January g, 19 13] 



NATURE 



513 



any evidence summarised? There is very little in 

 the book showing that any progress has been 

 made in the interpretation of Neolithic monuments, 

 the epithet "sepulchral" being- applied to the 

 archajological dead wall in that direction. The 

 notion that the religion of the monument-builders 

 is to be interpreted by existing savage life seems 

 to be extremely fallacious, where evidence of a 

 high culture is hypothetically reconciled with the 

 lowest savagery (pp. 64, 65). 



There is a body of other evidence of Neolithic 

 culture which in this book is formally ignored, 

 but just in the connection where one would expect 

 a brief summary of that evidence, one finds the 

 strongest expression, and by far the weakest argu- 

 ment, to be found in the book. "Popular belief 

 generally attributes the megaliths to the Druids, 

 but the connection is absolutely unsupported by 

 evidence, and the idea is of recent (eighteenth 

 century) origin " (footnote, p. 99). That there 

 was no connection between the Druids and the 

 megaliths is absolutely unsupported by evidence. 

 The idea is certainly older than the eighteenth 

 century, but it is to be admitted that the best evi- 

 dence in point is as recent as the best on the 

 classification of primeval skulls, in as bewildering 

 an abundance as the latter is scarce, much less 

 problematical, accessible to every archaeologist, 

 and so well appreciated when it can be under- 

 stood that the blank, fruitless negations with 

 which Mrs. Quiggin disposes of the subject 

 materially assist, by demonstrating their own 

 futilit}', in securing for the new evidence a fair 

 examination. John Griffith. 



Katalog der paldarktischen Hemipteren [Hetero- 

 ptera, Homoptera — Aiichenorhyncha und Psyl- 

 loideae). By B. Oshanin. Pp. xvi+187. 

 (Berlin: Friendlander und Sohn.) Price 12 

 marks. 

 This useful list of Palsearctic Hemiptera and 

 Homoptera is practically a fifth edition of Dr. 

 Puton's "Catalogue des Hemipteres de la Faune 

 Palearctique," the fourth edition of which was 

 pu1)lished in 1899. The failing health and subse- 

 quent blindness of the French author prevented 

 him from continuing the study of these insects, 

 .ind M. Oshanin, therefore, has done good ser- 

 vice by bringing the catalogue up to date. He 

 takes a wider view of the Palaearctic region than 

 Puton, including Wallace's Mandchurian sub- 

 region, that is, Japan and the greater part of 

 China. Altogether, 5476 species are enumerated 

 under fifty-five families and 1005 genera, and 

 the classification adopted is that of O. M. 

 Renter. The year of publication of each of the 

 genera and species, with the habitat, is given, as 

 was done bv Puton, and an alphabetical list of 

 the species and varieties is to be found on pp. 

 '3i~i77- The recently published "Verzeichnis 

 der palaearktischen Hemipteren mit besonderer 

 Beriicksichtigung ihrer \'erteilung im russischen 

 Reiche," by the same author, gives a full reference 

 to the works in which the species were described. 



NO. 2254, VOL. go] 



LETTERS TO THE EDITOR. 



IThe Editor does not hold himself responsible for 

 opinions expressed by his correspondents. Neither 

 can he undertake to return, or to correspond ivith 

 the writers of, rejected manuscripts intended for 

 this or any other part of N.ature. No notice is 

 taken of anonymous communications.'] 



The Influence of Icebergs on the Temperature of the 

 Sea. 



In the early 'seventies of last century I took con- 

 siderable interest in oceanic circulation. Dr. Car- 

 penter had previously shown that when the warm 

 water moves from the equator towards the poles it 

 gradually cools and sinks near the poles, and he 

 showed that when this current meets with icebergs 

 they have a cooling effect and produce downward 

 currents; this he illustrated by placing some ice at 

 one end of a tank of sea water, when a downward 

 current was produced under the ice, which flowed 

 away along the bottom of the tank towards the other 

 end, where it rose and flowed back along the surface 

 towards the ice. In 1873 I pointed out that Dr. Car- 

 penter's description of the two currents did not give 

 a full statement of what was taking place; that 

 his surface current was not at the surface, but only 

 near it, and that above it was another formed of a 

 mixture of sea water and the fresh water of the 

 melted ice, which had a lower specific gravity, though 

 colder, than the sea water- This cold water flowed 

 away from the ice over the surface of the warmer 

 water. That the ice-cooled sea water was lighter 

 than the sea water was also shown by dividing the 

 experimental tank into two parts by means of a 

 movable vertical partition. The water in one half was 

 cooled bv means of ice in varying amounts, and on 

 removing the partition thfc cold water always flowed 

 over the hot. 



These are all laboratory experiments, and though 

 they help us to understand something of what is 

 taking place while ice is melting in sea water, yet 

 they are not likely to contain all the conditions exist- 

 ing in nature. For this reason the recent investiga- 

 tions of Prof. Barnes on the rise of temperature near 

 icebergs, found by him by means of his microthermo- 

 graph, are most interesting, though I must admit very 

 puzzling. In his Royal Institution discourse (Nature, 

 June 20, 1912) he gives a diagram of the temperature 

 gradient of the sea water when approaching an ice- 

 berg. In this case, when at a distance of a little 

 more than two miles from the berg, the temperature 

 was rising, and rose o'6 of a degree C. by the time 

 the observing vessel had approached to within a mile 

 of the berg. From this point the temperature began 

 to fall, and at half a mile from the berg it had fallen 

 2-;°. On passing beyond the berg the temperature 

 began to rise, and at a distance of about six miles 

 it had risen about 17°, after which it began to 

 fall. 



In the very interesting and full diagram, showmg 

 the temperatures all round an iceberg, given by Prof. 

 Barnes in Nature of December 12, iqi2, the tempera- 

 ture is shown to be rising on all sides as the berg 

 is approached. Beginning to rise at a distance 

 from it of five miles, it goes on rising right up to the 

 berg, rising from 4-2° to 5-2° C. If these two 

 diagrams represent something typical, why this differ- 

 ence in the two cases? In the first a rise of teni- 

 perature stopping within a mile on one side and six 

 miles on the other, and then a steady fall in tempera- 

 ture on both sides up to within half a mile of the 

 berg, which was as near as it was approached; and 

 in the other rase a steady rise all round right up to 



