NATURE 



99 



THURSDAY, JUNE ii, 1874 



METEOROLOGY—PRESENT AND FUTURE 



METEOROLOGY has been happily divided by Dr. 

 Balfour Stewart into two great sections, viz. 

 physical meteorology and climatic meteorology.* The 

 object of physical meteorology is to obtain a knowledge 

 of the physics of the earth's atmosphere and surface ; 

 whereas climatic meteorology is properly the practical 

 application of this knowledge in investigating the tempe- 

 rature, humidity, and movements of the air, together with 

 the other atmospheric conditions which make up the 

 climate of a place. 



Owing to the complexity of the subject, the tirst step in 

 meteorological inquiry is to lay down on the globe for 

 each month of the year lines marking out the mean tem- 

 perature, mean pressure, mean wind-direction, and mean 

 rainfall. Roughly approximate averages arc all that are 

 required to begin with in order to mark strongly the broad 

 features of the geographical distribution of these funda- 

 mental elements, from a knowledge of which the guiding 

 principles of future inquiry can alone be safely obtained. 

 Thanks chiefly to the labours ot Dove, Buchan, and the 

 Admiralties of Holland, the United States, and Great 

 Britain, this preliminary information has been collected 

 and placed in a handy diagrammatic form before the 

 public ; not, it is true, with the desired fulness, since con- 

 siderable portions of the globe are still either not at all 

 or very imperfectly represented. Nevertheless, enough is 

 known to form a good basis for future action. 



It is curious to note an undertone running through the 

 works of nearly all writers on climate to the effect that if, 

 for any place, the mean temperature, pressure, humidity, 

 aqueous precipitation, and movements of the atmosphere 

 be stated, its climate is thereby known. Nothing can be 

 more fallacious, the truth being that such information does 

 not enable us to define the distinctive characteristics of 

 any climate. To do this we must have exact observations 

 of, at least, the daily range of temperature, and humidity, 

 the rate of movement of the wind over the place, the drying 

 cjualities of the air, the degree of cloudiness of the sky, and 

 the manner, whether in drizzling or in heavy showers, in 

 which the rain falls. And since the climate of a place 

 cannot be properly defined except by comparison with 

 the climates of other places, absolute uniformity of instru- 

 ments, and their position, and in the methods of observa- 

 tion at different places is indispensable ; for if this be not 

 attended to, their climates cannot be compared. 



Those conversant with the subject are aware how little 

 has really been done towards making comparable and 

 exact observations of atmospheric temperature and hu- 

 midity, and wind, and towards laying down sound 

 methods of discussing the observations so as to deduce 

 results which will define numerically the distinctive 

 features cf climate. For instance, even as regards such 

 striking facts as the arresting of the growth of trees, 

 seen at so many points round the British coasts, we are 

 not yet in a position to say whether the results be due to 

 mechanical, chemical, or more purely chmatic influences. 

 To take a much simpler illustration, no one could venture 



' Nati'RE, vol. i. p. iQi. 



Vol. X. — No. 241 



to institute, on the basis of the temperature observations 

 as at present made in different parts of the British Isles, 

 a comparison of the climates of Shetland and Cornwall, 

 Ayrshire and Kent, &c., in respect of their most essential 

 characteristic, viz. the daily range of temperature, owing 

 to the want of uniformity in the methods of observation. 



In truth meteorology can as yet scarcely be said to 

 have done more than collect the rough materials for 

 future action, or rear the scaffolding for the future build- 

 ing. But the time has surely come when something more 

 ought to be attempted. Researches in physical meteorology 

 ought now to be systematically undertaken, and climatic 

 meteorology prosecuted with more rigorously uniform 

 methods of observation than has yet been done. We 

 shall briefly indicate a few of the more important lines of 

 research to be followed under these heads. 



There is no question in meteorology calling so urgently 

 for extensive, elaborate, and necessarily expensive, experi- 

 ments and observations as that of the vapour of the atmo- 

 sphere. Indeed, upon the right investigation and discus- 

 sion of this element the great problem of weather changes 

 depends. The vapour of the atmosphere as an absorbent 

 and radiant of heat, and the relation of the pure gases of 

 the atmosphere to the solar rays, are questions impera- 

 tively calling for investigation. Intimately bound up 

 with the same inquiry is the temperature of the sky at 

 different heights above the horizon and at diilerent hours 

 of the day, and the temperature of the clouds in connec- 

 tion with their formation and classification — all questions 

 of the utmost importance, particularly in their bearing on 

 the vital subject of terrestrial radiation. 



Continuous observations with reference to the heating 

 and actinic rays of the sun in order to ascertain the law 

 of their periodicity and their relation to the sun-spot 

 period already ascertained, and photographic and spec- 

 troscopic observations of the sun, are also clearly essential 

 to the progress of meteorology, there being an intimate 

 connection between sun observations on the one hand, 

 and meteorology, as well as terrestrial magnetism, on the 

 other. The electricity of the atmosphere also requires 

 special and extensive investigation. 



There is another large and difficult field of inquiry, 

 which yields in practical importance to none, viz. investi- 

 gations by which are sought to be attained the means of 

 valuing scientifically the observations made at stations of 

 the second order, to which alone we can look for carrying 

 out the practical problems of the science in their bearings 

 on health, agriculture, commerce, and other great national 

 interests. Since the observations at these stations are not 

 made by accomplished scientific men or skilled manipu- 

 lators, it is indispensable that the instruments and 

 methods of observation be of the simplest description. 

 Only those refined methods of observation which are 

 consistent with great simplicity are admissible for general 

 adoption at ordinary stations. Thus observations of 

 atmospheric temperature can be carried on at these 

 stations with instruments and methods of observing 

 which are strictly uniform with each other. But a 

 question arises, how near do the results approximate to 

 the true mean temperature of the air at the times of ob- 

 servation ? The answer to this important question can 

 only be obtained by special physical researches under- 

 taken for the purpose. Again, it is highly probable that 



