perfect safety. I was also told that frequently large masses of coal are struck off from the sides of the mine, whilst the pitmen are hewing out the coal, as I have witnessed myself; and should a piece of coal strike the lamp upon the side, it would of course break it, and expose the inflammable gas to an instantaneous explo

sion.

The lamps, as they are now constructed, have the following qualities. The piece of glass in front is so strong as to be ensured to carry a ton weight. The rest of the lamp is copper, or strong block tin, supported by three strong iron pillars.

The lamp is now constructed of so small a form, that it may be put into a great coat pocket. A copper lamp may be made for about 30s. or 35s.; and if it be of block tin, the expenses will not exceed half the latter sum.

By means of a very simple apparatus attached to the lamp, I can light the candle with a common match of hyper-oxymuriate of potash and concentrated sulphuric acid in an atmosphere of inflam→ mable air.

And should the lamp be upset (which can only be done wilfully), the candle is instantly extinguished.

I can manage the bellows in such a way that the candle continues to burn with the fire-damp of most mines; and the syphon, which may be understood by the engraving of my lamp in the Transactions of the Royal Society for 1813, is for the purpose of keeping the water upon a level within and without the lamp, while the candle continues to burn, though the inflammable air.be at the firing point.

By a small piece of machinery, which costs about 20s., the bellows may be urged so as to give a constant and sufficient supply of air for the candle for two hours, without winding up; but if the proportion of inflammable air be very great, a slight explosion generally takes place within the lamp, which extinguishes the candle.

When this latter circumstance occurs, the lamp is to be re-lighted, and air given to the candle in the following manner. To the valve of the bellows a leathern nose, or tube, is attached, which, being of such a length as to reach to that part of the mine where there is a current of good atmospheric air, by this means the lamp will of course continue to afford a clear light in the midst of inflammable air.

It sometimes happens that there is a deficiency of oxygen in the atmosphere of a coal-mine. In those cases a very small taper may be used in the lamp, the combustion of which may be supplied by a goat-skin full of atmospheric air, or a few bladders of oxygen gas.

The enormous expense of steel-mills in some mines almost exceed belief. I am informed that in one working of a colliery in this neighbourhood, the expense of steel mills is about 30%. every fortnight; so many of them have to be kept at work at a time to give any thing like a sufficient light.

When I say that the expense of one of my lamps, if made of block tin, does not exceed 17s., it is needless to remark that upon the score of expense there is no comparison.

I made many fruitless efforts to descend a mine charged with inflammable air. At one time the person who invited me to his house, at a considerable distance from Sunderland, went from home when I arrived. Two years afterwards, when I arrived at a person's house (likewise at a considerable distance), who had promised to descend a colliery with me, I found that he had just examined all the parts of the mine, as he said, and that there was no inflammable air to be found in any part of it. This I afterwards found was not the case.

Indeed, the ungenerous opposition I have met with is almost incredible; but the train of miseries detailed in this and my former paper leaves no room for delicacy, and the state of the case demands that some remedy should be applied.

In the mean time all the men of science who came into this neighbourhood examined the lamp, and gave it their entire approval.

Vexed at such treatment, I wished to forget the subject, and let things run their course, when, immediately after an explosion in one of the mines, a sensible and humane letter appeared in the Morning Chronicle newspaper, signed J. H. H. Holmes, which, after much close reasoning upon the subject, put the question whether any of my lamps had been used in those coal-mines which had recently exploded?

After a time, and as no person appeared to take up the subject, I thought it my duty to state, amongst other things, that no person had ever used my lamp in a coal-mine.

From this public correspondence a private one arose; and not long afterwards this Gentleman did me the honour to visit me, and immediately commenced an investigation of the coal-mines, in order to give some general information upon this very interesting subject.

It will be unnecessary, after the preceding statements, to trouble the Royal Society with any further particulars, except the two following certificates, which were drawn up, and signed, according to their respective dates, on the spot where the trials were made, which, it is expected, place the value and security of the lamp beyond a doubt. The trial within the mine was conducted at the place where 24 persons were not long since killed by an explosion.

FIRST CERTIFICATE.

(Copy.)

Herrington Mill Pit, Oct. 16, 1815.

An experiment took place this day on Dr. Clanny's lamp for preventing explosions in coal-mines. It was effected at the mouth of

the upcast shaft of the Herrington Mill Pit, by means of inflammable air obtained from a cast-iron tube communicating with the Hutton seam, and witnessed by the undersigned.

In order to ascertain the quality of the gas given out at this tube, a bladder was filled from it, and on trial its contents proved to be carbureted hydrogen gas of the purest nature.

One end of a leaden pipe was affixed to the iron tube; the other end placed within a room which was quite closed up, except at the door where the pipe entered. In a very short time the carbureted hydrogen gas became mixed with the atmospheric air of the room up to the firing point, when the lamp, with a lighted candle within it, was carried into the centre of the room; and after conveying two or three draughts of air through the bellows, an explosion took place, which extinguished the candle without communicating to the surrounding inflammable atmosphere. This experiment was practised a second time, and the same results followed.

On witnessing the experiment, the under-mentioned Wm. Patterson and Joseph Gleghorn declared that they would go into any part of a mine without any fear, if lighted by this lamp.

(Signed)

J. H. H. HOLMES.
WM. PATTERSON.
Jos. GLEGHORN.
ANTH. HOPPER.

GEORGE PATTERSON.

SECOND CERTIFICATE.

(Copy.)

Monday, Nov. 20, 1815.

