294 



NATURE 



\jfan. 24, 1 8^9 



vance has been made in this year's volume, both as 

 regards size and the number of articles included ; the 

 pages of the calendar which were formerly devoted to 

 the dates of meetings of Societies have here been left 

 blank for the sake of persons desiring to make notes 

 or memoranda. 



Valuable hints on all topics are given both to amateurs 

 and professionals, no single department of the work, as 

 far as we can find, having been neglected. 



A brief summary of the year's work is given by e 

 editor, touchin^j upon the gradual merging of the brown 

 and purple tones into those of darker and more engraving- 

 like type, the advancement made in flash-light photo- 

 graphy, and the new method of platinum-printing. 

 The summary conclud-3s with an obituary of those who 

 have passed away since the last issue. 



Next follow series of articles, commencing with one on 

 " Iron Printing," by the editor, and continuing with those 

 contributed by Abney, Burton, Perry, Piazzi-Smyth, and 

 many others. 



Twenty pages are devoted to an epitome of j progress 

 during the year 1888, and then are added a list of useful 

 receipts, standard formulae, reference tables, &c. 



The Photographer^ s Diary and Desk-book for 1889. 

 Compiled by the Editor of the Camera. (London: 

 Published at the Office of the Camera, 1889.) 

 Of the various diaries brought out for the present 

 year, that issued by the proprietors of the Camera 

 will be sure to give great satisfaction to photographers, 

 both amateur and professional. This differs from other 

 photographic diaries in two respects : in the first 

 place, it is much larger, there being plenty of room for 

 notes on experiences of various kinds, results of manipu- 

 lating, developing difficulties, and many other details 

 w£ll worth recording, which are often so useful and 

 valuable for reference. In the second place, there is 

 a great amount of useful information condensed in the 

 first fifty pages. Besides various tables and processes 

 of developing, printing, &c., information similar to that 

 included in almanacs and other diaries is inserted ; the 

 tables and standard formulae relating to photography 

 being printed in larger type, to enable the worker, when 

 in the dark room, to refer to them. This diary is a very 

 complete and useful publication, and, as a book of 

 reference, is most handy. 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he under- 

 take to return, or to correspond with the writers of, 

 rejected manuscripts intended for this or any other part 

 of Nature. No notice is taken of anonymous communi- 

 cations. "l 



The Climate of Siberia in the Mammoth Age. 



A SHORT time ago I was discussing with my friend Mr. 

 Henry Seebohm the various problems connected with the dis- 

 tribution and migration of birds in Siberia, about which he has 

 collected so many facts. One fact which he mentioned to me 

 seemed to have a much wider interest than a merely ornitho- 

 logical one, and to illustrate from an unexpected quarter a 

 conclusion which you have allowed me to urge in your columns, 

 and which forms a notable postulate in my recent work on " The 

 Mammoth and the Flood." I mean in reference to the climate of 

 Siberia during the Mammoth age. The views I have advanced 

 on this subject are not my own. I have merely followed in the 

 footsteps of almost every recent Continental authority, especially 

 the authorities with the greatest claims to attention — namely, the 

 Russian naturalists who have visited Northern Siberia. They 

 maintain — and I think the position is unassailable — that during 

 the Mammoth period that district which is now a bare /«W;-a, on 



which neither in summer nor winter could herds of pachyderms- 

 find food or shelter, was marked by a temperate climate, and was 

 probably occupied by forests to the very l)orders of the Arctic 

 Ocean. 



This view, which i.s supported by so many facts, was finally 

 established when it was shown by Schmidt and others that 

 rooted trunks of trees are found in the beds containing Mammotb 

 remains far north of the present range of trees, and that southern 

 forms of fresh-water mollusks, such as the Cyrena fluminalis, 

 are also found preserved in the same beds in Siberia far to the 

 north of any place where they will now live. Ihese facts are 

 consistent only with the former existence of a temperate climate 

 in Siberia. 



It is interesting to meet with support for this position from 

 the present avifauna of the Palsearctic region. Mr. Seebohm,. 

 who has an unrivalled collection of skins, illustrating the 

 ornithology of this region from Britain to Japan, assures me 

 (and, in fact, he showed me the evidence) that certain birds — 

 notably the jay, the nuthatch, the marsh-tit, coal-tit, and long- 

 tailed tit, the great and little spotted woodpecker of England 

 and lapan, and in one case of Northern China — are virtually 

 undistinguishable. Similarly, the hazel grouse of Japan re- 

 sembles that of the Pyrenees, and the nutcracl^er of Japan and 

 China is like that of Western Europe. V\ hile this is so, the 

 forms of these same birds found in the intervening district of 

 Siberia differ very materially, and have, I believe, in almost 

 every case, been treated as specifically distinct. Ttiis is 

 assuredly a very interesting fact. Both Britain and Northern 

 Japan are in the same zoological province — namely, the Pah«- 

 arctic region, over which there is a singular constancy of types 

 and forms, and yet we find that in certain birds the forms at 

 either extremity of the province are closely allied, while the 

 intermediate form differs. This is at one with the fact that the 

 climate of the two extremities is very similar, and that of the 

 intervening district is very much more severe in the winter. We 

 can hardly doubt that the general adherence to a normal type 

 whi;h marks the fauna and flora of the Palrearctic region (and 

 which was even more marked, and amounted, so far as we know, 

 to identity, in the Mammoth period) is due to the fact that 

 formerly, and in every probability in the Mammoth period, an 

 equality of conditions prevailed throughout. This equality has- 

 been maintained at the extremities of the region, with the result 

 of maintaining the old forms and types unaltered ; while it has 

 changed and grbwn more severe in the intervening region, with 

 the corresponding result of altering the types there. The con- 

 servatism of forms at either end of the province proves unmis- 

 takably a conservatism of conditions. This is assuredly a very 

 interesting independent proof, if proof be now needed, that the 

 climate of Siberia was once much more temperate throughout, 

 and like that of Britain and Japan, and this doubtless in the 

 Mammoth age. 



I may add that it seems to me very nearly certain 

 that this change of climate in Siberia was the cause of the con- 

 version of what were once sedentary birds there into birds that 

 migrate to South Africa and elsewhere — a migration which has 

 been very well illustrated by Mr. Seebohm. That the data of 

 the commencement of this migratory tendency is not very remote 

 in time is shown by the fact that the birds have not been more dif- 

 ferentiated, notwithstanding the very various conditions prevail- 

 ing in their several winter-quarters. I believe myself that in 

 the Mammoth period, when the climate of Siberia was tem- 

 perate, there was no need for these tremendous migrations, 

 which were, no doubt, originally induced by the necessity for 

 finding food in winter ; but that most, if not all, of these migra- 

 tory birds were then either stationary in Siberia, or were only 

 local migrants, like so many of our own birds are now. 



Mr. Seebohm, in his recent work on the Charadriidsc, has 

 invoked the Glacial epoch to account for the facts presented by 

 that singularly distributed genus. I know of no Glacial epoch 

 in Siberia before the present. The last epoch there, as we can 

 test and prove by the presence of the undecayed carcasses in the 

 frozen ground, was the period when the Mammoth lived. It 

 was when that period closed (and as I claim to have proved 

 closed very rapidly) that the present Arctic conditions of the 

 Siberian climate were introduced, and I would urge it was from 

 this date that the present laws controlling the migration of 

 Siberian birds arose. 



This seems an inference of some importance ; and when the 

 ornithological history of the eastern half of the Palsearctic region 

 is written in detail, it will very probably be shown that the 



I 



