Oct. 20.-The needle at noon vibrated at times six minutes : the next day the wind blew from the S. E. with rain. Nov. 11.The variation extraordinary this morning, in the evening there was a violent storm from the S. W. which lasted 36 hours, and the gusts were remarkable for their strength and frequency. Nov. 15.-At noon the needle was steady, until it began to rain; it then vibrated five minutes and ten seconds. Nov. 17.-At the commencement of the snow storm the needle vibrated eight minutes and thirty seconds. Rain fallen{ Between noon of the 1st Oct. Between noon of the 1st Nov. 3.661 inches, ARTICLE IX. Account of a luminous Meteor seen at Sunderland. By Mr. SIR, Renney. (To Dr. Thomson.) Bishopwearmouth, Nov. 12, 1813. PERMIT me, through the medium of your Journal, to lay before your readers the following particulars of what I consider a very uncommon phenomenon; in the hope that you, or some other scientific Gentleman, will have the goodness to afford an explanation through the same channel. On Wednesday evening, the 10th of this month, about 40 minutes after six, the moon having just risen, but was not visible, owing to a very dense cloud (whose altitude was 7°), the most opaque I ever recollect to have seen. From behind this cloud there appeared a stream of light, which extended across the hemisphere, and so dense that y in Pegasus, and a in Aquila, were obscured by it; the edges of which at intervals diverged into lines, diminishing its breadth: but, that I may afford a more perfect idea, I shall give its extent by the stars that appeared in or near the northern and southern edges :— It was obscured by a dark cloud in Taurus Poniatowski, and extended visible through Serpentarius to the horizon. I immediately waited upon Thomas Jones, Esq. a Gentleman of considerable scientific acquirements, who possesses a very excellent astronomical and philosophical apparatus (to whom I am under many obligations for their use); and although he was at home, and disengaged, I found that before he could come to the door this immense volume of light had lost much of its lustre, and was so reduced in substance that y in Pegasus now became visible near the centre. Mr. Jones observed, that he "had seen many uncommon phenomena of nature, but none like the present.' Its duration, I believe, did not exceed six minutes; for, at the time I first saw it, I think it was then in its greatest splendour, but in about three minutes it entirely disappeared. In the north the Aurora Borealis was faintly playing, from which to the south the heavens (except the cloud before alluded to, and a cloudy horizon) were clear, and had the appearance of frosty weather. The wind at the time was easterly and much rain had fallen during the day. I am of opinion that this phenomenon could not be caused by the above-mentioned cloud concentrating the rays of the rising moon; for if it had, it could not have caused it either to extend across the whole hemisphere, nor to have had that density which this possessed: and at the same time I may remark, that the moon was not the centre; but, on referring to a celestial globe, will be found to have been to the north of it; consequently, if the moon had caused this luminous appearance, it would have been in a different direction; besides, the stream of light was not in a right line, but rather bearded to the north. I am, with much respect, Sir, Your most obedient humble servant, ROBERT RENNEY. ARTICLE X. ANALYSES OF Books. A short Account of Experiments and Instruments depending on the Relation of Air to Heat and Moisture, 8vo. By John Leslie, F.R.S. E. Professor of Mathematics in the University of Edinburgh. Mr. Leslie has already gained considerable reputation by his curious experiments on the effect of surface on the rate of cooling or heating, which he published about nine years ago. In the present little tract he gives us his opinions respecting the nature and effects of heat in general; and makes us acquainted with some important facts which he has ascertained respecting evaporation, the dryness and moisture of air, and the mode of producing cold by evaporation. He describes a variety of instru ments which he has contrived for this kind of investigation. The book is written with considerable perspicuity; and, as far as I can judge, the style is greatly preferable to that of Mr. Leslie's other literary productions. No great attention has been paid to accuracy of arrangement; and Mr. Leslie introduces without ceremony (as has always been his habit) any topic which strikes his fancy, whether it bears upon the subject in hand or not. Perhaps the subjects treated of in this work are of so unconnected a nature, that they were not easily susceptible of a better arrangement than our author has given them: but there was a very obvious method of destroying the want of connexion which always looks ill in a philosophical work. The book might have been divided into as many chapters as there were subjects discussed. This would have rendered the whole much more perspicuous and entertaining; and, I am persuaded, would have made the book much more generally read than it will be. In its present state it is best adapted for those who are already pretty well acquainted with the doctrine of heat. Had it been divided into chapters, it would have been easily understood, so perspicuously is it written, by every person in the least curious about such subjects. In my analysis of the book I shall take the liberty (for the sake of my readers) of supplying Mr. Leslie's omission, and dividing it into its various heads. 