Jan. 20, iSSi] 



NATURE 



267 



the freezing-point ; and if we tal<e the area of the water as 

 about equal to that of the land, we shall have heat enovigh to 

 raise the whole Arctic ocean to a depth of full iSo feet more 

 than 20° F., or to a mean temperature of 52° F., and as this 

 would imply a still higher surface temperature it is considerably 

 more than I require. 



Unless therefore Prof. Haughtnn can prove that the amount 

 of ice now forming annually in the Polar regions is very much 

 more than an average of five feet thick over the whole area, his 

 own figures demonstrate my case for me, since they prove that the 

 rearrangement of land and sea which I have sugge^t<;d would 

 produce a permanent mild climate within tlie Arctic circle and 

 proportionally raise the mean temperature of all north-temperate 

 lands. 



Briefly to summarise my present argument : — Prof. Haughton's 

 fundamental error consists in assuming that the true way of 

 estimating the amount of heat required in order to raise the 

 temperature of the Polar area a certain number of degrees is, — 

 first, to suppose an accumulation of ice indefinitely ^rcnfrr than 

 actually exists, and then to demand heat enough to melt this 

 accumulation anmmlly. The utmost posiihlc accumulations of 

 ice in the Arctic area, during an indefinite number of years, and 

 under the most advene phydcal conditions imaghiable, are to be 

 all melted in !?«<?_)'£»;-; and the heat required to do this is said 

 to be the "accurate measure" of that required to raise the 

 temperature of the same area about 20°, at a time when there 

 were no such great accumulations of ice and when all ihe physi- 

 cal conditions adverse to its accumulation and favourable to its 

 dispersal were immensely more powerful than at present ! 



When this func'amental error is corrected, it "ill be seen that 

 Prof. Haughton's calculations are not only quite compatible 

 with my views, but actually lend them a strong support. 



Alfred R. Wallace 



By the courtesy of Mr. Ingram I am enabled to say that the 

 tree at Belvoir supposed to be Arauciiria Cunninghami is in 

 reality, as surmised by Capt. King, Cunninghamia sinensis. 

 The Cunninghamia is a native of Southern China, whence it 

 has been introduced into Japan. In this country it was origin- 

 ally grown under glass, but, as the instance at Belvoir illustrates, 

 such protection is not absolutely requisite. The tree is however 

 somewhat tender, and so far as I know has never produced its 

 cones in this country in the open air. 



As to the Bamboos hardy in this country, it may be w ell to 

 warn those who are not familiar with the plants not to expect to 

 see the gigantic and rapidly-growing grasses that go under this 

 name in the tropics. Rarely indeed do they attain in this country 

 the dimensions even of the Arundo dona.x, so familiar to travellers 

 in Italy. As accuracy of nomenclature i-; proved in this and the 

 foregoing instance to be a matter of much moment, it may be 

 well to say on the authority of the late General Munro that the 

 Himalayan plant commonly grown in gardens as Arundinaria 

 falcata is more correctly called Thamnocalamus Falconeri, that 

 the Bambusa gracilis of gardens is the true Arundinaria falcata 

 of the Himalayas, and that the Japanese Bambusa metake is 

 Arundinaria japonica. General ^Iunro's monograph of this 

 group is to be found in the twenty-sixth volume of the Transac- 

 tions of the Linnean Society, part I, 186S, w'hile his remarks 

 on the cultivated species may be found in recent volumes of the 

 Gardeners^ Chronicle, particularly in vol. vi. 1876, p. 773. 



The simultaneous flowering of Thamnocalamus Falconeri 3. few 

 years ago in all parts of Europe created much attention, and was 

 indeed a remarkable illustration of hereditary tendency mani- 

 fested under very varied climatal conditions. The flowering 

 of this grass was by no means looked on with unmixed gratifica- 

 tion, as it entailed as a consequence the death or protracted 

 enfeeblement of the plant. 



A visit to Kew or to any of our larger nurseries will suffice 

 to show that there are other Bamboos (that is, grasses belonging 

 to the group Baiubusea:, if not true Bambusas) which are hardy 

 enough to withstand even such rigorous winters as those of 

 1878-9 and 1879-80. Maxwell T. Masters 



Climate of Vancouver Island 

 The letters on this subject which have appeared in Nature 

 (vol. xxiii. pp. 147, 169), have reminded me of a "Prize Essay 

 on Vancouver Island. By Charles Forbes, Esq , M.D., 

 M.R.C.S.Eng. , Surgeon Royal Navy," which was publi hed by 

 the Colonial Government in 1862. It consists of sixty-one 



closely-printed octavo pages and eighteen pages of Appendix ; 

 the latter containing several Tables on the Meteorology of the 

 Colony. 



