1

Extract of a letter from Thomas Ley, Esq., of Philadelphia, to Dr. William Elford Leach, on the subject of the Genus Ocythoe.

Arithmetical investigations upon the extraction of roots, by Lewis Francis Bastard, Esq., of Geneva.

FEB. 11. On the variation of the compass, by John Ross, Captain, R. N.

FEB. 18. On the irregularities of the compass needles of H. M. SS. Isabella and Alexander, caused by the attraction of iron contained in them, by Captain Edward Sabine, Royal Artillery.

FEB. 25. Some observations on the formation of mists in particular situations, by Sir Humphry Davy, Bart.

Observations on the dip and variation of the magnetic needle and intensity of the magnetic force, made during the late voyage in search of a north-west passage, by Captain Edward Sabine, Royal Artillery.

On the action of crystallized surfaces upon light, by Dr. David Brewster.

MARCH 4. An account of the fossil skeleton of an animal, several parts of which have been described to the Society in three separate papers, by Sir Everard Home, Bart.

MARCH 11. On the pressures which sustain a heavy body in equilibrium, when the points of support are more than three, by Charles Bonnycastle, Esq.

168

ART. XXI.

Miscellaneous Intelligence.

I. MECHANICAL SCIENCE.

§1. ASTRONOMY, OPTICS, AGRICULTURE, THE ARTS, &c.

1. Theory of the Rainbow. A new theory of the common rainbow has been advanced by Dr. Watt, of Glasgow, by which he accounts for the effect without refraction in small drops of water. The rainbow, it is stated, is frequently seen towards the quarter where no rain is falling, and where, of course, it cannot be caused by drops; but it is observed, as a constant attending circumstance, that the edge of a cloud is always at those times between the observer and the sun; and Dr. Watt attributes the rainbow to the beams of the sun refracted by this edge, and thrown on to the dark sky opposite, which receives them as a screen. The cause and effect are said to be so closely connected, that, with a little practice, the appearance of the bow may often be predicted from the state of the clouds, with great certainty. There are, however, many phenomena which cannot be explained in this way, and which so exactly resemble the rainbow, we can scarcely separate them. The bow formed in the mist of a cataract, as at Terni, or that produced by throwing water from a syringe against a wall, or any obstacle opposite, must be accounted for by refraction in drops; and where the shower is seen falling, and the tints of the rainbow seem to clothe the buildings or other objects beyond them, the phenomenon appears to have the same origin.

2. New Comet.- A comet has lately been discovered at the observatory of Konigsberg, in the constellation of the Swan. It is not visible to the unassisted eye.

3. On Budding, and on the Fig Tree, in a Letter to the Editor.

SIR,-Whether the following brief observations and notice of improvement in two operations of the art of horticulture may be of sufficient importance to obtain the honour of occupying a page in some future number of the Journal of Science and the Arts must be left to better judgment than that of their author to determine.

When I first began to practise budding or inoculating in the above art, conformably to the directions of gardening books in general, and those of Miller and Mawe and Abercrombie in particular, I made the transverse cut in the bark of the stock above, and the longitudinal slit beneath, and consequently thrust the bud downwards to its place of rest, and was very often mortified by

a want of success. The Rev. I. Lawrence's treatise on the same subject, entitled The Clergyman's Recreation, recommends a method the reverse of this, that is, to make the transverse cut beneath, and the perpendicular one above, and thus to lead the bud upwards to its position; by following this direction I have seldom failed in the operation. It was formerly supposed that the sap ascended in the vessels of the bark and between that and the wood; now it is ascertained that it descends in those vessels; the reason of the better success of my latter mode of practice is obvious; the bud in the superior position receiving an immediate and plentiful supply of sap, which is denied to it by the cross cut obstructing and diverting the invigorating fluid, in the inferior situation.

It is well known, that fig-trees (ficus carica) produce a second crop of green figs in the autumn in much greater abundance than the spring crop. As these autumnal figs are never known to ripen in this country, they should be rubbed off as soon as they make their appearance, which is often early in August, and through that month and September. I have not seen one gardening directory where this is recommended to be done till the month of November; by which time they are grown many of them to nearly their full size. By suffering them to remain till this period, the trees will have been supporting and maintaining the greater part of this useless burthen of fruit for at least three months, and must be supposed to be in consequence much weakened by it, and rendered indisposed to produce fruit in the following spring. Besides, the breaking off these immature figs when their stems are become large, unavoidably occasions considerable wounds in those young shoots to which they are attached; which, as the sap is then at rest, are not so readily disposed to heal, and from this circumstance are commonly killed (at their extremities at least), by the frosts immediately succeeding and attacking them in their unhealed state. Rubbing off these autumnal fruit as soon as they appear, leaves neither wound nor scar of any consequence; and two figs may very often be observed in the spring to issue at the very joint where one was rubbed off. When I first attempted this innovation, I had some suspicion that it would tend to force out more young fruit at that improper season, which might otherwise remain latent till the spring, but I never found my suspicion to be realized. With the above management strictly adhered to, I have very seldom known my fig-trees fail of displaying an abundant shew of fruit at the proper season.

