222 



NATURE 



[July 6, 1882 



discover the antidote for snake-bites, you'll have a cure for 

 yellow jack ! " Arthur Stradling 



29, Woodford Road, Watford, Herts 



The Rainfall of the Globe 



In reference to a paragraph in an article on the rainfall of the 

 globe in Nature, vol. xxvi. p. 206, Prof. Loornis states that 

 the heaviest rainfall is met with in the rain belt, which surrounds 

 nearly the whole globe lying between the north-east and south- 

 east trade-winds. 



Having been engaged in collecting records of rainfall at sea 

 for some time back, 1 may take the opportunity of saying that I 

 have received data enough to enable me to give an estimation of 

 rates per annum for this rain-belt. 



That for the Atlantic Ocean is calculated at 133-37 inches 

 per annum, that for the Indian Ocean at 80-55 inches per annum, 

 that for the Austro-Chinese Seas at 107-96 inches ; but none has 

 vet been made out for the Pacific Ocean, owing to absence of 

 observation altogether from that quarter. 



In physical atlases the rain-belt is continued across this ocean 

 in the same latitudes as it is found to exist in the Atlan'ic and 

 Indian Oceans, but as yet it is only conjectural, and it may prob- 

 ably be found to cross in other spaces by direct observations 

 taken at sea. The observance of rainfall on islands in the open 

 oceans would appear to afford but imperfect means of judging of 

 the rainfall at sea surrounding them. It is frequently found that 

 they differ very materially, as at St. Helena, the island may be 

 covered with mists, invisible, while the ship outside is sailing 

 under a clear sky and fresh breeze. 



The ocean rainfall, therefore, can only be made out by obser- 

 vations on board ships, and these are not easy to get, and also 

 take up a long time in effecting. W. ]. Black 



Caledonian United Service Club, Edinburgh 



The Recent Unseasonable Weather 



Mr. Archibald's letter on this subject displays great ability, 

 and is deserving of much attention by meteorologists. Nothing 

 can be, I think, more interesting and important than a proper 

 interpretation of the meaning of the facts of the weather of the 

 late extraordinary and contrasted seasons. Will you, therefore, 

 allow me shortly to make a few remarks regarding the com- 

 parison pointed out by Mr. Archibald as existing between the 

 weather of India and that of North Europe. 



In the " Report on the Meteorology of India," 1S77, the 

 reporter, referring to the Himalayan regions, says: "There are 

 two periods of cold, (1) when the snow is accumulating ; and (2) 

 when it is dissolving ; and the first occurs in January and Feb- 

 ruary, the latter in April and May." Again, he says: "The 

 conclusion appears to be very strong that during the early months 

 of the year, one very important factor in determining the pe- 

 culiar features of the season i~, the amount of snowfall and of 

 snow accumulation in the Himalayan regions during the winter." 

 For six years past I have observed the same thing hold gene- 

 rally in the north of Europe, a cold winter being followed by a 

 late spring and an ungenial summer, and vice versa. This I 

 would therefore be inclined to regard as a general law. The 

 weather of June, however, serves to indicate the difference be 

 tween the meteorological conditions of India and North Europe. 

 It has been ungenial, I think, solely, on account of the excep- 

 tional force and warmth of the winds of winter causing a vast 

 detachment of the ice in the polar regions. This ice has floated 

 into lower latitudes — has come much nearer to us — and has 

 produced, in melting, icy winds. These commingling with the 

 warmer tropical winds, have produced in their turn the recent 

 changeable weaiher. 



Our cold spring winds usually come from the east of north, 

 but the prolongation of cold winds which we experienced in the 

 middle of June, came from the we-t of north, indicating their 

 origin to be in the masses of ice floating for the most part 

 probably between Iceland and the American coast. Thus the 

 movable ice has caused a high atmospheric pressure and a low 

 temperature. The fixed ice, however, which forms by far the 

 largest area within the Arctic Circle, has been during this winter 

 relatively diminished, and from it, therefore, we should expect 

 less incursion of cold winds ; therefore a finer summer. 



