32 



NATURE 



[March 8, 1917 



upon the Board of Agriculture and Fisheries for 

 securing the use of unoccupied land for purposes of 

 food production. 



In view of the difficulty of securing delivery of 

 basic slag, superphosphate, and other phosphatic 

 manures, the President of the Board of Agriculture 

 and Fisheries asks farmers not to apply phosphates 

 to meadows and pastures during the remainder of the 

 present season. All available supplies should be re- 

 served for other crops, especially for roots and pota- 

 toes. Having regard to the short supplies, it is not 

 advisable to apply more than three-fourths of the 

 usual dressings of these phosphatic manu'-es, since 

 better resufts may be expected from the same total 

 weight of manure if the whole area under any par- 

 ticular crop is manured lightly than if a part is 

 heavily dressed and the balance left without artificial 

 manure. This rule applies only where the land is 

 uniform in quality. In those cases in which farmers 

 know that certain fields are poorer than others the 

 manurial treatment must be adapted to the special 

 conditions. Where land in good condition can be 

 given full dressings of farmyard manure, artificial 

 phosphatic manures may often be omitted without 

 materially reducing the crops. 



At the meeting of the Society of Glass Technology, 

 held at the University of Sheffield on February 15, 

 some samples of glass manufactured from British 

 sands were exhibited by Mr. C. J. Peddle, but the 

 principal business of the meeting was the discussion 

 of the effect of the temperature at which the annealing 

 of glass is carried out on the time required by the 

 process. Contributions to the discussion were made 

 by Mr. F. Twyman, of Messrs. Adam Hilger, Ltd., 

 London, and by Mr. S. English, of the Glass Tech- 

 nology Department of the University of Sheffield. As 

 the temperature is raised towards the softening point of 

 the glass, the speed at which the internal strains dis- 

 appear is increased, and the object is to find for each 

 type of glass the highest temperature at which it is 

 safe to carry out the annealing process. The observa- 

 tions are conveniently made on a glass rod mounted 

 between Nicol prisms, so that light passing through 

 the system shows the rings and cross characteristic 

 of a uniaxial crystal. As the annealing proceeds the 

 rings disappear, and the times of disappearance of the 

 last four rings were found in a particular sample of 

 glass to be as follows : At 500° C. 1230 minutes, at 

 550° C. 50, at 600° C. 20, and at 625° C. 12. These 

 temperatures are all considerably below that of actual 

 softening of the glass. 



Vol. xii. of "Contributions from the Jefiferson 

 Physical and the Cruft High-tension Electrical 

 Laboratories of Harvard University " for the year 

 19 15 consists of reprints of nineteen papers, the out- 

 come of researches aided financially by the Coolidge 

 fund for research, the Bache fund of the National 

 Academy of Sciences, and the Rumford fund of the 

 American Academy of Arts and Sciences, The volume 

 extends to 400 pages, and is a record of which Har- 

 vard may well feel proud. The Cruft laboratory pro- 

 vides two of the nineteen papers — one by Mr. F. 

 Cutting on the design of radiotelegraphic trans- 

 formers, another by Mr. E. L. Chafifee on coupled 

 circuits. O^. the Jefferson laboratory contributions, 

 that of the director, Dr. T. Lyman, is of special 

 interest, as it extends the ultra-violet end of the 

 spectrum to wave-length 600 Angstrom units. Dr. 

 P. W. Bridgman's five valuable contributions occupy 

 a large share of the volume, and deal with the effect 

 of great pressures on the temperature and velocity 

 of transition of polymorphic forms of the same sub- 



NO. 2471, VOL. 99] 



stance into each other. Altogether, 150 substances- 

 have been examined, and it is unfortunate that the 

 polymorphic diagrams obtained show no tendency to 

 fall into simple types. The subject appears to be very 

 complicated, and Dr. Bridgman suggests that the 

 explanation of the great variety of behaviour of the 

 different substances must be sought in the actual 

 shapes of the atoms. 



A COPY of the Year-Book of the Scientific and 

 Learned Societies of Great Britain and Ireland, 19 16, 

 has been received from Messrs. Charles Griffin and 

 Co., Ltd. This, the thirty-third annual issue of a 

 useful work of reference, contains a record compiled 

 from official sources of the work done in science, 

 literature, and art during the session 1915-16 by 

 numerous societies and Government institutions. The 

 list of societies dealt with is remarkably comprejien- 

 sive; but the plan of selection is not always clear. 

 Under the section entitled Psychology, for instance, ' 

 space has been found for particulars of the Nature 

 Study Society and the School Nature Study Union, 

 but nowhere in the volume have we found data con- 

 cerning the work of say, the .Association of Public- 

 Sg^ool Science Masters. ' Similarly, under the section 

 Literature and Hist^ory, the English Association is 

 Included, while the Historical Association is over- 

 looked. The man of science, however, will find the 

 volume as useful as ever In discovering the work done 

 in his particular subject during the year under review. 

 The book Is published at js. 6d. net. 



An Interesting and very full botanical catalogue 

 (New Series, No. 77) has just been issued by Messrs. 

 J. Wheldon and Co., 38 Great Queen Street, W.C. 

 It comprises floras of all countries, and is arranged 

 most conveniently according to the countries dealt 

 with. Many of the works are scarce. We notice that 

 several belonged to the late Sir Joseph Hooker. 



Prof. Eraser Harris writes to correct an error 

 made by him in his letter In Nature of January iS 

 (p. 389) on the introduction of the term "metabolic." 

 He referred to the first edition of Foster's "Text-book 

 of Physiology" as having been published In 1883, 

 whereas It appeared in 1877. 



OUR ASTRONOMICAL COLUMN. 



Effect of Haze on Solar Rotation Measures. — 

 Attention has previously been directed to Mr. De 

 Lury's suggestion that the apparent variations In the 

 rate of solar, rotation, as determined by the spectro- 

 graphlc method at different times, and from different 

 lines, might be accounted for by variations in the 

 haziness of the sky (Nature, vol. xcvili., p. 99). Messrs. 

 St. John and Adams have since made observations to 

 test the possible influence of haze, and have found 

 that to obtain equality of density in photographs of 

 the spectra at points just outside and just within the 

 sun's limb, it was necessary to give exposures In the 

 ratio of 100 to i. These observers concluded that, 

 under the usual working conditions at Mt. Wilson, 

 scattered radiation is a negligible factor, and Is not 

 a probable source of error in the observations of solar 

 rotation (Journ. R.A.S., Canada, vol. x., p. 553). In a 

 further note on the subject {ihid., vol. xl., p. 23) Mr. De 

 Lurv points out that the density of a negative Is pro- 

 portional to a power of the time, usually within the 

 range o-6 to 09, and that equal densities with a ratio 

 of 100 In the times of exposure would correspond to 

 a ratio of scattered light to limb light ranging from 

 6-3 to 1-6 per cent. A probable value would be about 

 4 per cent., which would produce about half the effect 

 noted in the Mt. Wilson observations, and, allowing 