Travellers tell us, that in those countries where the fig-tree is indigenous these autumnal fruits ripen as well as the spring crop. But if they do so, the supporting and ripening two crops in one year must, surely, prevent those trees subject to so great exertion, generally, from bearing fruit the following year. We know that one full crop of fruit commonly disables many of our fruit-trees, apples, for instance, or apricots, (if the fruit of these latter are not duly and seasonably thinned), from producing fruit the next season. And much more may we expect this effect to follow when two crops, (indeed, Dr. Shaw says, that sometimes three are ripened), are born and matured in one year. Should, however, what I have just supposed be the fact, it would completely remove the difficulty apprehended in the account of the fruitless fig-tree in St. Mark's Gospel*, and Dr. Hammond's interpretation of that disputed passage would be the true one, Οὐ γὰρ ἦν καιρὸς σύκων. For, (not as our translation has it " the time of figs was not yet," but literally), it was not a season of figs;-it was not the fig-year; -the fruit-bearing year for that particular tree.

I am most respectfully your's,

Dyrham Rectory, near Bath.

G. SWAYNE.

4. Prevention of injury to Plants from Insects. We recommend to gardeners and others, at this season of the year, the use of the ammoniacal and tarred liquor, obtained from the distillation of coals in the making of gas, for the purpose of keeping grubs and other insects from trees and plants, and of destroying them. The fluid is not at all hurtful but rather beneficial to the plants, and if merely put round wall-trees on the wall and ground, will keep the snails and other insects from them.

5. New Light-houses. A light-house has been erected at the point of Ayre, at the Northern extremity of the Isle of Man; and two others have also been erected on Calf Island, at the Southern extremity of the Isle of Man. They were lighted on the evening of Monday, February 1, and will henceforward be lighted from evening till morning.

6. Substitute for Lithographic Stones. A mixture of plaster of Paris and alumine, left to harden in a smooth metallic mould, is said to answer perfectly well in the place of limestone in the lithographic art.

7. Grass Rope. Experiments have been made at Portsmouth on the application of a grass, a common product of New Zealand, to the manufacture of large and small ropes, of which a favourable report has been given. The grass is strong, pliable, and very silky in its nature, and may be cut thrice a year. It may be brought into this country at the estimated price of eight pounds per ton, or about one-seventh the price of hemp.

8. Premium for Flax. A premium of fifty pounds has been offered by the Prince Regent, as duke of Cornwall, and lord of the forest of Dartmoor, to the person who this year shall cultivate the greatest number of acres in flax.

9. Linen and Thread from Nettles. Some experiments on the preparation of linen and thread from the flos of nettles have been made lately in Ireland. The thread in colour, strength, and fineness, was equal, if not superior, to that obtained from flax, and the linen had the appearance of com on grey linen.

II. CHEMICAL SCIENCE.

§ 2. CHEMISTRY.

1. On Nitric Acid; in a Letter to Andrew Ure, M.D., M.G.S. by Richard Phillips, F. R.S. E., F. L. S., &c.

SIR,

I request your attention to some additional observations respecting nitric acid. If language has any meaning, you still claim as your own discovery, the exact composition of this acid. I am prepared not only to vindicate the correctness of my former statements, but again to incur accusations of ignorance, and bitter reproaches, for questioning the justice of your pretensions. Your first paper*, upon which I have already offered some remarkst, I shall refer to as the memoir, and the second ‡ which is the more immediate subject of my present communication, I shall denominate the reply.

In my remarks on the memoir, I observe that you had denied the correctness of every previous analysis of nitric acid; in the reply you say, "this is a mis-statement of my language. In a short introductory paragraph of eleven and a half lines, I detail from Doctor Henry the discordant numbers of two eminent modern chemists. But I no where assert that every previous analysis was incorrect." Now, Sir, permit me to refer to this paragraph, and to examine what occurs in addition to your present description of its contents: of nitric acid you say, "the exact proportion of its two constituents, azote and oxygen, is a problem which seems hitherto to have baffled the best directed efforts of modern science. M. Gay Lussac states, as its composition in 100 parts, -30.4 azote + 69.6 oxygen; and Mr. Dalton 26.7 azote + 73.3 oxygen. Thus discordant," you exclaim, are the latest determinations. I hope soon to be able to present to the public some researches, which may possibly tend to clear up this mystery."

Allow me to inquire, how the best-directed efforts of modern