February 17, 1893.] 



SCIENCE. 



and it is advisable to express as much in the labels as may suffice 

 for a pretty complete knowledge of the objects labeled. If this 

 notion is a correct one, let us welcome the designation of differ- 

 ences in rocks by their names, and not seek to lose sight of these 

 differences in contemplating simply likenesses. On the other 

 hand, it is well to exercise care in the selection of types to be 

 named, so as to avoid as far as possible the lumbering of the ter- 

 minology with needless expressions. Discrimination must, of 

 course, be exercised in the naming of types, and experience must 

 decide as to the value of any proposed name. The writer would 

 prefer that the varietal names should be based upon mineralogi- 

 cal composition, and that adjectives should express the structural 

 differences, where the structure of the variety departs from the 

 characteristic structure of the group. 



CLOUD CLASSIFICATION. 



BY CAPT. DAVID WILSON-BARKER, R N., H.M.S. "WORCESTER," ENG- 

 LAND. 



For some years meteorologists have been in doubt as to the no- 

 menclature of clouds, greatly to the retardment of this important 

 and practical branch of the science. The nomenclature of Luke 

 Howard answered very well for a time, but with our advanced 

 knowledge it scarcely answers at all. It is not simple enough for 

 beginners, nor elaborate enough for those well advanced. Many 

 of the systems proposed lately are simply modifications of this 

 old nomenclature, and retain its faults. Unfortunately, in cloud 

 olassification we are met witli many difficulties at the outset, we 

 -cannot collect and label clouds in a cabinet for reference, but here 

 photography may aid us much. From personal experience it has 

 been found quite possible to portray even the most delicate and 

 fleecy clouds with sufficient accuracy to leave no doubt as to their 

 type. It is proposed in this article to lay before the readers of 

 Science a simple scheme of cloud nomenclature suitable for be- 

 ginners and those unable to devote much time to the study. On 

 this simple scheme can be founded a more elaborate system for 

 skilled nephologists. 



It will soon strike any one who notices weather phenomena ever 

 so casually, that clouds have a tendency to assume one of two 

 well-known forms or shapes, either a heapy or globular form, or 

 that of thin sheets or layers. Clouds in the first form are known 

 as cumulus (cumulus, a heap) clouds. In the second as stratus 

 (stratus, a layer) clouds. Once it is clearly understood that all 

 clouds be divided into these two types as a starting-point, and 

 belong to one or other of these types, the question of a minute 

 sub-division becomes, comparatively speaking, easy. 



It may be well to give here a cloud definition. A cloud is vapor, 

 which has ascended or descended in the atmosphere from a position 

 having a temperature or density greater than the portion of the 

 ■atmospliere it ascends or descends to, which is then unable to retain 

 it in its invisible form. According to the physical state of the po- 

 sition it 7s attracted to, so will be the form it will assume on be- 

 coming condensed. It will be seen from this that the shape of a 

 cloud is more or less determined by its physical surroundings, 

 and consequently it affords a valuable index, not only to the state 

 of the immediately surrounding atmosphere, but also to the 

 weather we may expect, and this frequently some time before any 

 instrumental warnings are indicated. 



Cumulus is essentially the cloud of the lower atmosphere, as, 

 although it sometimes tops to great altitudes, yet its formation 

 commences at a, comparati^'ely speaking, low level. Cumulus 

 clouds assume varied and fantastic shapes, and vary very often 

 from clouds of enormous extent to small nubecules, still there is 

 in them a distinct and marked similarity, which mast be easily 

 recognized. There are three forms of cumulus clouds from which 

 rain falls, viz.: 1. Bold, massive cumulus with feathery tops, 

 which appear to be composed of ice crystals, and are like the high 

 variety of stratus known as cirrus; 2. bold, massive cumulus 

 with all clearly defined borders, only seen in the tropics; 3. fleecy, 

 ill-defined cumulus. The first may be accompanied by either 

 snow, hail, or rain, with a decided increase of wind, and, in fact. 



is a squall, which often gives warning hours before it reaches the 

 observer. In the second is heavy rain with little increase of wind- 

 force, and at sea is the kind of cloud vvhich sometimesaccompanies 

 waterspouts; and the last has only drizzling rain and no increase 

 in wind-force. 



