ing the temperature, wind, barometer, and weather, and the condition of the sea for the region within about five hundred miles of London. This chart is prepared daily by the London Meteorological Office, and furnished gratuitously to the newspapers. The stereotype plate, fit for use in a Walter printing-machine, is produced in about an hour. It is now more than four years since a similar undertaking, on a somewhat different scale, was set on foot by Sir William Mitchell in the Shipping Gazette of London, and which has been continued daily. CONNECTION OF WEATHER AND COLLIERY EXPLOSIONS. Messrs. Scott and Galloway, of England, have continued their researches into the connection between colliery explosions and the weather. As the result of the study of two hundred and twenty-four explosions, they state that the amount of fire-damp recorded in the mines increases and diminishes directly as the barometer falls and rises, proving beyond the possibility of cavil that the variations of atmospheric pressure have a marked influence on the rate at which fire-damp escapes from fissures. In the large majority of the fatal explosions the miners were using naked lights; and they suggest that if fire-damp is known to be present in any part of the mines, then either the workmen should not be allowed at any time to be near it, or else they should use safety-lamps in its vicinity, at least during the continuance of the barometric depressions. They also suggest the interest and value that would attach, both in a scientific and a practical point of view, to the keeping at coal-mines of baromet ric records, such as are daily furnished by the self-recording apparatus which can now be obtained from every meteorological office.-Quart. Jour. Met. Soc., London, II., 195. THE HOURLY DISTRIBUTION OF RAINFALL Among the very few meteorological stations at which the rainfall has been recorded either continuously or hourly is to be noted that of Berne, in Switzerland, the observations at which place for the past eight years have recently been studied by Forster. The diurnal periodicity of rainfall, both as regards its quantity and its frequency, follows at this place a regular law, and, on the average of the year, it is shown that the probability of rain increases from one o'clock in the morning to a maximum at seven o'clock in the morning, then sinks to a minimum at two o'clock in the afternoon, and rises again to a maximum at midnight. The diurnal period is thus almost opposite to that which obtains under the tropics, where in the afternoon, at the hour at which the temperature is at its maximum, and at which the clouds are, on the average, the highest above the earth, it rains most frequent ly.-19 C, VII., 234. PERIODICITY OF SEVERE WINTERS. A memoir by Rénou, the distinguished French meteorolo gist, upon the periodicity of severe winters, although published many years ago, has been recently quoted in defense of the opinion that such periodicity actually exists. According to Rénou, rigorous winters return about every forty-one years. They are arranged in groups, generally composed of a central winter, and four or five others disposed on either side of it, within a space of twenty years. Mixed with these years are others, also, of unusual warmth, in such a manner that the mean cold of the season is not sensibly altered. The period of forty-one years seems to be that which corresponds to the maxima of the solar spots at the same season of the year. A central cold winter arrives eighteen months after the maximum of spots has coincided with the warmest season of the year. The severe winters seem to alternate between the northern and southern hemispheres of the earth. -13 B, 135. ORIGIN OF THE CENTIGRADE THERMOMETER SCALE. According to the historical notes contained in the meteorological observations of Lafou, president of the Meteorological Commission of Lyons, the first thermometer that was ever seen at Lyons was brought thither in February, 1736, by Duhamel, to Father Duclos, director of the observatory founded by the Jesuits in the chapel of their college. This thermometer was constructed with alcohol, according to the principles of Réaumur, and was used for some time. A member of the Academy of Lyons, named Christin, replaced the alcohol by mercury, as had, indeed, previously been done by Fahrenheit in 1724, and by Dr. Sauvage at Montpelier in 1736. Christin having introduced into a tube terminated by a bulb a quantity of mercury, whose volume might be represented by 6600 at the temperature of freezing water, found that this volume became 6700 when the tube was plunged into boiling water. The alcohol of the original thermometer being thus dilated 100 parts, Christin divided the corresponding space passed over by the mercury into 100 equal parts, remarking that these new divisions, being smaller than those of Réaumur, would be more in harmony Iwith the sensations caused by variations of temperature. Such was the origin of the Centigrade thermometer, which was afterward known for a while under the name of the "Thermometer of Lyons." Four years after-that is to say, in 1746-Cassini, who was a well-known optician at Lyons, had sold seven hundred of these in Paris, besides others in Provence and Dauphiny.-13 B, III, 94. PERIODICITY OF HAIL-STORMS. The tendency which has been so marked of late years to look for a periodicity in almost every natural phenomenon corresponding to the periodical increase and decrease of the solar spots, seems to have been carried to its fullest extent in the recent suggestion of Professor Fritz, according to whom the frequency of hail-storms has some connection, accidental or otherwise, with the frequency of solar spots. He finds, by collecting the records from twenty-five different European and other stations, that all observations show that the years of greatest frequency since 1806 have been 1817, 1830, 1838, 1848, and 1860, which years follow or are nearly coincident with the sun-spot maxima of 1817, 1829, 1837, 1849, and 1860; whence it would follow that the year 1871, a year of sun-spot maximum, should be also a year of frequent hail-falls, as actually was generally recorded. Furthermore, seasons of infrequent hail-storms correspond to the minimum of solar spots, as in 1810, 1823, 1834, 1844, and 1856. It has also been often remarked that a winter of extensive or frequent auroras is followed in the succeeding summer by unusual hail-storms. The connection between auroras, lightning, hail, and cirrus clouds and the solar spots seems, therefore, worthy of further study.-7 C, XV., 244. FIGURES MADE BY LIGHTNING. Professor Tomlinson, in writing on the subject of the figures or marks left on the bodies of men or animals killed by strokes of lightning, states that very instructive tree-like figures may be produced on sheets of ground glass by passing over them the contents of a Leyden-jar. These figures, like those on the human subject, are not derived from any tree whatever, but represent the path of the lightning itself. This subject has been studied by numerous authors; among others by Poey, who, in 1861, published a small volume, in which twenty-four illustrative cases are cited. He accounts for their formation as a photo-electric effect, in which the surface of the animal is the sensitive plate, the tree, etc., the object, and the lightning the force that impresses it. Among many remarkable cases that can be quoted was one that occurred at Zante, where the mast of a vessel was struck, and a sailor sleeping in a cot on the deck was killed. The number 44, in metal, was attached to the fixed rigging between the mast and the cot. On the left breast of the dead sailor was found the number 44 well formed, and perfectly identical with that on the rigging. Light was thrown upon these cases by Mr. Varley, who, noticing some specks on the metallic ball of the positive pole of a Holtz electric machine, tried to wipe them off with a silk handkerchief, but in vain. He then examined the negative pole, and discovered a minute speck corresponding to the spots on the positive pole. It was evident that lines of force existed between the two poles, by means of which, as it were, telegraphic communication was made from one to the other; and in explanation of the marks made on the human subject, it is stated that a lightning burn on the skin is produced whenever the object struck is electrically positive to the metallic object, the discharge itself being a negative one. CLIMATOLOGY OF FLORIDA, In an address on the climatology of Florida, recently delivered by Dr. Baldwin, the author gives some interesting statistics, whose value is indicated by the fact that they are based upon thirty-six years' meteorological observations, recorded by himself, at Jacksonville, together with numerous shorter records from the stations in other portions of the |