The following is a portion of the "Abstract of Meteorological 

 Observations, taken at the Royal Engineer Camp, New West- 

 minster, during the year 1S61, by order of Cok R. C. Moody, 

 R.E., Commanding the Troops. Lat. 49° 12' 47' N., Long. 

 122° 53' 19" W." (p. 3, Appendix) : — 



Max. temp, of air in shade at 9.30 a.m., July g, 74'3' F. 



>' !> i> 3.30 p.m. ,, 84"o ,, 



Mean ,, ,, 9,30 a.m. 48"8 ,, 



i> ,, ,, 3.30 p.m. 52'2 ,, 



Min. ,, ,, 9.30 a.m., Jan. 21, 20-0 ,, 



... >. ,, 3.30 p.m., Dec. 23, 24-0 ,, 



Min. temp, on grass on January 21 lo'o ,, 



All the observations were made at 9.30 a.m. and 3.30 p.m. 

 daily throughout the year. Wm. Pengelly 



Torquay, January 6 



Dimorphic Leaves of Conifers 

 It is now generally believed that some of the varying forms 

 assumed by individual plants or animals in the coarse of their de- 

 velopment are as it w ere the reflex of an ancestral state of things. 

 From this point of view the different forms of leaves assumed by 

 some Araucarias, as well as by many other conifers, become of 

 particular importance. The Retinosporas now so common in 

 our gardens and on our balconies represent an immature stage ot 

 some Thuya, the proof of which statement is occasionally fuiTiished 

 by the plants v, hich suddenly assume the foliage characteristic of 

 that genus. In various species of juniper, notably in the Chinese 

 juniper, two forms of leaf representing the juvenile and the adult 

 condition occur together on the same branch. 



Assuming that the juvenile, or "larval " forms, as they have 

 been called, do really represent previous conditions in the history 

 of the species, it might be expected that some of the fossil coni- 

 ferse would be characterised by the possession of this larval 

 foliage to the exclusion of any other. But if I mistake not both 

 forms of foliage have been met with in fossil as in recent conifers, 

 and the pedigree of these plants is by so much the more pushed 

 back. 



The resemblance in the form and arrangement of the adult 

 leaves in some Thuyas and allied plants to the disposition of the 

 leaves in Selaginella should not be overlooked in this connection 

 nor the clo'e resemblance between the foliage of some species of 

 Lycopodiuni proper and the " larval "' leaves of many conifers 

 as above referred to. Maxwell T. Masters 



Dust and Fogs 



The meteorological conclusions of Mr. Aitken's important 

 paper, published in Nature, vol, xxiii. p. 195, will, if adopted 

 without further examination, even temporarily, exercise an un- 

 fortunate influence upon the present attempts to rid the atmo- 

 sphere of our large towns of their ever-recurring fogs, glooms, 

 and mists, and those conclusions certainly are not supported by 

 such evidence as we already have as to the production of fogs on 

 a great scale, however much indicated by experiments in the 

 laboratory. It is stated that, " It having been also shown that 

 all forms of combustion, perfect and imperfect, are producers of 

 fog nuclei, it is concluded that it is hopeless to expect that, 

 adopting more perfect forms of combustion than those at present 

 in use, we shall thereby diminish the frequency, persistency, or 

 density of our town fogs." Now, first as to frequency : what are 

 the facts with regard to localities difi^ering in their methods or 

 materials for producing heat ? Every one living in or near 

 London knows that fogs, thick mists, and dark days are far more 

 frequent within than without its circumference, and experi- 

 ment has shown that sunshine is both less frequent and much 

 less intense within the metropolis. And, according to Mr. 

 Aitken's theory, something of the same 1- ind oufiht to be observed 

 wherever large quantities of fuel are burned, whether smokeless 

 or not. Thus, the large towns of the Continent, where wood 

 and charcoal are in general use, would have their peculiar urban 

 fog--. But they are free from any fogs beyond those which are 

 common to the country. And Paris, before coal was much used, 

 ought to have been distinguished by more frequent fogs than the 

 surrounding country. But it was not so marked out. No oasis 

 of fog prevailed there when the sun shone brightly beyond its 

 precincts, as in our own capital. And Philadelphia, which burns 



