533 



NATURE 



[April Z, 1880 



Anchor-Ice 



On looking over some old papers I find a few notes on a 

 lather curious instance of the mode of formation of anchor-ice 

 v hich was accidentally brought to my notice. 



When at Repulse Bay on the Arctic Circle many years ago, I 

 went out one morning in the latter part of September to shoot 

 deer, and on my way forded a stream of no great size, dry shod, 

 having on Eskimo w aterproof boots, the water being little more 

 than a foot deep. The parts of this small river which had a 

 slow current were already covered with ice, but not strong 

 enough to bear my weight. For so early a date the day became 

 extremely cold, and on my way home, after an absence of about 

 eight hours, I was surprised to find, when recrossing the stream, 

 that the water came high over my knees, filling my boots. 



On examination I discovered that this rise of water was pro- 

 duced by an accumulation of frozen water fully eight or nine 

 inches deep, adhering to the stones at the bottom of the rapid, 

 all of which must have been formed, since the morning, at the 

 rate of not less than one inch in the hour. The foot sank readily 

 into this "slushy" formation, a lump of which rose buoyantly 

 to the surface at each step. 



Unfortunately I could not wait to study the process of con- 

 struction as it was getting "dusk," and my wet clothes — which 

 had to be cut off when I got to my tireless tent — began speedily 

 to freeze. 



I have seen "anchor-ice" in rivers many times, and believe 

 that two or three conditions are requisite for its formation, 

 namely : — 



1. A rocky or stony bottom. 



2. Shallow water as compared with that higher up the stream. 



3. A swifter current and rougher water in comparison with a 

 smooth and slower motion immediately above. 



All these conditions existed in the present case. 



The ford was a rapid, and as I have already mentioned, shallow, 

 whilst immediately above there was a pool of nearly still water, 

 three or four times as deep, which was ice-covered to within a 

 few yards of the ford. On the surface of this almost still water, 

 close to the rapid, where it was yet unfrozen, numerous small 

 Crystals of ice were forming and floating, indicating that the 

 water was at — perhaps colder than — the freezing point. 



^ hen these ice-crystals and surface cold water get into the 

 turmoil of the rapid, they are brought into contact with the rocks 

 and stones at the bottom, which are thus cooled down to the 

 freezing point, and become convenient nuclei for ice-formation. 1 



Supposed anchor-ice is often found at the bottoms of shallow 

 lakes and ponds, and also in the quieter pools of rivers ; but this, 

 as far as my experience goes, is not true anchor-ice, but is formed 

 in the usual manner, beginning at the surface and increasing in 

 thickness downwards until it reaches the bottom, to which it 

 freezes firmly and remains attached during the spring and early 

 part of summer— perhaps longer — with two, three, or more feet 

 depth of water over it, as it slowly thaws. 



The manner in which anchor-ice is formed may be well known ; 

 if so, the fact that no satisfactory description of the process has 

 come under my notice is the only apology I have to offer for 

 troubling you with this communication. J. Rae 



4, Addison Gardens, Kensington, W., March 25 



Diatoms in the London Clay 

 I regret to find that there are some beautifully mounted 

 slides in circulation in London that have been sold, and are 

 labelled as diatoms from the London clay, which are not what 

 they purport to be. To prevent further disappointment to 

 microscopists, will you allow me to say that arrangements have 

 been made for slides of the London clay diatoms to be procurable 

 shortly at any of the usual places ? Due notice will be given by 

 advertisement in this paper, when and by whom slides can be 

 supplied to the trade. W. H. Shrubsole 



Sheerness-on-Sea 



Carnivorous Wasps 



In Nature, vol. xxi. p. 417, there is the statement that 

 common wasps are carnivorous. I can prove this fact also by 

 my own experience. I observed, one summer, in a country 



1 The way in which masses of ice. yards in extent, which have been floating 

 on the surface in the smoother ana slower current of a river, disappear when 

 they enter a rapid and remain under water f r some time, may be noticed in 

 any country where the winters are cold enough, at the breaking up of rivers 

 m the spring. 



house, where wasps were shut in a room, that from lack of their 

 usual food, and probably forced by hunger, they caught flies and 

 devoured them. I saw several times wasps with a fly between 

 their mandibles creeping on the window-glass, or eating them. 

