126 



jVA rURE 



[June 6, 1901 



LETTERS TO THE EDITOR. 

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

 pressed by /lis eorrespondenls. Neither can lie undertake 

 to return^ or t^ coj respond with the luritcrs of reje* ei 

 manuscripts intended for this or any other part of Natuke. 

 No notice is taken of anonvmous communieations.'i 



Vitrified Quartz. 



I THINK Dr. Joly has misunderstood the abstract of my lec- 

 ture. It is impossible not to feel confident that a transparent 

 solid which has a very low coefficient of expansion, which 

 expands very regularly up to 1000° C. and returns very exactly 

 to its original volume when it is re-cooled, which remains un- 

 fused at 1500°, and which bears great and sudden changes of 

 temperature with impunity, must, in the absence of any 

 other really satisfactory material, prove very useful in its appli- 

 cations in thermometry. 



The fact that " quartz fibres " are spoilt when they are re- 

 heated was well known before Dr. Joly read his paper on the 

 subject. I believe it was first observed by Mr. Boys, and it is 

 more than once referred to by Mr. Threlfall in "Laboratory 

 Arts" (see pp. 116 and 119) ; but I do not find that vitreous 

 silica in larger masses is equally sensitive, provided that it is 

 protected, when hot, from the action of basic oxides ; in contact 

 with these it quickly becomes rotten when heated. This last 

 fact suggests an explanation of the defect observed in the fibres. 

 ''Quartz fibres" are spun from vitreous silica in the plastic 

 state when it is in contact with air which teems with dusty par- 

 ticles the dimensions of which are by no means negligible in com- 

 parison with those of the very attenuated fibres. Therefore it 

 seems not unlikely that the fibres consist of less pure silica 

 than larger masses of the material. 



Those who work in silica should take care to use Brazil 

 crystal as free as possible from alkali, for its melting point and 

 other qualities may be expected to depend largely on its purity, 

 and rock crystal from all sources is not equally pure. 



Clifton, Bristol. W. A. Shenstone. 



A Raid upon Wild Flowers. 



I.N the last number of N.M'URE (p. 118) you quote with ap- 

 proval the field studies in natural history, of which the 

 Essex Technical Instruction Committee has issued a programme. 

 I will ask space to state the grounds which lead me to regard 

 this programme as an injury both to natural history and to 

 education. 



The teachers of Essex are invited to make a systematic raid 

 upon our wild flowers, and especially upon such as are tending 

 to extinction. They are to collect, name and dry, not only single 

 specimens, but duplicates for " special fascicles." Local guides 

 are to direct them to the last retreats of the rare plants of the 

 New Forest. Nothing is more to be desired, in my opinion, 

 than that the party may fail to discover the things which they 

 most covet. 



This eradicating scheme is utterly useless for scientific and 

 educational purposes. There is no science in all this drying and 

 naming. It is enough to condemn the programme as an educa- 

 tional project that novices, knowing little or nothing of field- 

 botany, are set to study the subspecies of brambles ! Two pages 

 (14, 15) contain promising headings, but if the work is to be 

 carried out in the spirit of the rest of the programme, this too 

 will end in nothing better than schedules and fascicles and 

 names. 



I should be delighted to learn that the Essex Technical In- 

 struction Committee had abandoned the whole scheme as 

 destructive and educationally barren. L. C. Miall. 



P.S. — I have just been assured (June 4) that only advanced 

 students will be allowed to see the rare plants of the New 

 Forest ; it is not stated whether they will be allowed to gather 

 them. There was no such restriction in the printed programme. 

 My other objections remain. — L. C. M. 



The programme criticised by Prof. Miall is unofficial so far 

 as the Essex Technical Instruction Committee is concerned. It 

 was not considered by the Committee or by any sub-committee 

 before publication. It is needless to say that, although I am 

 myself a member (co-opted) of the Committee, I am thoroughly 

 in accord with the general spirit of the above criticisms. On 

 carefully considering the programme in detail I am, however, 

 bound to point out that there are several misconceptions in Prof. 



