495 



KDomledge & Selentifle Hems 



A MONTHLY JOURNAL OF SCIENCE. 



Conducted by MAJOR B. BADEN-POWELL, F.R.A.S., and E. S. GREW, M.A. 



Vol. III. No. 21. [new series.] AUGUST, igo6. 



C Entered at -i 

 Stationers' HallJ 



SIXPENCE NET. 



CONTENTS-^See page V. 



Cloud Photography. 



By William J. S. Lockver, .\1.A., rii.D., F.R.A.S. 



Who has not sat on the grass or a bench on a hot 

 summer's afternoon and turned his head skywards and 

 watched the ever-restless clouds wafted along by the 

 aerial currents ? 



Who, also, has not had his attention drawn to a 

 towering cumulus cloud mounting up and up into the 

 higher regions of the atmosphere and preparing Itself 

 for a possible exhibition of atmospheric electricity, in 

 the form of a thunderstorm ? 



Latent energy, grace, beauty, to say nothing of the 

 exquisite gradations of shade, are all present in those 

 masses of water-vapour or ice-crystals, and it is really 

 surprising what little attention they receive, even at'the 

 hands of the photographer, except possibly for an oc- 

 casional casual remark. 



To the meteorologist of to-day the study of clouds 

 has assumed an important part of his work, for oy 

 their movements and changes of form, the inner work- 

 ings of the upper air currents can be, to a certain ex- 

 tent, watched. This must be so' for a long time to 

 come, as the employment of kites and ballou-sondcs does 

 not yet allow us to reach at short notice such elevated 

 regions; clouds are therefore the only means we have 

 for nearly continuous observation at great altitudes. 



The part played by the photographer is tO' record, for 

 later study if necessary, the forms and types of cloud 

 The camera thus affords the means of making a classifi- 

 cation of clouds more complete than was previously 

 the case, in addition to presenting us with a most inter- 

 esting pastime. 



One decided advantage of clouil photographv o\er 

 many other photographic pieces of work, is that it can 

 be piu\sucd wherever the photographer happens to he 

 Clouds we have nearly always with us, and sometimes 

 we think much too often, and the upper storey or roof 

 of a house, failing a better position, affords an excellent 

 place to work from. 



One of the first cloud classificaticns w;is put forward 

 by Luke Howard in 1805;, and up to quite recently 

 this has held first place. ^L'^ny other attempts in the 

 meantime have been made at a more scientific classifi- 

 cation, and most, if not all of them, with the exception 

 of tiiat of Clement Lev, were simply makeshifts. Lev's 

 classification is undoubtedly long, and is not well fitted 

 for use except by professional investigators or tliose 



amateurs who wish to take up the subject of nephology 

 thoroughly, and have plenty of time at their disposal. 

 During more recent years, an attempt has been made 

 to draw up a more simple and efficient system and that 

 which is now being adopted is termed the " International 

 System of Cloud Nomenclature." 



There is, however, quite a large literature on cloud 

 classification and cloud photography, but it is not my 

 intention tO' pass this in review in this article. It may, 

 howe\er, serve a u.seful purpose to draw the reader's 

 attention to several publications on this subject, if he 

 ;:hould wish to dip more deeply into this interesting 

 study. 



The " International Cloud .Atlas,'' to which reference 

 has just been made, has text in English, French, and 

 German, and is published by Gauthier Villars, in Paris 

 (18961. The Hydrographic Oflice at \\'ashington has 

 published (1897) an atlas illustrative cf cloud forms 

 which includes 16 coloured plates. 



Quite recently, Mr. A. W. Clayden has published a 

 valuable contribution in his book on '" CJoud Studies" 

 (John Murray, London, 1905), and this contains a great 

 number of photographic reproductions from his nega- 

 tives. 



In this Journal numerous illustrated articles have 

 appeared from time to time on the progress of cloud 

 photogr.-iphy. Thus, for instance, E. M. ,\ntoniadi 

 (Vol. XIV"., p. 202 and \'ol. X\'., pp. 79 and 107); James 

 QuickC (Vol. XI\"., p. 103); Wilson Barker (Vol. X\'II., 

 p. 104); and H. C. Russell (.August, 1894), ha\e all con- 

 tributed much information, which should be consulted 

 by tha photographer. 



Other valuable contributions to cloud literature in- 

 clude'' Instructions for Obser\ing Clouds," by the Hon. 

 Ralph .Vbercromby (London, 1888); " The Cloud World" 

 (Elliot Stock, London, 1903), bv Samuel Barker; "La 

 Photographic el I'etude des Xuages'' (Mendel, Paris, 

 1898), i)v Jacques Bayer; and .several works and articles 

 by Hildebrandson, Koppen, Xewmeyer, Clement Ley, 

 .'\ngot, Tisserenc de Bord, Flammarion, &c. 



'fhe above references will, no doubt, serve to draw 

 the reader's attention to some of the work that has been 

 accomplished, and he will soon be able to extend this 

 list for himself when he becomes better acquainted with 

 the subject. 



For the purpose of this article, only the two main 

 clas.S'Ss into which clouds may be divided need be men- 

 tioned. The first is the "cumulus" form of cloud, 

 which is formed by vertical convection, that is, the air 

 is transported from one level to another. Tlie second 

 main class is the " stratus " cloud, which is generally 

 the result of the flowing of two currents of air over each 

 other, the temperatures being different in the adjacent 

 layers. 



The former type indicates an attempt to restore 



