August i8, 192 i] 



NATURE 



779 



had an internal diameter of i6 cm., an external dia- 

 meter of 28 cm., and a height of 6 cm., and it was 

 possible to obtain a magnetic field of many tens of 

 gauss. 



Rising from the copper pipe, the yellowish smokes 

 (obtained with iron electrodes by condensation of iron 

 vapour) showed a thick layer of fumes where traversed 

 by polarised light. In these conditions, putting on 

 the magnetic field, light appears through the crossed 

 Nicols and remains until the field is cut oft". 



In preliminary experiments I was able to deter- 

 mine the following characters of the observed pheno- 

 mena : — 



(i) Turning conveniently the analysing Nicol, 

 chromatic polarisation is obtained. 



(2) With monochromatic light it is not possible to 

 reach extinction by turning the analyser. Using a 

 Babinet compensator, a suitable displacement of 

 fringes, with field excited, was observed, and appeared 

 as positive birefringence. 



(3) With light polarised in a parallel or normal 

 plane to the direction of the field the phenomenon is 

 not manifest. 



Moreover, if the coil is arranged in a vertical posi- 

 tion the phenomena appear if the axis of the coil is 

 normal to the polarised luminous beam, but not if 

 the same axis is parallel to it. 



Tests made with copper electrodes gave quite nega- 

 tive results with the above-described arrangement. 

 This may be explained by the weakness of the field, 

 as by employing a powerful electromagnet the effect 

 appears also with smoke from copper electrodes. 



L. TiERI. 



The Physical Institute, University of Rome, 

 August I. 



The Exploitation of Irish Peat. 



Prof. Ryan in his article under the above title in 

 Nature of August 4 (p. 728) states that the labour 

 difficulty is a serious obstacle in so far that the work is 

 seasonal. I should like to suggest that this can be 

 overcome by adopting the method employed for the 

 production of moss-litter (used for bedding for animals) 

 as now practised in Scotland and elsewhere. This 

 method allows the men employed to be engaged in 

 cutting peat in the earlier part of the winter and 

 whenever the weather does not permit other opera- 

 tions. It follows that a great quantity of the wet 

 peat lies throughout the winter exposed to the 

 weather, and bv the alternate freezing and thawing 

 which it experiences the texture is very much opened 

 up. Consequent on this, when the peat is built up 

 in the spring it dries very much more quickly than 

 material newly cut. 



It is true that this method is not practised bv 

 crofters and others who depend on peat for fuel for 

 domestic consumption, because the resulting product 

 is not the hard, dense, compact body which is most 

 suitable for burning in an open fire. However, for 

 the exploitation of peat on a large scale this should 

 not be necessary, since the peat is bound to be burned 

 in closed furnaces with a strong draught. So far as 

 my experience goes, it leads to the conclusion that the 

 texture only, and not the composition, is altered by 

 exposure during winter. 



The adoption of this method would solve one of the 

 most important labour problems, namely, the con- 

 stant employment of the necessary able-bodied men. 

 It would not permit the employment of women 

 throughout the whole year, but would require their 

 services to be dispensed with for about three months 

 during the worst part of the winter. Whether such 

 an industry could furnish an adequate wage for the 



NO. 2703, VOL. 107] 



workers in it is a question that can be considered only 

 with reference to the specific conditions of surrounding 

 industries and consumers. 



Alexander Fleck. 

 26 Manor House Road, Jesmond, Newcastle- 

 upon-Tyne, August 8. 



Scarcity of Swallows. 



The following may not throw light upon the 

 scarcity of swallows in England this year, as noted 

 in Nature of July 14, p. 628, but will explain a 

 shortage in another part of the world, and may be 

 of interest and suggestive. 



I live in the Gran Chaco of Paraguay, South 

 •America. In July, 1920, there was a succession of 

 dull days extending over a week, accompanied by 

 fine rain and a temperature varying between 20° an^ 

 10° C, strong winds also prevailing. On the 

 fourth day of these conditions the swallows sought 

 refuge in the buildings of the Mission Station, where 

 I reside, and for three days dead bodies of the birds 

 were picked up, and afterwards no more birds were 

 seen. A few days later I had to make a journey 

 which took me in a direct line for 120 miles, during 

 which I did not see a single swallow. Managers of 

 four cattle farms through which I passed reported a 

 mortality of swallows at their establishments similar 

 to that seen at the Mission Station. From other 

 reports I concluded that the whole area of the Gran 

 Chaco had been affected by the bad weather, and as 

 in the month of July swallows are always more 

 numerous than in other months and pass in ficx;ks 

 northward, I fear the mortality to swallows in South 

 America must have been very great. The deaths were 

 the result of the lack of insects rather than of the cold. 



Andrew Pride. 



3 Town Bank Road, Ulverston, July 26. 



Earthworms Drowned in Puddles. 



Anglers use earthworms, and worms found in the 

 little heaps of mud-scrapings on country roads are 

 specially valued as being of a fine, delicate pink colour, 

 clean and tough. I have heard anglers in North 

 Wales say that no worms were so good, especially 

 for sea-trout. But since road-tarring became so 

 general the phenols ( = carbolic acid) dissolved out of 

 the tar by rain destroy the worms. Unfortunately, in 

 numberless cases the trout have also been destroyed, 

 adult fish as well as fry, and American experiments 

 have proved that the spermatozoa of fish are killed 

 by carbolic acid from tar even when so diluted as to 

 be almost undetectable by any test. 



R. B. Marston. 



19 Adam Street, Strand, August 7. 



The Neglect of Science. 



A LADY called on me to-day saying she had been 

 sent by the sanitary inspector of a large town a few 

 miles from Manchester with specimens of a little 

 winged beetle (Niptus hololeucus), which she and 

 the inspector thought might be bed-bugs. 



Is it not extraordinary that those who are placed 

 in posts of great responsibility in sanitary matters 

 are so ignorant of their job that they cannot dis- 

 tinguish a flat wingless bug from a harmless and 

 almost spherical beetle? 



I wonder how much money has been wasted in 

 unnecessary fumigation and the destruction of 

 bedding by the crass ignorance displayed by sani- 

 tary inspectors of the elements of the natural history 

 of their calling. Sydney J. Hickson. 



The University, Manchester, August 11. 



