Feb. lo, 1 88 1 J 



NATURE 



337 



Benvenuto Cellini was attracted to Paris fmm I'lorence in conse- 

 quence of the much clearer and morebeantiful atmosphere in the 

 capital of France than in Italy ! This fact is derived from the 

 artist's autobiography. What a charge now ! Paris is rapidly 

 becoming as bad as London. W. II. Preece 



February 5 



In Nature, vol. xxiii. p. 195, I found an interesting abstract 

 of a paper read to the Royal Society of Edinburgh, December 

 20, by Mr. John Aitken, showing "that dust is the germ of 

 which fogs and clouds are the developed phenomena." It is not 

 in the least the intention of this letter to diminish the value of 

 the above-mentioned paper and experiments, but I wished to 

 say that already, several years past, the same results were obtained 

 by Messrs. Coulier and Mascart (1S75) in France (NahtrforscJur, 

 1875, p. 400; journal de Pharmacie et de Chimie, serie 4, xxii. 



P- "^5)- , , „ . , 



In my " Theorie cosmique de 1 Aurore Polaire, p. 36, I 

 have already pointed out the great importance of these results 

 on the relation between aurora? and clouds and the danger of 

 measuring the height of auroral displays by means of superior 

 cloudy apparitions (p. 35). In fact, if the invisible aqueous 

 vapour is able to reach much higher regions than terrentrial dust, 

 and if aurora; are in close connection with cosmical matter in a 

 state of extreme division, lilsC our theory attempts to prove, this 

 cosmical matter is without any douht enaliled to form aqueous 

 clouds in a much higher than tlie usual level. Moreover we have 

 already, in 1S73, i" ^^ German journal Gaca (Koln und Leipzig, 

 E. H. Mayer), asked : " Welches wohl die weitere Rolle der 

 Eisen- und anderen Dampfe sei, welche nach der Verbrennung in 

 den oberen Regionen der Atmnsphare schwebend bleiben und 

 oflenbar nach vollstiindiger Abkidilung einen Niederschlag von 

 fein vertheiltem Eisenoxyd und anderen Stoffen bilden. SoIIten 

 diese Theilchen . . . keine Veranlassung geben konnen zu den 

 von deutschen Beobachtem so oft wahrg nommenen ' Polar- 

 bandem,' ' deren Zusammenhang mit dem Nordlicht schon ofters 

 dargethan ward, aber bisher unerklart blieb. Noch wiirden wir 

 hinzufiigen konnen, mit Hinweis auf die Beobachtung Secchi's 

 eines angeblichen Nordlichts bei Tage (Nature, October 17, 

 1872), dass auch die bis jetzt ganz unerklarte, eigentbiimliche 

 Gestalt der Cirri, mit ihren ganz regelma-sigen, auf ein gewisses 

 Gesetz hindeutenden transversalen Verzweigungen, von der 

 Anwesenheit feiner Eisen^taubkerne in den Eisnadeln mo licher- 

 weise bedingt ist. Bekanntlich schweben ditse Cirri in den 

 hochsten Wolkenregionen." 



It will further be generally known that microscopic meteorites 

 have betn found in the centre of hailstones (Comples rtndus, 

 1872, p. 683). H. J. H. Groneman 



Groningen (Netherlands), January, 1881 



New Cases of Dimorphism of Flowers — Errors 

 Corrected 



Reviewing my notes and drawings of some ye.irs ago, I find 

 the following new cases of dimorphism of flowers : — 



1. Sytinga persica, L., cultivated in the garden of the Lipp- 

 stadter Realschule, is gynomoncecious. In the same inflor- 

 escence there are found a m.ajority of hermaphrodite flowers of 

 larger size and a minority of female flowers of smaller size. The 

 hermaphrodite flowers are homogamous and short-styled, like 

 Syringa vulgaris, L. (H. Miiller, " Die Befruchtung der Blumen," 

 p. 340, Fig. 125). The anthers of the female flowers, which 

 are much reduced in size and never contain any pollen, are 

 inserted sometiites above, sometimes beneath, but commonly in 

 the same height with the stigma. In some few of the small- 

 sized flowers the number of the petals is reduced to three. 



2. StcUaria glauca^ L., near Lippstadt, is gynodicecious, like 

 St. gi-aniinca, I,., as described by F. Ludwig {Bol . Centralblatt, 

 No. vi. p. 28), some stems bearing small-sized flowers with very 

 reduced anthers of white colour and greatly-developed stigmas, 

 a vast majority of other stems bearing larger-sized proterandrous 

 flowers with anthers of red colour. 