Dr. Clanny and Mr. Holmes (one of the undersigned) left Sunderland this day, for the purpose of experimenting upon Dr. C.'s lamp, in some of the most inflammable parts of a coal-mine; for notwithstanding that it was satisfactorily experimented upon on Oct. 16, within a room filled with inflammable air at the firing point, it was thought expedient to carry it into those parts of a mine where its benefit must ultimately be produced.

They descended the Herrington Mill Pitt, which is 101 fathoms in depth from the surface; and having proceeded upon the examination of the mine, found the most inflammable part at the bottom of a staple, which was closed about 20 feet down by scaffolding, and made to communicate with the Hutton seam, which, being now worked out, is full of inflammable air. [And from this the tube runs by which we were enabled to make the experiments of Oct. 16, 1815.-W. R. C.]

Much caution was required in keeping the candles from approaching too near the staple, as their appearance, when held near the mouth, clearly indicated that, had they been introduced too far, an explosion must necessarily have followed.

Dr. Clanny and John Birkbeck, a man employed in the mine, stood at the top. Mr. Wm. Patterson, a very able and intelligent man, descended half down the staple, and Mr. Holmes stood upon the scaffolding. The lamp with the lighted candle was handed by Dr. Clanny to Mr. Patterson, who descended with it to Mr. Holmes; and after the bellows of the lamp were urged a few seconds, a slight flash occurred within the body of the lamp, and the candle was immediately afterwards extinguished. No particular caution was observed with the lamp, as a confidence in its security resulted from the experiments of Oct. 16; and if a further proof of this was necessary, it was afforded by the presence of Mr. Patterson and Birkbeck, both of whom declared "that if the candle had communicated with the circumambient air on the spot where the experiment took place, the mine would have been blown to pieces."

(Signed)

J. H. H. HOLMES.

WM. PATTERSON.

JNO. BIRKBECK.

ARTICLE IX.

ANALYSES OF Books.

Nova Genera et Species Plantarum quas in Peregrinatione ad Plagam Equinoctialem Orbis Novi collegerunt, descripserunt partim adumbraverunt Amat. Bonpland et Alex. de Humboldt. Ex Schedis autographis Amati Bonplandi in Ordinem digessit Carol. Sigismund. Kunth. Accedunt Tabulæ Æri incise, et Alexandri de Humboldt Notationes ad Geographiam Plantarum spectantes. Tomus Primus. Paris, 1815. super-royal 4to.

(With a Plate.)

HUMBOLDT, in a long introduction to this volume, gives an account of the different publications in which he has consigned the immense number of facts which he collected during his residence in South America, and informs the reader that the object of the present work is to put botanists, at a small expense, in possession of the descriptions of the American plants which he and his fellow traveller collected. We doubt, however, whether a book printed like this, on the largest sized quarto paper, and with a wide margin, can be afforded at a small expense. Nor can there be any doubt that Humboldt would have been much more useful to science if he had published all his works in a less expensive form, and had been somewhat more concise in his style. Fortunately the desire for magnificent books is losing ground in this country, and we wish to

see a simplification in the taste of bibliography all over the world. The magnificence and expense of Humboldt's books must have rendered their sale exceedingly limited ; a circumstance which could not but tend very materially to circumscribe his reputation, and to prevent the general diffusion of the facts which he published; for the purchasers of very expensive books are very seldom those who are best qualified to appreciate their merit, or to draw advantage from them. We are persuaded that Baron von Humboldt would very materially increase his reputation, and at the same time confer an important obligation on science, if he would republish all his works on South America in a small octavo form, and freed as much as possible from all repetitions and unnecessary details.

Humboldt and Bonpland, in their five years' travels in South America, from north latitude 12° to south latitude 23°, collected 5,800 species of plants. Of these 5,500 were phanerogamous plants, 3,000 of which were new, and unknown before to botanists. That this number is very considerable, will be evident from this, that in the Systema Vegetabilium of Willdenow, published from 1797 to 1811, the whole phanerogamous plants of South America do not exceed 3,188 species; while the plants of New Holland at present known do not exceed 3,800 species.

The species of phanerogamous plants known to grow in South America within the Tropics, including those that have been lately added to the list by Humboldt and Bonpland, Ruiz and Pavo, Persoon, Mutis, &c. amount to 13,000.

Botanists at present are acquainted altogether with 44,000 species of plants; while the whole number mentioned by the Greeks, Romans, and Arabians, does not exceed 1,400. The proportion of plants which grow in latitudes 0°, 45°, and 68°, are as the numbers 12, 4, 1. The mean annual temperature in these regions is $140, 551, 321; the mean summer temperature is 8210, 70°, 5310

Within the tropics the monocotyledinous plants are to the dycotyledinous as one to six; between latitudes 36° and 52°, as one to four; and at the polar circle, as one to two. In Germany, the monocotyledinous plants are to the whole phanerogamous plants as 1 to 44; in France, as 1 to 4%. The same proportion holds in North America; and likewise, according to Mr. Brown, in the temperate zone of New Holland; while in Iceland and Lapland the monocotyledinous plants are to the whole phanerogamous as one to three.

The annual monocotyledinous and dicotyledinous plants in the temperate zone constitute th part of the whole phanerogamous plants. In the torrid zone they scarcely amount toth part; and in Lapland to th.

The following table exhibits the number of species of the natural families of phanerogamous plants which grow spontaneously in France, Germany, and Lapland, with the ratio of each to the whole number of phanerogamous plants growing in the country.