progress of meteorology to the rank of a science. This memorable discovery, in disclosing by the elevations and 'depressions of the barometric column what was passing in the more elevated regions of the atmosphere, largely extended our knowledge of this element. It should be further remarked that the value of the barometer as an indicator of the weather gave an additional impetus to the study of the science. 7. The Thermometer.—The invention of the air-thermometer by Sanctorio of Padua in 1590, laid the foundation of a salutary revolution in the science, since it pointed to an exact determination of the temperature of the air, which is by far the most important element of the weather in its relation to our welfare and interests. Improvements were made on the instrument by an Italian artist about 1655, who used wider tubes, terminating in bulbs, and filled with alcohol ; and by Römer, who used mercury, and, starting from the melting-point of ice, divided the tube into degrees, each equal to 100,000th part of the bulb. 8. But the great improver of the thermometer was FAHRENHEIT. He made use of two fixed points in graduating the instrument—one indicated by the melting point of ice, and the other by the boiling-point of water at the mean pressure of the atmosphere. The former point he called 32°, the latter 212o. Any improvements that have since been made in constructing thermometers, such as self-registration, are merely matters of convenience or detail. In so far as concerns the principle, the thermometer may be regarded as having come perfect from the hands of Fahrenheit, for the instrument he invented could be reproduced by any one at pleasure, the indications being in all cases absolutely the same. This great invention soon bore excellent fruit. Small portable thermometers were constructed by Fahrenheit, which, being carried by medical men and travellers over every part of the world, furnished observations of the most valuable description. The comparative temperature of different countries became known, and the exaggerated accounts of travellers with regard to excessive heat and cold prevailing in foreign countries, were reduced to their proper meaning. Thermometers were further turned to excellent account in the arts of brewing and horticulture, and to subjects affecting public health, and thus substantial additions were made to our comforts and luxuries. 9. The Hygrometer.—The expansion and contraction of vegetable and animal substances, according as the moisture of the atmosphere is increased or diminished, would appear to have suggested the idea of the hygrometer, an instrument of great value in meteorology, as indicating the quantity of vapour in the air, at the neral their ence mited the ere. mothe inferentially the changes of weather depending thereon. se substances were used as hygrometers by the earlier meteorists, especially by De Saussure, whose ingenious and exten researches, conducted with the simple hair hygrometer, Etle him to be considered the founder of this department of eorology. 0. From the period of the invention of these instruments, the aber of meteorological observers was greatly increased, and a e body of well-authenticated facts of the utmost value began be collected. The climates of particular parts of the earth e inquired into and compared together; and the science made at and rapid advances by the investigations undertaken by inguished philosophers into the laws which regulate atmoeric phenomena. Important Discoveries and Discussions. 1. The theory of the Trade-Winds was first propounded by on meteors; and the relations of magnetism and the aurora long engaged the attention of meteorologists was Dew. Pictet Geneva, Le Roy of Montpellier, Six of Canterbury, and Patrick Ison of Glasgow, contributed valuable observations and experiats which tended to elucidate the subject. Of these, the first ce is unquestionably due to Patrick Wilson, whose "Memoirs Certain Great Frosts at Glasgow,' about 1780, show a fidelity of ervation, and a skill of interrogating nature, which have rarely n surpassed. When it is considered that he missed the point of ; the argument in continuing to entertain the notion that the cold accompanying dew comes after instead of before its deposition, the genius he manifested in his experiments will appear all the more wonderful. It was reserved for Dr Wells to collect the different observations into a coherent whole, and account for all of them by the theory of dew he propounded—a theory so just and so complete that all succeeding observation and inquiry have only confirmed it. • The Theory of Dew' was published in 1814, and must always be regarded as one of the greatest contributions made to meteorology. The subject of radiation had been discussed by Halley, but his inquiries had reference only to solar radiation, or radiation from the sun to the earth. Radiation outwards from the earth towards space, or terrestrial radiation, was first taken account of by Lambert in his 'Pyrometrie, published in 1779. Prevost of Geneva had also published his “Essay on Radiant Heat' in 1809, or five years before the appearance of Dr Wells's treatise. But as Dr Wells had not seen these tracts, his discoveries regarding radiation were original and independent. Besides, he made this all-important observation or discovery, which neither Wilson nor Prevost had suspected—viz., that during those nights when dew is deposited, the temperature of bodies on the earth's surface is colder than that of the surrounding air. He also ably applied the principles laid down in the essay to explain the production of ice during night at Benares in India. 