of light, reminding an observer of the zodiacal light in its form, but rapidly rising and becoming brighter. When at an altitude of about 40° due east, the meteor emerged like a fireball from a roman candle, of a blue colour, about a quarter of the apparent diameter of the full Moon in width, and drawing after it a trail of reddishcoloured sparks, 21° or 3° in length; as it passed overhead the outpouring and falling behind of the matter forming the train became distinctly visible. At Wimbledon, near London, where the meteor was seen by Mr. F. C. Penrose, it vanished suddenly, or at any rate very rapidly, about 8° N.W. of a Lyra. It traversed the entire length of the valley of the Thames-a distance of seventy-five miles from forty-one miles above the Nore to twenty-seven miles above the earth's surface in the neighbourhood of Henley-on-Thames. On the average of four separate accounts, estimated by different observers between four and ten seconds, the time taken by the meteor to travel the entire distance, about seventy-five miles, was six seconds and a half. On this estimate the velocity of the meteor relatively to the earth's surface was about eleven miles per second. The direction of the actual position of the meteor's flight was from a point in the neighbourhood of the constellation Taurus, between Taurus and the head of Cetus.

The distance of the meteor at the moment of its disappearance from Wimbledon, collectively determined from these accounts, is about thirty-six miles. At Wimbledon, Mr. F. C. Penrose heard a loud report, like that of a cannon fired off at the distance of some miles, distinct enough to be heard very plainly by one other person at Wimbledon, about two minutes and twenty seconds after the meteor disappeared. Sound, with its ordinary velocity of 1,090 feet per second in common air, would take two minutes and fifty-four seconds to travel the entire distance of thirty-six miles from the point of the disappearance of the meteor to Wimbledon. Considering, as before, the difficulty of fixing the exact position of the apparent path of the meteor, and hence the approximate nature of the real path concluded from the independent statements of the observers, the agreement of the calculated time with the time observed by Mr. Penrose, between the disappearance of the meteor and the occurrence of the sound, must be regarded as a near coincidence. There can be little doubt from this circumstance-from the nature of the sound, the great apparent brightness of the fireball, and from its near approach to the earth-that this meteor was really a detonating fire-ball.

Detonating meteors are described in the British Association Reports as having taken place in England during the last five years, very nearly on the same date of the year as the meteor of the 21st of November, 1865.

The epochs of the 9th-11th of February, and the 19th-21st

of November are, therefore, dates deserving special attention, partly with a view of determining for the future the directions of the detonating meteors, and partly as showing, by their frequent return within very narrow limits of time about these dates, that aërolitic meteors, like the acknowledged star-showers of August and November, revolved in fixed orbits round the Sun.

In a note on the spectrum of the variable star a Orionis, W. Huggins, F.R.S., and W. A. Miller, M.D., LL.D., F.R.S., mentioned an important change which has been recently observed in the spectrum of this star. Orionis is a variable star of great irregularity, both of period and of extent of change of brightness. These observers have recently found that the group of lines, and "shading as if of fine lines," terminated at its more refrangible end by the strong line No. 1069 5 in their diagram, is not at present visible in the spectrum of the star. The absence of this group is of great interest in connection with the variability of the star's light, especially as the time of disappearance of this group coincides with the epoch of the maximum brilliancy of the star.

Mr. Baxendell, whose successful prosecution of this branch of astronomy is so well known, mentioning this star, says: "The variable a Orionis is irregular both in the extent of its variation and the duration of its period. I have often thought its light was at times variable in colour as well as intensity, being sometimes perceptibly more ruddy than at others."

The variation in colour, so well described by Mr. Baxendell, corresponds exactly to the change in colour of the star which would be produced by the absence or presence of the group of lines referred to above, since the position of this group in the spectrum is about the boundary of the "orange" towards the "yellow."

The Astronomer Royal read an important and interesting paper "On the supposed possible Effect of Friction in the Tides in influencing the Apparent Acceleration of the Moon's Mean Motion in Longitude," in reference to a communication to the Institute of France by M. Delaunay, in which he explains a portion of the apparent acceleration of the Moon as possibly due to a real retardation of the rotation of the earth, and conceives that such retardation may possibly arise from friction in the tidal movement of the waters. In suggesting this explanation, he lays down as fundamental theorems the two following:-First, that if the solid globe of the earth were covered with water, there would be high water under the Moon (considered as the only tide-producing body); secondly, that the effect of friction would be to make the semi-diurnal tides later than they would be if there were no friction.

Any treatment of the tides is, necessarily, very imperfectly applicable to the real motion of the waters, under all their com

plicated circumstances of unsymmetrical boundaries, varying depths, and unknown laws of friction. Still attempts have been made upon different hypotheses admitting of mathematical treatment, by which the different points of M. Delaunay's theory may be tested.

Newton, Laplace, and Airy agree in this, that there will be low water under the Moon. In a subsequent part of the 'Principia,' Newton thinks that the high water would in some measure follow the Moon's place.

Airy shows that the effect of friction is to accelerate the time of each individual tide.

It is a result of this friction that the velocity of the earth's rotation is not affected.

It is a further result of this friction, and the consequent disturbance of the form of the waters, that the Moon's motion is affected; her orbit is made to become large, and her motion in longitude is retarded. The phase of low water (and consequently of the tide) is accelerated by the friction. Amongst the conclusions arrived at in this elaborate memoir are the following:-The friction of the tides does not tend at any instant either to accelerate or to retard the rotation of the solid globe. The friction of the tides produces a retardation of the Moon's mean longitude.

