April 13. 1893] 



NATURE 



563 



occasionally until March 18. They seem to have been most 

 intense on March 12. Mr. Elliott says with regard to the 

 shocks on that day : — " The shocks between 7. 10 p.m. and 7.20 

 p.m. were very sharp, and followed one another rapidly. The 

 sharp succession of shocks at 3. 10 a.m. on the 13th inst. very 

 much resembled this batch. The loud roar that accompanied 

 each shock was very noticeable, and we could hear it distinctly 

 immediately before each shock, in fact, could hear the earth- 

 quake coming along the hills to us. None of the shocks had 

 that long undulatory motion that is usually felt when we have 

 an earthquake that is felt throughout the islands, but the feeling 

 was that we were being heaved up and twisted round, and the 

 bumps seemed to give us a push northwards, and I could not 

 help imagining that we were being pushed up to Guadaloupe. 

 I mention this as showing how marked was the direction of the 

 shocks. After 3.10 a.m. on the 13th the shocks became so 

 frequent that I stopped noting them down, until after a short 

 lull a sharp one was felt at 9.15 a.m." 



The weather has continued very fine over the British Islands 

 during the past week, scarcely any rain having fallen in any 

 part. With a very trifling exception in the south and east, the 

 drought has continued since March 4, and in the south-east of 

 England there has been no rain for upwards of three weeks. 

 The temperature has been somewhat lower generally in the day- 

 lime, although in the inland and southern portions of the King- 

 dom the maxima during several days varied between 60° and 70°, 

 but at the eastern coast stations the maximum temperature on 

 several days did not exceed 45°, owing to the sun's rays being 

 obscured by cloud and fog. During the latter part of the period 

 the barometer fell slowly but uniformly ; in the north of our 

 islands the weather became less settled, and on Tuesday snow 

 was falling in the Shetlands, still the general conditions indicated 

 a probable continuance of dry weather, and an anticyclone in the 

 north was spreading southwards. The Weekly Weather Report 

 of the 8th instant showed that the percentage of bright sunshine 

 for that period ranged from 38' to 60° in Scotland, from 53" to 

 66^ in Ireland, and from 61° to 74° in England, while in the 

 Channel Islands it was as high as 79°. 



A SUMMER excursion to the Giant's Cause way for scientific 

 study is being organised by Mr, C. Carus-Wilson. It is pro- 

 posed that the party shall start for Portrush on July I or earlier, 

 and return, if possible, through Dublin, so that they may have 

 an opportunity of meeting the members of the Geologists' Asso- 

 ciation, who are this year to visit the Wicklow Mountains. 



We have received a copy of a new prospectus of the electrical 

 and general engineering college and school of science, Peny- 

 wern House, of which Mr. G. W. de Tunzelmann is principal. 

 It gives an account of recent extensions, and of others which 

 are in progress. 



In the " Annals of Natural History" for the present month 

 will be found an account of a very interesting zoological novelty. 

 Mr. R. T. Giinther describes and figures a remarkable new 

 form oi Medusa, or jelly-fish, that occurs in Lake Tanganyika. 

 Until recent years, when the little Limnocodiuin was found 

 l.ving in the Victoria Lily-tank of the Botanic Gardens, 

 Regent's Park, it was believed that the Medusa were nearly 

 exclusively oceanic. It is now shown that the freshwater lake 

 Tanganyika is the home of a peculiar member of this group. 

 The existence of such an organism in Tanganyika was asserted 

 some years ago by the German naturalist. Dr. Boehm, and 

 Prof, v. Martens, of Berlin, even went so far as to name it 

 Tanganjiae, although he had never seen a specimen. Mr. 

 Giiniher now supplies us with a full description of this 

 singular Hydrozoon, which he refers to a new genus, 

 Limnocnida, adopting the suggestion of v. Martens as to its 

 specific name. Limnocnida tanganjica is, as might have been 

 NO. 1224, VOL. 47] 



anticipated, perfectly different from all the members of the 

 group hitherto known, and probably represents a distinct 

 family, but its exact position cannot be settled positively until 

 the mode of its development has been ascertained. 



A r.ooD descriptive article on the prehistoric remains at 

 Abury is contributed by Mr. A. L. Lewis to Science of March 

 24. The editor appends a note in v/hich he says it has been 

 thought that many Americans who, when in England, visit 

 Stonehenge, may not be aware how many remains of a similar 

 character, which they might also wish to inspect, exist in the 

 British Isles. He has accordingly made arrangements for a 

 series of short articles which shall give a description of each ot 

 the principal circles, and state what points should be noted and 

 how it may be most easily visited. 



Mr. H. L. Jo.nes records, in the Botanical Gazette, an ex- 

 ample of a graft-hybrid between two different varieties of gera- 

 nium, a red and a white. In several successive years the flowers 

 partook of the characters of both parents ; some were pure red, 

 and others pure white ; others had some of the petals white, others 

 red ; while in others again the petals were red mottled with 

 white, or white mottled with red. 



If we may judge from the tone of an article on "conditions 

 of forestry as a business," contributed by Dr. W. J. Beal to the 

 New York Engineering Magazine, a good deal of anxiety is felt 

 by some Americans about the extraordinary rapidity with which 

 trees are vanishing from their country. Michigan had at one 

 time a supply of standing pine which was believed to be well- 

 nigh inexhaustible. Now it U found only in " small tracts in 

 the back counties." The fathers and grandfathers of the present 

 generation of Americans "cut down and burned the finest of 

 the trees to make room for crops and pasture." " We have been 

 taught, " says Dr. Beal, "to destroy trees, not to save them — 

 much less to replant." The growth of interest in forestry will, 

 he thinks, be slow for some time yet, but he anticipates that 

 popular feeling about the matter will be greatly changed, and 

 that salutary laws will be passed, before the close of the present 

 century. 



Mr. L. J, Tremayne notes, in the current number of the 

 Entomologist, that he was walking down the Thames Embank- 

 ment about two o'clock on March 8 (the sun being just at the 

 time rather powerful), when a specimen of Vanessa polychloros 

 alighted on the pavement about a couple of yards from him. 

 The insect was, he thinks, perfect, and appeared very fresh. 

 He tried to catch it, but it flew into the gardens on his left, and 

 he saw no more of it. There was, however, no mistaking the 

 specimen, which expanded its wings right in front of Mr. Tre- 

 mayne. This occurred just above Waterloo Bridge. 



At the Technical Institute of St. Petersburg, M. Vladimiroft 

 has deduced from experiment a set of rules for estimating the 

 quality of vulcanised caoutchouc {Rev. Sci.). Recourse is had 

 to physical properties, chemical analysis not giving any sure re- 

 sult. The following, in brief, are the conclusions : — (i) Caout- 

 chouc should not give the least sign of cracking when bent to an 

 angle of 180°, after 5 hours' exposure in an air-bath at 125° C. 

 (the specimens 2*4 in. thick).. (2) Caoutchouc having not more 

 than half its weight of metallic oxides should bear stretching 5 

 times its length before rupture. (3) Caoutchouc exempt from 

 all foreign matter except sulphur should be capable of stretch- 

 ing at least 7 times its length before rupture. (4) The extension 

 measured just after rupture should not exceed 12 percent. o( 

 the original length (with given dimensions). (5) Suppleness 

 may be determined by calculating the percentage of ash after 

 incineration. This may form the basis of choice for certain 

 uses. (6) Vulcanised caoutchouc should not harden in cold. 

 These rules are adopted for the Russian Navy. 



