to the supposition of light being a property than a substance. The quantity of light emitted by an animal in a certain time, (admitting it to be matter) far exceeds that which could be possibly supplied by the sources from whence it is usually supposed to be derived. Thus the luminous appearance of some medusæ may be continued with the intermission of short intervals for an indefinite time, notwithstanding the creature be kept in darkness, and without any other food than what a small quantity of filtered sea-water would afford. The uninterrupted and long continued light that is sometimes evolved by the luminous sacs, and the ova of the glow-worm, is also inconsistent with the notion of an accumulation and subsequent dispersion of a material substance.

I shall terminate this paper by an enumeration of the several conclusions, that are the result of the observations I have been able to make upon the phænomena of animal light.

The property of emitting light is confined to animals of the simplest organization, the greater number of which are inhabitants of the sea.-The luminous property is not constant, but in general exists only at certain periods, and in particular states of the animal's body.-The power of showing light resides in a peculiar substance or fluid, which is sometimes situated in a particular organ, and at others diffused throughout the animal's body.-The light is differently' regulated, when the luminous matter exists in the living body, and when it is abstracted from it. In the first case, it is intermitting, or alternated with periods of darkness; is commonly produced or increased by a muscular effort; and is sometimes absolutely dependent upon the will of the animal. In the second case, the luminous appearance is usually permanent until it becomes extinct, after which it may be restored directly by friction, concussion, and the application of warmth; which last causes operate on the luminous matter (while in the living body,) only indirectly, by exciting the animal.-The luminous matter, in all situ

ations,

ations, so far from possessing phosphoric properties, is incombustible, and loses the quality of emitting light, by being dried, or much heated.-The exhibition of light, however long it may be continued, causes no diminution of the bulk of the luminous matter. It does not require the presence of pure air, and is not extinguished by other gases.

The luminous appearance of living animals is not exhausted by long continuance, or frequent repetitions, nor accumulated by exposure to natural light; it is therefore not dependent upon any foreign source, but inheres as a property, in a peculiarly organized animal substance or fluid, and is regulated by the same laws which govern all the other functions of living beings.

The light of the sea is always produced by living animals, and most frequently by the presence of the medusa scintillans. When great numbers of this species approach the surface, they sometimes coalesce together, and cause that snowy or milky appearance of the sea, which is so alarming. to navigators. These animals, when congregated on the surface of the water, can produce a flash of light, somewhat like an electric coruscation. When the luminous medusæ are very numerous, as frequently happens in confined bays, they form a considerable portion of the mass of the sea, at which times they render the water heavier, and more nauseous to the taste; it is therefore adviseable to always strain sea-water before it is drunk.

The luminous property does not appear to have any connection with the economy of the animals that possess it, excepting in the flying insects, which by that means discover each other at night, for the purpose of sexual congress.

Explanation of the Figures (Plates I and II.)

Fig. 1. The cancer fulgens, discovered by the Right Hon. Sir Joseph Banks, of the natural size,

Fig. 2. The same animal magnified.

Fig. 3. The medusa pellucens, also found by Sir Joseph Banks, represented of the natural magnitude.

Fig. 4. The limulus noctilucus, discovered by Captain Horsburgh, considerably enlarged.

Fig. 5. The luminous medusa, discovered by me, which I conceive to be the medusa hemispherica: it is shown of the largest size I met with.

Fig. 6. The central process of this animal's body magnified, in order to explain its structure. The thick tentacula

in which it terminates are seen covered with small cups or suckers.

Fig. 7. The beroe fulgens, discovered by me, shown in its most elongated or relaxed form, which it assumes commonly when swimming quickly.

Fig. 8. The same animal in the most contracted form.

Fig. 9. The minute species of medusa, discovered by me, which is the most frequent cause of the luminous appearance of the sea, represented of the natural size.

Fig. 10. The same animal magnified, exhibiting a puckered or tucked-in appearance on one side.

Fig. 11. Is the animalcule discovered by Forster, of the natural size.

Fig. 12. The same, greatly magnified, to show the intestinal parts. Both these figures are copied from the original drawings, in the possession of the Right Hon. Sir Joseph Banks.