It would seem probable that the reaction of these forces will in some way produce a retarding effect on the earth's rotation. There are other instances in the lunar theory in which the Moon's action on the equatorial protuberance of the earth is accompanied by action of that protuberance on the Moon, both producing wellrecognized effects. But in a case like this before us, where the very existence of the force depends on friction, and consequent disturb ance of the law of vis viva, the author does not profess himself able to follow out all the consequences. It will probably be difficult to say what is the effect of friction in more complicated cases. Conceive, for instance (as a specimen of a large class), a tide-mill for grinding corn. The water which has been allowed to rise with the rising tide is not allowed to fall with the falling tide, but, after a time, is allowed to fall, thereby doing work and producing heat in the meal formed by grinding the corn. It is not doubted that this heat is the representative of vis viva, lost somewhere, but whether it is lost in the rotation of the earth, or in the revolution of the Moon, Prof. Airy is quite unable to say.

In an addendum, dated April 5, the Astronomer Royal says he has at length discovered two terms which appear to exercise a real effect on the rotation of the earth. By a process of mathematical reasoning, he proves that there is a constant acceleration of the waters as following the Moon's apparent diurnal course. As this is opposite to the direction of the earth's rotation, it follows that from the action of the Moon there is a constant retarding force on the rotation of the water, and therefore (by virtue of the friction between

them) a constant retarding force on the rotation of the earth's nucleus.

The author concludes by saying:-"I am very happy to give my entire assent to the general views of M. Delaunay on the existence of one real cause for the retardation of the earth's rotation."

C. G. Talmage, Esq., gives an account of a probable observation of Biela's comet. He states that while sweeping for Biela's comet, on the 4th of November last, he came upon a nebulous object which is thought very likely to have been the comet. From brief opportunities afforded to Mr. Barber and Mr. Hind, it is very probable that Mr. Talmage's object was really nucleus L of this comet. Unfortunately the weather was too unfavourable to allow of subsequent observations.

Mr. Huggins, F.R.S., has contributed an interesting paper on "The Bright Granules of the Solar Surface," to which we shall refer in our next number.

III. BOTANY AND VEGETABLE PHYSIOLOGY.

RUSSIA. The Bulletin of the Imperial Society of Naturalists at Moscow,' vol. xxxviii., No. 3, 1865, contains fourteen short botanical papers, morphological, anatomical, and physiological, by Paul Reinsch, with two plates of microscopic drawings delineated from nature, which are very valuable contributions to science. As the plants which have furnished the illustrations are familiar and easily obtained, the observations of M. Reinsch may be readily verified. Four of these papers are devoted to the subject of vegetable cyclosis, or the motion of the protoplasmic currents in the individual cell. The plants and the parts in which M. Reinsch has observed cyclosis, and which have furnished the beautiful illustrations of the first plate, are-1. The cilia on the leaves of Sempervivum tectorum; 2. The youngest developing cells in the whorls of Nitella syncarpa; 3. The individual cells of the root and parenchyma of Hydrocharis morsus rana; 4. The cells of Closterium lunula. M. Reinsch describes three kinds of cyclosis, viz. the rotatory movement which is confined to one portion of the cell; the circulatory movement, where the proto-plasmic current sweeps around the entire circumference of the cell; and the rotatocirculatory, which is a combination of the two preceding movements. The rate of motion in the cells, or parts of cells, is variable, being accelerated and retarded by a rise or a fall of temperature. The quantity of protoplasm in the current is also variable. remainder of these papers consist of interesting articles "On the reproduction of Bryum by axillary buds;" "On the Infusoria in the cells of Sphagnum;" "The development of the Stellate cell in the

The

pith of the Cyperaceae;" "Acrosyncarpia in Bryum cæspiticum," being an abnormal development of the sporangium; "The antheridia of Nitella syncarpa ;" "The reproduction of Tetraspora lubrica," of a new species of Staurastrum, and also of those familiar Desmids, Euastrum margaritiferum, Ehren., and Cosmarium cylindricum, Ralfs.; and, lastly, a paper on the development of the spores of Scapania nemorosa, Nees.

FRANCE.-The Influence of Light on Plants.-The Parisian Academy of Sciences have received a highly interesting communication from M. Duchartre on certain well-known plants, which, too weak to support themselves, tend to twine around the nearest objects. They generally do this from left to right, that is, inversely to the motion of the sun, but some species turn in the contrary direction, and it is impossible to make either the one or the other change its direction. Palm, Von Mohl, Dutrochet, and latterly Darwin, have successively expressed the opinion that light was the cause of this tendency; but further experiments being wanting to confirm this theory, M. Duchartre, who had discovered that the Chinese yam could live a long while in the dark, resolved to try the effect of absence of light upon it. At the end of May last he placed one in a pot, and as soon as it showed its stem above ground he took it down to a cellar, where it remained in complete darkness until the 2nd of August following. The stem, in the course of seven weeks, grew to the length of a metre and a half. It looked withered and whitish, but was upon the whole strong and even stiff and perfectly straight, showing nowhere a tendency to twine itself round the stick which had been placed there for its support. Another yam was planted nearly a month later, and left exposed to daylight until it had twined itself twice round its stick. It was then taken and placed in the cellar, where its stem, still obeying its natural tendency, went round once more, but in a more vertical direction than before; after which it grew straight up along its pole, to which it was fastened as it grew. It was now again taken up into the garden, where it immediately began to twine round again, making five close turns; and when it was once more taken down into the cellar it continued its growth again in a straight line, and so on, according as it was alternately in the light or in the dark. The same phenomenon was observed, not only in the yam or Dioscorea Batatas, but also in the Mandevillea suaveolens; but, on the other hand, the bean and the Ipomea purpurea continue to twine round their supports in the dark.*

In the Bibliothèque Universelle' of the 25th of March, 1866, there is a "Note on some new facts in Botanical Geography" by Edmond Boissier, from which we learn that there are certain

* Galignani's Messenger.'