7 6 



NA TURE 



[Nov. 27, 18 8 



the front than in the rear of a cyclone, where indeed the 

 motion of the cirrus cloud approaches the direction of 

 the lower clouds and of the wind at the surface of the 

 earth. The direction of the cirrus immediately behind 

 and over the centre of depression is in Sweden generally 

 from north or west, but, from the exceptions which occur, 

 it is evident that more observations and discussions of 

 the results are required. 



Fog is of most frequent occurrence when the gradient 

 is directed towards the north and least frequent when 

 directed towards the south. In the Kattegat, fog attains 

 its maximum frequency in the region situated between 

 the lowest and the highest pressures. At Upsala the 

 clearness of the air is nearly independent of barometric 

 pressure, there being, however, a greater tendency to mis- 

 tiness in the air when the gradient is directed towards the 

 west than other directions. Cloud and rain are most 

 frequent with gradients to the south or west, and least 

 with gradients to the north-east. In summer, they regu- 

 larly diminish as pressure increases ; but in winter, less 

 regularly, inasmuch as the strato-cumulus, which are the 

 most common clouds in this season, are most numerous 

 in times of high pressure and occasionally bring with 

 them slight showers of snow. 



In winter, temperature is above the mean both in 

 cyclones and anticyclones when the gradient is directed 

 towards the west, and below it when directed towards the 

 east. In the same season, temperature rises on all sides 

 towards the centre of the cyclone ; in other words, the 

 thermometer rises as the barometer falls, and vice versa. 

 In winter also temperature is ordinarily above the mean 

 in cyclones, but under it in anticyclones and in the 

 region between two cyclones ; in summer the reverse 

 holds good— these results being due to the different 

 effects of solar and terrestrial radiation in these seasons. 



With reference to the distribution of temperature with 

 height, Hildebrandsson has examined the observations 

 made at the Puy-de-D6me and at Clermont Ferrand, 

 near the base of the mountain in connection with the 

 cyclones and anticyclones in that part of Europe during 

 1877-82. The difference between the temperatures of the 

 two places in winter attains the maximum in the vicinity 

 of the centre of a cyclone, and the difference diminishes 

 according as the barometer rises, and the minimum is 

 reached near the centre of the anticyclone, where tem- 

 perature on the mean is higher at the higher station, the 

 difference in height being 3516 feet. In such investiga- 

 tions, this high-level station, as well as the high-level 

 stations in the south of France, in Switzerland, and 

 Austria, have the disadvantage of being almost always on 

 the north-west slope of anticyclonic areas, the centres of 

 which are situated in a south-westerly direction. It is on 

 rare occasions that well-marked cyclones cross these 

 stations, and still rarer that cyclones pass to the south- 

 west of them. Prof. Hildebrandsson states his opinion 

 that, for the prosecution of these all-important researches, 

 lien Nevis, with its low- and high-level stations, occupies 

 whal is, perhaps, the most favourable position in the 

 world, seeing that it is situated in the track of the greater 

 part of the Atlantic storms which sweep over North- 

 Western Europe, and that the publication of the 

 observations in extenso would be an important gain to 

 science. 



" FLATLAND" 

 Flatland: a Romance of Many Dimensions. With Illus 



nations by the Author, A Square. (London : Seeley 



and Co., 18S4.) 

 ■\ A7"E live in an age of adventure. Men are ready to 

 join in expeditions to the North Pole or to the 

 interior of the African continent, yet we will venture to 

 say that the work before us describes a vast plain as yet 

 untrodden by any Fellow of the Royal Geographical 

 Society, and teeming with a population of which no 

 example has figured in any of our shows. A few years 

 ago a distinguished mathematician published some specu- 

 lations on the existence of a book-worm " cabin' d, cribb'd, 

 confin'd " within the narrow limits of an ordinary sheet 

 of paper, and another writer bewailed " the dreary in- 

 finities of homoloidal space." A third remarks, " there 

 is no logical impossibility in conceiving the existence of 

 intelligent beings, living on and moving along the surface 

 of any solid body, who are able to perceive nothing but 

 what exists on this surface and insensible to all beyond 

 it." How delighted Prof. Helmholtz will be to find, if 

 this Flatland writer is worthy of credence, his conjecture 

 thus verified. " Flatland " is not the real name of this 

 unknown land (that secret is not divulged), but it is so 

 called here to make its character clear to us Space- 

 denizens. It is a noteworthy fact that one at least of the 

 Flatlanders expresses himself in remarkably correct 

 English, and singularly after the manner of an ordinary 

 Space-human being ; and further, though — we regret to 

 have to record it — as a martyr in the cause of the truth of 

 a third dimension, he has spent seven long years in the 

 State jail, yet these memoirs have in some mysterious 

 manner found their way into our hands. There is hope 

 then that some one of our readers may yet expatiate in 

 the broad plain, though the penalty will be, we fear, that 

 he must first become as flat as a pancake and then see to 

 it that his configuration (as a triangle, square, or other 

 figure) is regular. This latter is a sine qua nou in Flat- 

 land, because, whatever you are, your configuration must 

 be regular, or woe betide you, and you will shuffle off your 

 mortal coil incontinently. 



We will not stop to inquire how this and that have 

 come about, but will endeavour to lay before our readers 

 some of the features of this (to us) new world, though we 

 are informed that it has just entered upon its third 

 millennium. 1 



In Flatland there is no sun nor any light to make 

 shadows, but there is fog. This, which we on this earth 

 consider to be an unmitigated nuisance, is recognised in 

 that other world " as a blessing scarcely inferior to air 

 itself, and as the Nurse of Arts and Parent of Sciences." 

 If there were no fog, all lines would be equally distinct, 

 whereas under present circumstances, " by careful and 

 constant experimental observation of comparative dim- 

 ness and clearness, we are enabled to infer with great 

 exactness the configuration of the object observed." It 

 is a necessity of Flatland life to know the north (for 

 instance, it is a point of good breeding to give a lady the 

 north side of the way) ; this is determined in the absence 



1 From the secret Archives it appears that at the commencement of eacli 

 millennium a Sphere descended into the midst of the Council of Circles pro- 

 . I. liming the great truth for the attempted teaching of which our author is in 