Fig. 13. Is an enlarged view of the inferior surface of the abdomen of the lampyris lucida, after the integument had been removed. a a a represent the three masses of luminous substance which are applied to the three last rings of the abdomen. bbb the arrangement of cellular or interstitial substance on the other abdominal rings, which gives the pale colour to the whole belly of this insect.

Fig. 14. Represents the common glow-worm, with the posterior portion of the back cut away to expose the sacs of luminous matter in situ on the last ring of the belly. a indicates the sac of one side; the intestine is seen to lie between them.

Fig. 15 and 16. Are the sacs of the glow-worm prodigiously magnified to show their structure. Fig. 16 is cut open to expose the luminous matter it contains: the coat of the sac is still seen to preserve its figure.

Fig. 17. Is the elater noctilucus, with the shell of the corcelet removed on one side, by which the organ of light is uncovered. a the yellow transparent spot of the corcelet. b the oval mass of luminous substance surrounded by an irradiation of the interstitial substance. c the ends of the mus cles which were on the inside of the corcelet.

Fig. 18. Is the posterior angle of the corcelet of the elater noctilucus magnified. a the radiated appearance which the interstitial substance has round the oval mass of luminous matter. This mass is seen to consist of a number of smaller parts. shows the appearance of the interstitial substance, where it passes down between the muscles. c the ends of the muscles of the back. d the shell of the corcelet.

Fig. 19. Represents the elater ignitus. a is the mass of luminous substance of one side, seen indistinctly through the back part of the semitransparent portion of the corcelet. is the luminous mass of the other side, exposed by removing a part of the shell of the corcelet.

XIX. A List of about 280 Mines of Lead,-some with Zinc, Manganese, Copper, Iron, Fluor, Barytes, &c. in and near to Derbyshire. By Mr. JOHN FAREY, Sen., Mineralogical Surveyor.

SIR, I INCLOSE a list of such mineral Veins or Mines as

have been visited or information obtained concerning, in the course of the mineral Survey in which I have been engaged, since the year 1807: I do not offer it as a complete list of the mines, but as a selection from the most productive and important ones, or those which are calculated to illustrate some point of interest, in the progress of mining, or in a geological view. As I observed respecting the List of Collieries (in your 35th volume, page 432), many of these Mines were long ago discontinued, but as in most instances, further quantities of ore lay in the deep, below level or beneath the toadstone strata, the recording of such, may not be without its uses. In the manuscript of the first volume of my Report, which is now printing by order of the Board of Agriculture, I have given an alphabetical list of these mines, with the most important or remarkable products, and particulars respecting each; which mines all produce blue lead ore or galena, I believe, and the greater part of them in rake-veins in the limeston rocks; and I there distinguish, the other variable and more rare particulars, such as pipe- veins, flat-works, and in which of the limestone rocks or toadstones, &c. they occur; galena being found in toadstone between the limestones, or in the shale above them; white or green ores of lead, or silver combined therewith in notable quantities: copper ore, calamine, black-jack, black-wad, pyrites (iron), ochres; fluor spars, blue-john, barytes, calcareous crystals; sulphur, bitumen, petroleum; china-clay, steatite; cherts, toadstones, or clay-wayboards in the strata or veins: crooked, crossing, haded or squinted rakes; caverns, slickensides, faults, gravel or extraneous fossils in the veins, &c.

Without doubt, some mines that present instances, and perhaps, striking ones, of the particular phænomena mentioned above, or perhaps other curious ones, have escaped

me in prosecuting my Survey, or in compiling these lists; in which case, I shall be thankful to any of your readers who may happen to possess or discover any such, if they will freely communicate them, as well as their remarks on the above, in order that as complete and useful lists and particulars as possible, may at length be given to the public, in my intended Mineral History and Map of this highly interesting district: which last will show, the great mining tract of limestone strata in Derbyshire and Staffordshire, to be extended over 105,000 acres, without including the shale and other occasional depositories of metallic ores in the district.

I am, sir,

12, Upper Crown-street, Westminster,

Feb. 1, 1811.

Places' Names.

Your obedient servant,
JOHN FAREY, Sen.

Names of Mines.

Rake.

Alport, in Yolgrave Abbotshole,-Blithe,—and Wheels