1. Sketch of the Facts respecting Heat.-Mr. Leslie, with the greater number of philosophers of the present day, thinks that the phenomena of heat are best explained by considering it to be a fluid of a very peculiar nature, either the same as that which produces light, or a modification of it. He gives us a short sketch of the facts known respecting the conducting power of different bodies, and their different capacities for heat. He adopts 135° for the latent heat of water. This is the number which Mr. Cavendish informs us he obtained by his own experiments. From the well-known accuracy of Mr. Cavendish, there is every reason to believe that his number is entitled to be preferred to 140°, the number which Dr. Black deduced from his experiments. At the same time, it were to be wished that Mr. Leslie had informed us of the reason which induced him to adopt 135° in preference of 140°. Did he repeat the experiment himself, and obtain 135°? Or did he rely solely upon the authority of Mr. Cavendish? Mr. Leslie accounts for the heat evolved during combustion by the change of capacity which the substances concerned in combustion undergo. Thus when charcoal is burnt, the oxygen of the air is changed into carbonic acid; and the superiority of the capacity of oxygen gas above that of carbonic acid is the reason of the enormous quantity of heat evolved during the combustion. This is the mode of explanation which was first given by Dr. Black, and afterwards adopted by Dr. Irvine, and Lavoisier, and Laplace. I endeavoured about ten years ago to show that it was quite inadequate to account for the phenomena; and I still consider my arguments as perfectly conclusive. The new experiments of Berard and Delaroche on the specific heat of the gases put the inadequacy of the explanation adopted by Mr. Leslie, and the philosophers just named, in a very striking point of view. The specific heat of oxygen gas is 0.236), while that of carbonic acid is 0.2210: so that the oxygen has a specific heat th parts higher than the carbonic acid. Let us suppose a pound of charcoal consumed. From Lavoisier's experiments it appears that the heat evolved is sufficient to melt 96 lbs. of ice. Now this (supposing Mr. Cavendish's estimate correct) is equal to 13027 degrees of heat. The oxygen consumed amounts to 2.8 lbs. nearly so that each pound of oxygen, when changed into carbonic acid, must have given off 3428 degrees. Here a change in the specific heat amounting only to or not quite d of the whole, occasioned the escape of 3428 degrees. Such a conclusion can only be adopted if we suppose. the absolute quantity of heat in the oxygen gas to amount to 147404 degrees. This supposition exceeds the estimate of Dr. Crawford nearly 100 times; and it is more than ten times greater than that adopted by Dalton. No person can believe that oxygen gas contains so much heat. Of course the supposition that the heat evolved during combustion is owing to a change of capacity merely cannot be defended. If heat be a fluid, it must enter into chemical combination with certain bodies, and the decomposition these combinations must be the cause of the heat evolved during combustion. Mr. Leslie's notions of the capacity of the different gases for heat, as stated in this treatise, are much more accurate than those of his predecessors, though they do not agree with the results obtained by Delaroche and Berard. Thus he makes the specific heat of hydrogen gas about ten times greater than common air. Delaroche and Berard make it rather more than 12 times greater. II. Evaporation. The facts stated by Mr. Leslie respecting evaporation are curious, and some of them are new. What struck me as the most novel and important of his discoveries on this subject is, that the rate of evaporation, like that of the escape of heat from bodies, depends upon the nature of the surface or that the escape of water by evaporation, and the escape of heat from the surfaces of bodies, depend upon the same law. Water evaporates fastest from those bodies that allow heat to escape fastest, and slowest from those that allow heat to escape slowest; and it follows exactly the same rate as the escape of the heat. Hence from the surface of glass, charcoal, or paper, water evaporates much faster than it does from metals. It would appear from this, that it is the radiant heat chiefly that occasions evaporation. Probably the heat that escapes by the conducting power of the neighbouring bodies is acted upon by the affinity of these bodies, and on that account cannot combine with the moisture, and convert it into steam. Another important fact with which Mr. Leslie makes us acquainted is the rate at which the capacity of air to retain |