NO. 1649, VOL. 64] 



Miall's letter. The programme was drawn up by the Staff 

 Instructor in Biology, Mr. David Houston, and he is alone 

 responsible for its contents. He will, I am sure, be able to give 

 a satisfactory explanation concerning many of the charges 

 brought against his scheme. My only object in availing myself 

 of the courtesy of the Editor is to remove the impression that 

 the programme is officially authorised by our Committee. 



R. Meldola. 



The Reported Earthquakes in the Channel Islands 

 and South Devon on April 24. 



In a recent letter to N.ATL'RE, the Hon. RoUo Russell refers 

 to some supposed earthquakes felt along the coasts of the Eng- 

 lish Channel on April 24. As accounts of them have also 

 appeared in several London and provincial papers, it may be 

 worth while to state briefly the results of my inquiries. 



The disturbances bear a strong resemblance to those caused 

 by the firing of distant heavy guns. Between about i and 

 1.45 p.m. five shocks were felt in Guernsey, and eight at Paign- 

 ton in South Devon. They were of very short duration ; win- 

 dows were shaken, but there was no perceptible tremor of the 

 ground. Observers in Guernsey compared the sounds to thunder- 

 or the firing of very heavy guns ; but those on the English coast 

 seem to have been generally unconscious of any sound. Vet the 

 impression of an observer at Salcombe was that a cannon had 

 been fired to the south, but " too far away to bring the noise." 



Trials with heavy guns are said to have been made along the 

 coast of France on April 24. I have not succeeded in ascertain- 

 ing the place or time of the firing ; but that the report assigns a 

 possible cause of the supposed earthquakes will, I think, be 

 evident from the above account. Charles Davison. 



Birmingham, May 29. 



Foreign Oysters acquiring Characters of Natives. 



May I call attention to some curious facts with regard to 

 oyster culture? I do not know whether the evolution they 

 undergo is brought about by Lamarckian factors, or whether it 

 is brought about by natural selection, but no doubt a correct 

 interpretation could be given by some of your readers. 



The facts are as follows : — Oysters of the species Ostrea 

 edtilis, one year old, are brought from Brittany, in France, and 

 transplanted at Hayling Island. After two years on the Hayling 

 beds they are transferred to Whitstable. While they are at 

 Hayling they acquire the characteristics of flavour, and texture 

 and colour of shell of the oysters native to Hayling, yet they 

 are distinguishable as originally from Brittany. When they are 

 transferred to Whitstable they acquire the characteristics of 

 Whitstable, yet they are distinguishable as originally from Hay- 

 ling and Brittany, and are quite distinct from oysters native to 

 Whitstable. Sometimes they have been brought direct from 

 Brittany and laid at Whitstable for three or four years, and, 

 although all the new growth they acquire is characteristic of 

 Whitstable, yet they are distinct from Whitstable natives, and 

 can be easily detected by experts. 



Now the curious point is this : these oysters are known to 

 spawn at Whitstable, yet oysters " spat" from this spawn have 

 never been found. There are found, however, especially the 

 last few years, immense quantities of oysters which resemble the 

 ancient native oysters of Whitstable, and are declared by experts 

 to be Whitstable natives, yet differing from them slightly in 

 coarseness of shell and greater growing power, and in being 

 more susceptible to cold weather than the ancient Whitstable 

 natives. Amongst oyster experts these oysters are considered 

 to be the offspring of the oysters originally brought from 

 Brittany, and this opinion is supported by the fact that when 

 these oysters spawn at Hayling the spat from them resemble in 

 every way the oysters native to Hayling. Can the oysters that 

 become changed in this way be considered to have acquired 

 their new characteristics by Lamarckism or by natural selection ? 



London, May 22. J. M. Tabor. 



The Cape Viper. 



To-day the Cape viper (Causiis rhoiiibcatus) laid several eggs. 

 The keeper says this has happened before. As Causus is one of 

 the Viperids, and as the Viperid.-e (except Atractaspis) are, as 

 their name implies, viviparous, or, to be accurate, ovo-viviparous, 

 it would be interesting to know whether this is a freak, or 

 whether the Causidje are oviparous in their native state. 



Claude E. Benson. 



5 Elvaston Place, Queen's Gate, S.W., May 15. 