14. In 1823 Daniell published his Meteorological Essays and Observations,' in which he discussed in a masterly manner the hygrometry of the atmosphere, solar and terrestrial radiation, the barometric measurement of heights, the trade-winds, evaporation, and natural and artificial climates. While in all these departments he contributed largely to our knowledge, his attention was most successfully turned to the investigation of the hygrometry of the atmosphere. Though the practical advantages he anticipated as likely to flow from it have not been realised, yet this difficult, and, in some points, still obscure department of meteorology, is indebted to him more than to any other philosopher. The law of the diffusion of vapour through the air, its influence on the barometric pressure, and its relations to the other constituents of the atmosphere, are among the least satisfactorily determined questions in meteorology. Since this element is so important as an indicator of storms and other changes of the weather, it is to be hoped that it will soon be more thoroughly investigated. 15. A most important addition to our knowledge of the vapour of the atmosphere was made in 1862 by Professor Tyndall of London in his experiments on radiant heat, especially as regards the gases, by which it is shown that the vapour of water exerts extraordinary energy as a radiant and an absorbent of heat. As a consequence, the vapour dissolved in the air serves as a covering or protection to the earth, shielding it from the sun's heat by day, and from the chilling effects of its own radiation during night. It is to be expected that the discovery of the relations of atmospheric vapour to heat will soon be turned to account in explaining many questions of meteorological inquiry. 16. Humboldt's treatise on · Isothermal Lines, published in 1817, mark an important epoch in experimental meteorology. Dovè has since continued the investigation, and in his splendid work ‘On the Distribution of Heat on the Surface of the Globe,' has given charts of the world showing the mean temperature for each month and for the year, together with charts of abnormal temperature. It is scarcely possible to over-estimate the value of this work; for though to some extent the lines are hypothetical, there can be no doubt that a close approximation to the march of temperature, and its distribution over the globe through the year, has been arrived at. The idea has been carried out with greater fulness of detail by the Government of the United States of America, in the beautiful and elaborate series of charts of temperature and rainfall published in "The Army Meteorological Register' for 1855. In these charts, the temperature and rainfall during the different seasons for every part of the United States are laid down from accurate observations. Temperature charts of the British Islands have also been published by the Scottish Meteorological Society, for the months of January, April, July, and October, these months being representative of the four seasons. It is to be hoped, considering how much yet remains to be done in this respect, that societies and governments will undertake the preparation and publication of similar charts, which are of inestimable value, not merely as indicating the climates of different countries, but also as showing how the temperature of one country may, by the intervention of the winds, be affected by the temperature of surrounding countries. The important influence which the temperature of one country, differing materially from that of a neighbouring country at a particular season, has in causing unsettled and stormy weather in both countries at that time, is too obvious to be longer dwelt upon. 17. In connection with terrestrial temperature, the laborious investigations of Dove, Buys Ballot, Jelinek, Quetelet, Hansteen, Kupffer, Forbes, and Glaisher in calculating the mean temperature of places for periods of five or two days, or for each day of the year, deserve to be specially noticed. An examination of these mean daily temperatures brings out the interesting fact that over extensive parts of the earth's surface interruptions occur, at stated times in the year, to the regular rise and fall of temperature, thus pointing to widespread disturbing causes. 18. On the 15th of June 1752, Benjamin Franklin, by the happily-conceived experiment of flying a kite, identified lightning and electricity, thus giving an interest and an impetus to electrical observations. The brilliant discoveries which have recently been made on the mutual relations of electricity, magnetism, heat, motion, and the other forces of matter, lead us to indulge the hope that the application of these results to meteorology will be attended with discoveries equally brilliant and important. Meteorological Societies and Storm-Warnings. ; vala 19. The establishment of Meteorological Societies during the last twenty years must also be commemorated as contributing in a high degree to the solid advancement of the science, which, more than any other, depends on extensive and carefully-conducted observations. In this respect the United States stand pre-eminent, the observers there numbering about 800. Great Britain is also well represented in the English and Scottish Societies, which together number about 150 observers. In Austria, Switzerland, France, Prussia, Italy, Russia, the Netherlands, and other European countries, meteorology is being widely cultivated. In Austria alone the number of stations is 108, and in Switzerland 83. Considerable attention has also been given to the rainfall in Great Britain and Ireland ; and chiefly through the self-denying exertions of G. J. Symons, London, upwards of 1300 rain-gauges are now registering the rainfall of the British Islands. An inquiry has been carried on during the last six years having for its object the determination of the causes which affect the rainfall in the basins of the Rhône and Saône. Obseryers in Germany and Great Britain have been secured to co-operate with the French observers, and under the able management of M. Fournet, important results respecting the rainfall and the progress of storms will be obtained, so that measures may be taken to avert the calamity occasioned by those great floods which periodically carry devastation and ruin over that part of France. 20. A special object of meteorological inquiry is to ascertain the degrees of heat, cold, and moisture peculiar to different localities, and the usual periods of their occurrence, with a view to discover their effects on the health of the people, and on different |