دو INTRODUCTORY REMARKS. THE interesting phenomena connected with the science of Meteorology have been found, from very early ages, to excite a lively interest in the human mind. This will occasion no surprise, when we consider how man is placed by nature in a state of dependence upon the various conditions of the atmosphere. To watch their vicissitudes therefore, and speculate upon their consequences, becomes almost a daily necessity. The beautiful scenery produced by the ever varying clouds, consequent upon their state of almost incessant change, contributes very largely to render the science increasingly attractive. Meteorology, considered merely as a source of amusement and recreation, offers many pleasures to those who delight in observing everything which may be passing around them. In every part of the world atmospheric phenomena, with their respective causes and effects, are studied with great interest, whether we consider the electric storm near the equator, or the splendid scenery among the snow and ice of the polar sea. We find that the ancient shepherds of eastern countries, people who were often, if not constantly, abroad both day and night, observed, and some few recorded with a certain amount of accuracy, various atmospheric phenomena. It would appear that to Aristotle should be given the credit of first observing and arranging systematically many natural objects, especially the changes of the weather. He described with accuracy the rainbow, solar halo, and various appearances of the clouds, rain, snow, &c. Shortly after him Theophrastus, the disciple both of Plato and Aristotle, collected and arranged many prognostics of the weather. Most of these prognostics Aratus, the Greek philosopher, introduced into his Diosemeia, while among both Greek and Roman historians are to be found many interesting allusions to the study of Meteorology. The Romans who wrote principally upon this subject were B Pliny, Virgil, Lucretius, and Seneca. Pliny, however, was very apt to indulge in fabulous and often absurd notions; Virgil appears to have followed in the steps and to imitate Aratus; Lucretius labored very much to explain the causes of some atmospheric changes; and Seneca, in his natural questions, endeavoured to give some explanations, which are too lengthy and indefinite to be really interesting. It is remarkable that for many centuries the science should have remained in comparative neglect, when we consider that almost all the operations necessary for the support of human life depend upon various states of that medium in which we live and move and have our being. Little, if anything, was attempted in the way of investigating the great laws of atmospheric changes till the seventeenth century, when certain philosophical instruments were invented, which supplied important desiderata for observing and recording variations. About the middle of the last century, then, the science seemed to revive, and Saussure, Bertholin, Fahrenheit and others stirred up a few scientific men to an attentive study of meteorology. During the present century, and more especially during the last twenty years, the science has made steady and successful progress. The number of careful observers has wonderfully increased, and they are yearly contributing much useful information upon this important subject. In meteorology we should ever bear in mind that it is by recording as much as possible of the past that we are enabled, in a slight degree, to judge of the future; and let me advise those who possess an aptitude for the study of meteorology to cultivate it, not only for their own individual gratification, but for public usefulness. I need scarcely refer to its importance in relation to medicine, for the fact has been fully established that at all times and in all places, the common sense of mankind has ascribed to atmospheric changes the good or bad state of health of the whole human race. The atmosphere and its changes which immediately surround us, and influence to a great extent our daily pursuits and avocations, are really less understood than many other subjects of far less interest and importance. The amount of evaporation from the skin and lungs is entirely regulated by the temperature and humidity of the atmosphere. Both the circulation of the blood and the absorption of food into the body, are accelerated by an increased amount of moisture, which fully establish the medical importance of meteorological enquiries. As another instance of the influence which the amount of evaporation from the body must exert upon the general health, I would state the following from Matteuci's observations, viz.-" That the generality of cutaneous exhalations from the body is sometimes ten times greater in dry than in moist air, and this is doubled in passing from 32° to 64° Fahrenheit." Hippocrates says, in the opening paragraph of his treatise concerning earth, air, and waters, " Whoever desires properly to investigate the art of medicine must do this-first take into consideration the seasons of the year, and how each is capable of operating (on the system), for they not only do not resemble each other, but differ widely the one from the other in the changes (they bring about)," and in aph. i. he remarks "that the changes of the seasons are especially concerned in the production of diseases, and that great alternations from heat to cold and so forth, have also their due effect." Celsus also says near the commencement of his second book, " Sed antequam dico, quibus præcedentibus morborum timor subsit, non alienum videtur expônere, quæ tempora anni quæ tempestatum genera, quæ partes ætatis, qualia corpora maximè tuta, vel periculis opportuna sint, quod genus adversæ valetudinis in quoque timeri maximè possit. Non quòd non omni tempore, in omni tempestatum genere, omnis ætatis, omnis habitûs homines, per omnia genera morborum et ægrotent et moriantur; sed quòd frequentius tamen quædam eveniant; ideòque utile sit scire unumquemque, quid et quando maximè caveat." At the present day so great an importance is attached, and interest taken, in the science of meteorology, that competent men are engaged in almost every civilized portion of the globe in observing, recording, and investigating the more common atmospheric phenomena. The results of such enquiries cannot be too highly appreciated. During the late war with Russia how many hundreds of valuable lives might have been saved had the climate of the Crimea been more thoroughly understood. I consider that by climate is meant the temperature of the air near the surface of the earth, which, if not entirely influenced by the heat of the sun, is at least greatly dependent upon it. Temperature is found to be very unequally distributed over the globe on account of the various conditions which regulate the distribution of solar heat. 1st. From day to day and from season to season, by the earth's rotation. 2nd. By the degree of latitude of any given place. 3rd. By the distribution of land and water, places on the sea coast being less liable to sudden and great fluctuations of temperature than those situated more inland. 4th. By the character of the soil and colour of its component parts. This is a most important condition, and one too frequently overlooked; for certain soils have a marvellous power of absorbing and radiating the heat of the sun's rays. 5th. By the elevation of the land above the level of the sea. All these conditions are incessantly influencing the climate of every portion of the earth's surface, and have a tendency so to dissipate and counteract the solar heat, that they can only affect the earth's surface, not its mass, while at the same time they regulate the amount, character, and distribution of animal and vegetable life. Some years ago, Sir John Leslie ascertained, by carefully conducted experiments, that the difference of temperature of the earth during summer and winter at the depth of one foot, amounted to three degrees, while at eight feet it was only half a degree; at one foot from the surface January was the coldest month and July the hottest; but at the depth of four feet March was the coldest and September the warmest. The heat of the sun, therefore, affects the soil to a very limited depth. Further experiments upon the same subject, made at the Paris Observatory, fully established the above facts, and it was also ascertained that there is a point at which the temperature remains constantly the same, and uninfluenced, therefore, by external causes. It has become a well ascertained fact that the climate of places situated not far distant the one from the other varies considerably. The works of Howard and the system of observation so long taken at the Royal Observatory at Greenwich, give a very complete account of the climate of London and its vicinity, and it is at the request of scientific friends, impressed with the desirability of placing all meteorological facts on permanent record, that I have been induced to tabulate and arrange, on the follow |