Stratus is formed in all layers of the atmosphere. On the 

 ground it is fog, in the lower atmosphere as covering the sky of ten- 

 times for days in anticyclone areas; in the middle layers in broken- 

 up or more or less circular patches constantly, though erroneously, 

 called cirro-cumulus or cumulo-cirrus, and in the highest layers 

 as the well-known cirrus or curl-cloud. It is the cloud of the 

 finest settled weather, and also of the front of cyclonic disturb- 

 ances, but there can be no mistaking these two conditions. In 

 the former case, it forms a pall over the whole sky, perhaps 

 broken here and there by a rift, through which a blue sky, quite 

 free from other clouds, may be seen, and appearing in all direc- 

 tions in lines parallel to the horizon. The first sign of any change 

 is preceded by the disappearance of this cloud, and the formation 

 of fine threads of cirrus over the sky ; these threads gradually 

 grow closer and closer together until the sun or moon shines 

 through surrounded by a halo. As the cloud gets thicker (seems 

 to grow in the air) this too disappears, rain begins to fall, and a 

 cyclonic disturbance is well under way. In the first case the 

 stratus was in the form of a cloud of great superficial extent and 

 small depth, in the second it has great depth and uniformity of 

 texture. 



Cloud observing is a difficult branch of meteorology, yet no 

 great advances can be made in the physics of the atmosphere 

 until we have a better knowledge of its movements, and this arti- 

 cle is written in the hope that those interested in the subject may 

 not be appalled by the apparently hopeless condition of cloud 

 nomenclature. For if we could have a series of observations 

 taken carefully on even this simple basis, they would be of more 

 value than the majority of observations taken now ; and this 

 especially applies to observations at sea, as it is to the sea we 

 must look for the most valuable meteorological observations. 

 Personal experience has shown that observers, while finding it 

 comparatively easy to distinguish between cumulifotm clouds and 

 stratiform clouds and the different altitudes at which they float, 

 yet often make great mistakes when they have to deal with the 

 subdivisions as they are at present determined. 



NOTES AND NEWS. 



Five lectures on anthropology are to be given on Monday after- 

 noons by Daniel G. Brinton, M.D., LL.D., at the Philadelphia 

 Academy of Natural Sciences, admission free. Tickets can be 

 obtained at the Academy from Dr. E. J. Nolan, secretary. Feb. 

 13, The Bonds of Social Life ; Feb. 20, The Growth of the Arts ; 

 Feb. 27, The Progress of Relit;ions; Mar. 6, Language and Litera- 

 ture ; Mar. 18, Folk-Lore, or the Past in the Present. 



— ■ The Royal Academy of Sciences of Turin announces that 

 the ninth Bressa Prize, consisting of 10,416 francs, will be 

 awarded to any scientific author or discoverer who, during the 

 years 1891-94, shall, in the judgment of the Academy, have made 

 the most important or useful discovery or published the most 

 valuable work ou physical and experimental science, natural 

 history, mathematics, chemistry, physiology, and pathology, as 

 well as geology, history, geography, and statistics. 



— From the American Book Company we have received the 

 four latest volumes of their English Classics for Schools. They 

 are: " Ivanhoe," by Sir Wnlter Scott (484 pages, 50 cents); 

 "Julius Csesar," by Shakespeare (114 pages, 20 cents): "Ten Se- 

 lections from the Sketch-Book," from Washington Irving (149 

 pages, 20 cents); and "The Sir Roger de Coverley Papers," from 

 the Spectator, by Addison, Steele, and Budgell (148 pages, 20 

 cents). The first-named volume is provided with a serviceable 

 glossary, and all are well printed, on good paper, and are neatly 

 bound. 



