June i, 192 1] 



NATURE 



437 



doing considerable damage of late years to young 

 plantations of Douglas fir in many parts of Scotland. 

 This either kills the leading shoot a few inches below 

 the tip or causes the death of the whole tree by 

 attacking the outer tissues completely round the stem 

 at a little distance above ground-level. In both cases 

 there is a sudden decrease in diameter in passing from 

 the healthy to the diseased portion of the stem, accom- 

 panied by much exudation of resin. This fungus is 

 •described as a new species, Phomopsis pseiidotsugae, 

 by Dr. Malcolm Wilson in the Transactions of the 

 Royal Scottish Arboricultural Society (vol. xxxiv., 

 part ii., pp. 145-49, plates iv.-v.) published in Novem- 

 ber last. Early recognition of the disease and burn- 

 ing of afTected trees are the measures recommended 

 for stamping out this pest, which has been known to 

 kill half the trees in a young plantation. 



A LENGTHY paper on "The Perishing of Paper 

 in Indian Libraries " forms part vii., vol. jii., 

 of the Journal of the Indian Institute of Science. 

 The investigation was undertaken at the Institute of 

 Science on behalf of the Government of India by Mr. 

 J. J. Sudborough and Miss M. M. Mehta. "Perish- 

 ing " is defined as a brittleness which is so marked 

 that folding the paper once or twice will cause it to 

 break along the fold, and it is observed in many of 

 the books in record oflfices and libraries. The con- 

 clusions which the investigators have arrived at as 

 the result of an examination of numerous libraries in 

 India do not differ greatly from the report of the 

 •Committee on the Deterioration of Paper in Europe 

 published in the Journal of the Royal Society of Arts 

 for 1898 (No. 46), or from the report of a similar 

 committee in America which appeared as Report 

 No. 89, Pub. 1909, U.S. Department of Agricul- 

 ture. Chemical perishing, as distinct from the 

 destruction caused by micro-organisms, was inves- 

 tigated, and the conclusion arrived at is that the 

 former type of perishing, which is by far the com- 

 moner, is due to hydrolysis of the cellulose molecules 

 ■of the paper and their later decomposition into simple 

 substances rather than to a process of oxidation. The 

 type of paper found to be most resistant in India is 

 a rag-paper the fibres of which have not been 

 weakened in the process of manufacture. Treatment 

 which has been found to damage the fibre is pro- 

 longed digestion with alkali, over-bleaching, non- 

 removal of the last trace of bleach by antichlor, and 

 imperfect washing that leaves traces of acid in the 

 paper, while rosin and filling material should not 

 •exceed a small fi.xed percentage. It is recommended 

 that all books and documents of permanent value 

 should be removed to libraries in hill stations with 

 temperate climates or placed in special buildings in 

 which complete air control can be maintained. 



Several distinctive features are erhbodied in a new 

 model radioscopic couch by Messrs. Newton and 

 Wright, Ltd. The tube-box, which is fitted with a 

 liolder to take a gas tube or Coolidge tube, is covered 

 by sheet-lead and mounted upon steel rails, free move- 

 ment being ensured by ball bearings The diaphragm 

 is of the rectangular type, and is operated by levers 

 .attached to a control arm ; this latter projects hori- 



NO. 2692, VOL. 107] 



zontally from the tube-box, and is supported by one of 

 two metal uprights which hold the protective apron 

 in position. A further feature of interest is that these 

 uprights allow the tube-carriage to be shifted longi- 

 tudinally by the operator's knees, which should at 

 times be found a great convenience. Protective devices 

 figure conspicuously in this new model. 



Remarkable developments have taken place in the 

 use of water-power in many parts of the world during 

 recent years, with which English engineers who have 

 not time to consult foreign publications are unfamiliar, 

 and in which English manufacturers have taken but 

 little interest. The possibilities of development in 

 this country and in other parts of the Empire of the 

 sources of water-power are awakening an interest in 

 the subject, and the proposed issue by Messrs. Henry 

 Frowde, and Hodder and Stoughton, under the editor- 

 ship of Prof. S. M. Dixon, of a quarterly Journal of 

 Hydraulics, at an annual subscription of 31s. 6d., each 

 number of which will be self-contained and will 

 make available m a convenient form details of 

 the most recent developments of hydraulic engineer- 

 ing, should prove of interest and value to many en- 

 gineers. A sufficient number of guaranteed subscribers 

 is required before the first issue. 



Dr. Arne Westgren has carried out some Rontgen 

 spectrographic investigations of iron and steel in the 

 University of Lund, Sweden, and presented his results 

 at the May meeting of the Iron and Steel Institute. 

 He has verified Hull's result that iron at ordinary tem- 

 peratures (a iron) has a cube-centred cubic lattice struc- 

 ture, the edge of the unit cube being 287 A. He finds 

 that between 800° and 830° C. — that is, within the 

 so-called /3-iron range — the atoms are oriented in 

 exactly the same way as in o iron, the edge of the 

 unit cube being 292 A. If allotrophy is accepted as 

 being the same as polymorphy for solid crystalline 

 bodies, this means that jS iron cannot be considered 

 as a separate modification. On the other hand, both 

 in pure iron and in austenite at 1000° C. — that is, in 

 the Y range — the crystals have face-centred cubic lat- 

 tices, -the edge of the unit cube being 3-61 A. Con- 

 sequently, this is characteristic of y iron, and a funda- 

 mental crystallographic difference exists between a and 

 7 iron. In martensite, the constituent of hardened 

 carbon tool-steel, Dr. Westgren has found that the iron 

 is in the a form. This is also the case in high-speed 

 tool-steel hardened at 1275° C. The investigations are 

 being continued, and will be extended to include com- 

 plex phases in steel and other alloys. Spectrograms of 

 cementite show that its crystal structure is related to 

 that of 7 iron, a fact which explains the mutual 

 solubility of these phases. 



Lists Nos. 182 and 183 of the Cambridge and Paul 

 Instrument Co., Ltd., give particulars respectively of 

 the Cambridge microtomes and the Cambridge record- 

 ing clinical thermometers. The firm now manufac- 

 tures three types of microtomes. The universal 

 microtome, on a circular cast-iron base of 250 mm. 

 diameter, is constructed on similar principles to the 

 Cambridge "rocker," but has a wider range of applica- 

 tion ; it cuts sections of o-ooi to 0035 mm. in thick- 

 i ness from objects up to about 18 by 20 mm. in dia- 



