NATURE 



505 



THURSDAY, MARCH 30, 1899. 



METEOROLOGY IN FRANCE. 



Tfaifc' I'lcmentaire de Meteorologie. Par Alfred Angot, 

 Meteorologeste titulaire au bureau central meteoro- 

 logique. Pp. vi + 412. (Paris ; Gauthier-Villars, 1899 ) 



IN the opinion of the author, meteorology, or more 

 generally the physics of the earth, does not receive 

 in France that study and attention which the subject 

 deserves, both from its inherent interest and its possible 

 usefulness. He traces this indift'erence to the absence 

 of regular teaching in the schools devoted to higher 

 education, to the want of an enlarged professoriate, and, 

 though the statement is not made directly in words, to a 

 deficiency of te.\t-books written with the special object of 

 instruction. He contrasts the devotion that is paid to 

 the study of meteorology in the United States with the 

 apparent carelessness that he perceives in his own 

 country, and offers this book, which is the resume o{ 2l 

 course of lectures he has given in his professorial 

 capacity, to attract more general attention to the subject, 

 and to fill a gap in the scientific literature which his 

 experience teaches him exists. Without the same means 

 of judging of its necessity as M. Angot possesses, we 

 cannot say how far this hope will be realised, but one 

 can have no hesitation in saying that he has offered to 

 his countrymen an admirable treatise, well calculated to 

 serve the ends he has in view. It is well arranged, 

 clearly written, not overloaded with details, either 

 numerical or instrumental, presenting all the facts that 

 are fairly well established, and indicating as far as 

 necessary the lines of future investigation. 



M. Angot divides his treatise into five books, 

 each of which is fairly complete in itself. These books 

 are entitled " Temperature," " Atmospheric pressure," 

 ".■Aqueous vapour," "Disturbances of the atmosphere," 

 and " Weather forecasts." In other words, we have 

 the results of observation followed by theoretical de- 

 duction and practical application. The general plan 

 followed in each of the three first books is to discuss the 

 results of observation as derived directly from instru- 

 ments. These observations disclose the variations that 

 are noticeable throughout the day and throughout the 

 year, each of which comes under examination in turn. 

 The explanation of the several variations follows, both 

 as to amount and time of displacement ; that is to say, 

 both amplitude and phase. This explanation is traced 

 to the general effect of the sun as modified by the action 

 of local circumstances. The plan is very generally 

 adhered to throughout and is satisfactory. It brings 

 clearly before the reader the amount of disturbance that 

 is to be explained, and the efficiency of the causes to 

 explain the results of observation. Of course diagrams 

 and graphical illustration are frequently used, and where 

 it has been necessary to exaggerate eftects in order to 

 make them easily and saliently visible, the scale on 

 which the enlargement has been made is stated. It 

 would be well if this practice were more frequently 

 followed in elementary works ; very erroneous notions are 

 sometimes carried away by students, who remember the 

 NO. 1535, VOL. 59] 



diagrams more perfectly than the letter-press they are 

 intended to illustrate. 



In the determination of temperature, which is the first 

 climatic element considered, the observations, whether of 

 the atmosphere, the soil, or of rivers, are readily made, 

 and the explanation easily traced on general principles. 

 The author writes for those who have only elementary 

 notions of physics and mathematics, so that he some- 

 times states a law and gives its experimental proof with- 

 out entering into a complete mathematical demonstration. 

 This is noticeable in the matter of underground tempera- 

 tures, an interesting subject treated here more fully than 

 in most elementary works, but there is no specia 

 reference to the theory of conductivity of heat. In 

 this course the author is amply justified. In treating 

 of the physics of the earth's crust, it is permissible to 

 assume the results of laboratory and theoretical inquiries 

 into the subject of heat and its diffusion. 



The division entitled atmospheric pressure necessarily 

 includes some general notion of air movements, of baro- 

 metric gradients and of cyclonic disturbances, though the 

 more interesting results arising from the discussion of 

 the behaviour of the atmosphere over areas of high and 

 low pressure are reserved for the penultimate section on 

 the perturbations of the atmosphere. We have in the 

 discussion of the vexed question of diurnal variation of 

 pressure, an instance of the manner in which the author 

 treats subjects that are still more or less uncertain and 

 require further examination. M. Angot prefers to leave 

 the many unsatisfactory hypotheses that have been 

 suggested to explain the cause of this phenomenon 

 severely alone. He is content to say that a complete 

 explanation is still wanting. In his discussion of the 

 observed fact, he follows the explanation originally due 

 to Carlini, and developed by Lamont, of the superposition 

 of two distinct oscillations — the diurnal and the semi- 

 diurnal wave. The latter he leaves where he found it. 

 Into the former, as due to diurnal variation in tempera- 

 ture, the author enters very thoroughly, tracing the modi- 

 fications which are produced by latitude and elevation 

 above the earth's surface. He quotes the observations 

 obtained from barometric readings on the Santis and on 

 Mont Blanc, but makes no reference to Prof. Pickering's 

 measures carried out at elevated stations on the Andes. 



The section on aqueous vapour and of the various 

 forms it subsequently assumes, will be found very inter- 

 esting, embracing all the facts which have been clearly 

 established. We think a little more consideration might 

 have been given to the subject of the action of dust in the 

 atmosphere, both in connection with precipitation and, 

 subsequently, when treating of the optical phenomena of 

 the atmosphere. We should gather that M. Angot is 

 doubtful of the value of much of Mr. Aitken's work, for 

 example. In the sub-section on clouds, some very good 

 illustrations are given. The importance of accurate 

 observation is here and elsewhere insisted on, and we 

 think necessarily ; for notwithstanding recent efforts to 

 inculcate a better knowledge of cloud forms and motions, 

 it will generally be admitted that, except among cloud 

 specialists, uniformity of description and e.xactness of 

 nomenclature are still wanting. The publication of the 

 " International Cloud Atlas," a work on which consider- 



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