3. Sherardia arvensis, L., near Lippstadt, is likewise gyno- 

 dii-ecious, its hermaphrodite flowers being proterandrous and 

 larger-sized, with a corolla of 3j-4mm. diameter, its female 



^ Or " Polarbanden." My daily observa 

 beginning with the year 1875, are to be fj 

 IVochenschriftt editor. Dr. Hermann J Klein i 



phenomena, 

 ■man journal 



flowers possessing a corolla of only 2^-3 mm. diameter, with 

 extremely reduced anthers. 



4. Aspcrida tincloria, L., produces in Thuringia so frequently 

 flowers with only three petals that in those stems examined by 

 myself by far the greatest part of the flowers were three- 

 petaled. 



In my book " Alpenblumen " Dr. Focke of Bremen has 

 detected two errors of naming, which immediately ought to be 

 corrected : the flower described and illustrated on p. 171 is not 

 Empetium nigrum, but Azalea procumhcns, like that of p. 377 ; 

 Ceriiitlw, in pp. 264, 265, is not major, L., but glabra. Mill = 

 alpina. Kit. Hermann Muller 



Lippstadt 



Geological Climates 

 I HAVE read with much interest and attention the letters 

 that have appeared in recent numbers of Nature on the 

 subject of "geological climates," and although it must appear 

 presumptuous on my part to do so, I shall endeavour to show 

 that each of the distinguished writers of these letters may be 

 somew hat in error on at least one point, which — if I am right — 

 mu^t materially affect the correctness of the conclusions they 

 have come to. 



I think that Mr. Wallace, whilst very justly giving the Gulf 

 Stream and other currents which might exist were certain lands 

 submerged, credit for great influence in ameliorating the rigour 

 of climate, does not fake into sufficient consideration the fact 

 that the waters of the Gulf Stream, although warmer, are, in 

 consequence of holding much more salt in solution, heavier than 

 the colder and less saline Arctic current. 



Some experiments show, as clearly as anything done on a very 

 small scale can, that two waters brought as nearly as possible to 

 the conditions of the Gulf Stream and the Arctic current do-not 

 mingle when simultaneously poured into a long narrow gla-s 

 trough ; the Arctic water invariably taking its place on the 

 surface. 



Supposing then that these two currents meet somewhere about 

 latitude So° or 81° N., the Arctic water flowing south — if my 

 experiments are of any value — will retain its position on the 

 surface and the warm current pass underneath, and thus lose all 

 its heating influence on the air over a Polar area about 1000 

 geographical miles or more in diameter. 



We can have no stronger example of this effect of difference 

 of density of ocean water than is shown by the two currents in 

 and out of the Mediterranean Sea. 



In Nature, vol. xxiii. p. 242, Prof. Haughton says, " The 

 thickness of this ideal ice-cap at the Pole is unknown, but from 

 what we know of the Palaaocrystic ice of Banks Land and Grin- 

 nel Land must be measured by hundreds of feet, and its mean 

 temperature must be at least 20° F. below the freezing-point of 

 water." 



With regard to both the above assumptions — which are in 

 italics — I must beg to disagree entirely with the learned Professor. 

 He appears to consider the so-called Pateocrystic ice as the 

 normal state of the ice atand near the Pole, and as a natural grow th 

 by the gradual freezings or increase of a single floe during a 

 series of years ; whereas I am of opinion that this mis-called 

 Paljeocrys'ic ice is the result of a number of floes being forced 

 over and under each other by immense pressure caused by gales 

 of wind and currents. 



The vvestern and northern shores of Banks and Grinnel Lands 

 are peculiarly well suited for the formation of such ice-heaps, as 

 they are exposed to the full force of the prevailing north and 

 north-west storms, which pile up the ice in a wonderful manner 

 on these shores and others similarly placed, for a distance of 

 miles seaward. The whole of the west shore of Melvile 

 Peninsula is so lined with rough ice of this kind that sledging is 

 impossible. 



It \\iU wholly depend upon the form of land— if any — at 

 or near the Pole, whether or not any floebergs are there. If 

 there is no land it is probable there will be few or none, as 

 the ice will meet with no great obstruction, as it is driven by 

 winds and currents. 



I have no authorities by me that give the thickness of ice 

 formed in one season at or near the winter quarters of any of 

 the Arctic expeditions, except my own in 1S53-4 at Repulse Bay, 

 latitude 66° 32' north. 



The measurements of the ice— taken at some distance out in the 

 bay where there was very little snow— and the mean temperature 

 of the air are given on next page. 