 Generally the wings and the head of the flies were mangled. I 

 was one day so happy as to see a wssp catch a fly on the window, 

 and observed how cleanly it picked the wings of the fly in order 

 to hinder its flying away, and after having done so, how the 

 wasp ate the head. I saw also some wasps quite prostrate and 

 dying of hunger at last. I think that this fact could easily be 

 verified by experiments. Lewis Bod 



Hungary, Stuhlweissenburg, March 20 



TWO ENTOMOLOGISTS 

 THE brief notices that appeared in the Times and in 

 -*- our last number of the death of two of the most 

 prominent Continental entomologists, were scarcely suffi- 

 cient, and we therefore give a slightly more extended 

 account of the lives and labours of both. 



Ernest August Helmuth von Kiesenwetter, born in 

 1S20, was a member of the Saxon Privy Council, and was 

 highly esteemed in his native country. Although only 

 sixty years old at the time of his death, his_first recorded 

 published paper dates so long back as 1842. He was one 

 of the most accomplished and conscientious German 

 entomologists, and one of the hardest workers — a con-. 

 siderable traveller, so far as entomological journeys in 

 different parts of Europe are concerned, a close observer, 

 and a man above suspicion as to the nature of his work. 

 Though chiefly a coleopterist, he attended more or less to 

 all orders of insects, but limited his studies principally to 

 the European fauna. The greater part of his memoirs 

 appeared in the Slettincr entomologische\Zcitung and the 

 Berliner entomolo^ische Zcitschrift, and the list is very 

 long. But his principal work is undoubtedly concentrated 

 in the part he took in the " Naturgeschichte der Insecten 

 Deutschlands," commenced by Erichson, and completed 

 so far as the greater portion of the Coleoptera are con- 

 cerned. How far Kiesenwetter's decease may render 

 even this portion incomplete, and prevent the realisation 

 of the original scheme, we know not. It was a grand 

 idea with an unfortunate title. Few works on systematic 

 entomology have rendered so much service to workers 

 occupied on those groups already attended to, and it will 

 remain a monument to the industry of all concerned. 

 Its title has brought upon it the reproach of being a 

 natural history in which there is no natural history, 

 a severe criticism which a little forethought on the 

 part of the originator should have avoided. Kiesen- 

 wetter had to assist in carrying out a set programme. 

 He did his part of it well and faithfully, and his other 

 writings prove that the biological side of the question was 

 always prominently before him. 



In S. C. Snellen van Vollenhoven Holland has lost its 

 Westwood. He was born in Rotterdam on October 18, 

 1S16, and not even his intimate correspondents here knew 

 of anything likely to cut short the career of so prominent 

 a man. Attached for many years to the Natural History 

 Museum at Leyden as Director, he retired from that 

 position a year or two ago, and so much was he respected 

 that a medal was struck in his honour upon that occasion. 

 Van Vollenhoven was a naturalist in the fullest sense of 

 the term. It has been said of him that his principal work 

 was his " Faune entomologique des Indes Orientales," 

 meaning thereby (principally) of the Dutch Indies. This 

 work was sufficient to base a reputation upon, but it was, 

 from a biological point of view, not the most important. 

 He occupied himself especially with the insects of 

 Holland, and it is for the works he produced upon them 

 that his memory will be everlastingly respected by Dutch- 

 men, and by all other entomologists who think there is 

 yet much to be done in working out the fauna of Europe. 

 Indeed we fancy the exotic work was forced upon him by 

 the necessity of his position, rather than done con mnorc. 





