June 23, 1892] 



NATURE 



^1Z 



their solutions being near completion. Both at the 

 Universities and elsewhere, the work will still continue 

 to occupy the high position which it has held among 

 treatises of its kind. W. 



The Threshold of Science. By C. R. Alder Wright, 

 F.R.S. Second Edition, Revised and Enlarged. 

 (London: Charles Griffin and Co., 1892.) 

 The primary aim of this book is to interest young readers 

 in various s.mu.e and amusing experiments, illustrating 

 some of the chief physical and chemical properties of 

 surrounding objects, and the effects upon them of light 

 and heat. In the present edition the author has made no 

 change which is likely to interfere with this object, but he 

 has added various scientific appendices, and an excellent 

 chapter on the systematic order in which class experi- 

 ments should be carried out for educational purposes. 

 These additions will be of great service to all who may 

 wish to use the volume not merely as a "play-book," but 

 as an instrument for the training of the mental laculties. 

 Any one who may still have doubts regarding the value 

 of elementary science as an organ of education, will 

 speedily have his doubts dispelled if he takes the trouble 

 to understand the methods recommended by Dr. Alder 

 Wright. The majority of the experiments he has selected 

 must not, of course, be studied merely in his exposition. 

 It is intended that each reader shall make them himself. 

 If that is done, they cannot fail to quicken the intelligence 

 even of " the average boy." 



Key to J. B. Lock's Elementary Dynamics. By G. H. 



Lock, M.A. (London : Macmillan and Co., 1892.) 

 This key will be found most useful both to beginners and 

 teachers alike. The examples are all carefully worked 

 out, many of the more difficult problems being treated at 

 greater length with the view of helping those who are 

 studying without the aid of a teacher. By an intelligent 

 use of this book, a student should acquire a good know- 

 ledge of the method of working out problems as well as 

 the important factor of attacking them in the right way. 



W. 



LETTERS TO THE EDITOR. 



[ The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

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

 manuscripts intended for this or any other part of iiKTVKK. 

 No notice is taken of anonymous communications. ] 



Ice in the South Atlantic. 

 The following account of ice met with in the South 

 Atlantic at the commencement of last April, which has been 

 supplied to the Meteorological Office by Captain Froud, of the 

 Shipmasters' Society, may be of interest to your readers. 

 Robert H. Scott, 

 June 17. Secretary, Meteorological Office. 



Ship Cromdale, London. 



Sir, — I now send you a short account of my unusual encounter 

 with ice in the above ship on our homeward passage from 

 Sydney. 



We left Sydney on March i, and having run our easting down 

 on the parallel of 49° to 50° S., rounded the Horn on March 30 

 without having seen ice, the average temperature of the water 

 being 43° duiing the whole run across. 



At midnight on April i, lat. 56° S., long. 58° 32' W., the 

 temperature fell to 37° 5, this being the lowest for the voyage, 

 but no ice was seen, although there was a suspicious glare to 

 the southward. 



At 4 a.m., April 6, lat. 46° S., long. 36° W., a large 

 berg was reported right ahead, just giving us time to clear it. 

 At 4.30, with the first sign of daybreak, several could be dis- 

 tinctly seen to the windward, the wind being north-west, and 

 the ship steering north east about nine knots. At daylight 

 (5.20) the whole horizon to the windward was a complete mass 



NO. 1182, VOL. 46] 



of bergs of enormous size, w ith an unbroken wall at the back ; 

 there were also many to the leeward. I now called all hands, 

 and after reducing speed to seven knots, sent the hands to their 

 stations and stood on. At 7 a.m. there was a wall extending 

 from a point on the lee bow to about four points on the quarter, 

 and at 7.30 both walls joined ahead. I sent the chief mate 

 aloft with a pair of glasses to find a passage out, but he reported 

 from the topgallant yard that the ice was unbroken ahead. Find- 

 ing myself embayed, and closely beset with innumerable bergs of 

 all shapes and sizes, I decided to tack and try to get out the way 

 I had come into the bay. The cliffs were now truly grand, 

 rising up 300 feet on euher side of us, and as square and true at 

 the edge as if just out of a joiners' shop, with the sea breaking 

 right over the southern cliff and whirhng away in a cloud of 

 spray. Tacked ship at 7.30, finding the utmost difficulty in 

 keeping clear of the huge pieces strewn so thickly in the water, 

 and having in several cases to scrape her along one to get clear 

 of the next. We stood on in this way till 11 a.m., when to my 

 horror the wind started to veer with every squall, till I drew 

 quite close to the southern barrier, having the extreme point a 

 little on my lee bow. I felt sure we must go ashore without a 

 chance of saving ourselves. Just about 11.30 the wind shifted 

 to the south-west wuh a strong squall, so we squared away to 

 the north-west, and came past the same bergs we had seen at 

 daybreak, the largest being about 1000 feet high, anvil-shaped, 

 and at 2 p.m. got on the north-west side of the northern arm 

 of the horse-shoe shaped mass. It then reached from four points 

 on my lee bow to as far as could be seen astern, in one unbroken 

 line. A fact worthy of note was that at least fifty of the bergs in 

 the bay were perfectly black, which was to be accounted for by 

 the temperature of the water being 51", which had turned many 

 over. I also think that had there been even a small outlet at 

 the eastern side of this mass the water between the barriers would 

 not have been so thickly strewn with bergs, as the prevailing 

 westerly gales would have driven them through and separated 

 them. 



1 have frequently seen ice down south, but never anything like 

 even the smaller bergs in this group. I also had precisely the 

 same experience with regard to the temperature of the water in 

 our homeward passage in the ship Derwent three years ago, as 

 we dipped up a bucket of water within half a mile of a huge berg 

 and found no change in the temperature. 



I trust you will warn, as far as possible, those about to sail for 

 the Cape, as these bergs must soon reach that part. 

 I remain, yours truly, 



(Signed) Edgar H. Andrew, Master. 



June 12. 



Land and Freshwater Shells peculiar to the British Isles. 



Mr, Cockerell, in his article in Nature of May 26 (p. 76), 

 draws attention to a list of land and fiesh water shells peculiar 

 to the British Islands in Dr, Wallace's new edition of "Island 

 Life," This work is of such very great importance to every one 

 engaged in the study of the geographical distribution of animals, 

 that It is regrettable the author should have repeated an error 

 made in the first edition. Geomalacus maculosus, as is men- 

 tioned in Mr, Cockerell's article, is not peculiar to the British 

 Islands, A specimen was discovered in Northern Spain as far 

 back as 1868 by Mr. von Heyden, and recorded in the Nach- 

 richtsblatt d. deutschen Malakozool. Gesellschaft by Heyne- 

 mann in 1869. The allied species, supposed to have been found 

 in France, has been proved to be an Arioii ; but several species 

 of the interesting genus Geomalacus have been recently described 

 by Simroth from Portugal, 



Mr. Cockerell also stales that several varieties in the list of 

 peculiar British forms may have to be eventually struck out ; 

 and this is certainly the case, as the variety albolateralis of 

 Arion ater, mentioned as "very distinct," was found near Bre- 

 men, in Germany, and is described in Simroth's "Nalur- 

 geschichte der deutschen Nacktschnecken " {Zcitschr, f wiss. 

 Zoologie, vol. 42, 1885). R. F. Scharff. 



22 Leeson Park, Dublin, June 13. 



THE IMPERIAL INSTITUTE. 



THE Imperial Institute is no longer a castle in the 

 air, an abstraction the meaning of which is to be 

 u essed at through a veil of mist, but a solid and hand- 