While, then, the chief influence of warm westerly winds in 

 winter is, as I believe, to produce a fine summer, their minor 

 influence must be, particularly when strongly developed, as they 



have been during the past winter, by detaching an unusual 

 quantity of Arctic ice, to produce unseasonable v\ eather in early 

 summer. 



The same exception would take place in India, if we could 

 suppose some part of the winter's accumulation on the Hima- 

 layas to be carried at the close of a severe winter down into the 

 northern plains so as to distribute in melting, volumes of cold air 

 throughout the otherwise warm atmosphere. 



Dundee, July 3 Davjd Cunningham 



Is the Axis of a Cyclone Vertical? 



I AM not aware if it has ever been suggested, in explanation 

 of the frequent (or rather, usual) incompleteness of cyclonic 

 disturbances, that the axis of the cyclone may be inclined, and 

 consequently only one side of the disturbance affect the earth's 

 surface, the other half being at a greater or less elevation, 

 according to the amount of the inclination, and thus (so far as 

 wind currents are concerned at least) lost to us. 



My own observations of storms in this country point to a 

 southerly inclination of the cyclonic axis. I should be glad to 

 know if observers in the southern hemisphere have traced any 

 indications of a northern inclination in the cyclones there. 



J. A. Westwood Oliver 



Eelle Vue, Springburn, Glasgow, June 25 



The idea propounded by Mr. Oliver, that the axes of cyclones 

 are inclined, is no new one, nor is it the fir.^t time that a southerly 

 inclination has been inferred to exist, to account for the prepon- 

 derance of winds belonging to the southerly quadrants, and the 

 comparative absence of those belonging to the northerly quad- 

 rants of cyclones in our latitudes. 



The value of Mr. Oliver's opinion on this point must depend 

 to a great extent on the nature of the observations on which he 

 relies. 



This supposed southerly inclination was formerly attributed 

 by Andrau and other Dutch writers (according to Reclus), to the 

 fact that a cyclone, starting from some point near the equator, 

 must have its rotation-axis initially inclined to the terrestrial 

 axis nearly at right angles, and that as it moves from thence pole- 

 wards, the direction of its rotation-axis remaining fixed in space, 

 it must apparently become gradually more and more inclined to 

 the local horizon in a southerly direction. This explanation is 

 ingenious, but there are many considerations, both theoretical 

 and practical, which militate powerfully against it. 



Another view — that of the Rev. W. Clement Ley, derived 

 from observation (principally of the upper clouds) — makes the 

 axis of a cyclone incline backwards as reganls its direction of 

 translation, and in favour of this notion, the retardation in the 

 occurrence of the barometric maxima and minima on the summits 

 of Mount Washington, Pike's Peak, and Mount Michel!, noticed 

 by Prof. Lcomis, has been cited. 



Ferrel, however, remarks that "a retardation of just about the 

 same amount is observable in the occurrence of the times of 

 maxima and minima in the diurnal changes of the barometric 

 pressure at the summits of these same mountains, which cannot be 

 explained by means of cyclones with reclining axes," so that in 

 all probability the same cause acts in both cases, and is inde- 

 pendent of any such special quality of cyclones as that inferred 

 by Mr. Ley. 



The hypothesis of Mr. Ley is, moreover, so much at variance 

 with mechanical principles and with what we should naturally 

 infer would take place, that, as Mr. Ferrel says, "we must 

 hesitate to adopt it, without seeking further for some more 

 plausible hypothesis to explain the observations." 



The theory of cyclones, as developed by Ferrel and others, 

 makes it far more probable that if there is any inclination at all, 

 it will be small, and forwards, not backwards. 



Ferrel thinks it possible that the elliptical form of the isobars 

 and rain-ateas is partly due to this forward inclination of the 

 axis. 



Moreover, the preponderance of southerly and westerly winds 

 in our cyclones cannot correctly be adduced as an argument in 

 favour of the southerly inclination of their axes, since it is mainly 

 due to the fact that our cyclones are for the most part secondaries, 

 moving within the periphery of a large, nearly permanent 

 cyclone, H hose centre generally lies not far from Iceland, and 

 thus those winds and gradients predominate, which would tend 

 to occur in that part of the large cyclone where we happen to 

 be situated. E. Douglas Archibald 



