376 



NA TURE 



[August 20, 1908 



secondary stations, seven being of tlie first order. The 

 report contains the daily meteorological observations made 

 at all these stations during 1905. At the first- and second- 

 order stations the observations are made six times a day ; 

 at the third- and fourth-order stations twice a day. The 

 data are collected into monthly batches, but although the 

 monthly means are there, they are not brought togiither 

 so as to form annual summaries for the various stations. 



In a letter we have received from Mr. H. H. Scott, 

 meteorological observer for Launceston, Tasmania, some 

 interesting observations on the sinking of stones are re- 

 corded. In the course of the day Mr. Scott twice traverses 

 in full daylight a piece of public land between two thermo- 

 meter screens. Much of the surface of this land is charged 

 with brick dust, and on it fragments of diabase have been 

 scattered. In the absence of frost the path between the 

 screen remains firm and compact. During June last 

 twenty-one of the first twenty-nine days commenced with 

 frost, and outside thermometers read as low as i9°-3 F. 

 Later in the day bright sunshine followed, and the read- 

 ing of the solar thermometer sometimes reached 101° F. 

 Consequently, the ground was first frozen, then soaked 

 with moisture, and afterwards warmed considerably. Mr. 

 Scott noticed that day by day the earth round the frag- 

 ments of diabase appeared to be lifting slowly. On 

 June 29 he found some fragments to be 18 mm. to 20 mm. 

 below the surrounding surface, and in the case of un- 

 usually large pieces of rock even deeper. No earthworms 

 were at work in the neighbourhood of the stones, and the 

 alteration in level appeared to be due wholly to atmo- 

 spheric agency. 



In the " Album der Natuur " Dr. J. G. van Devenlcr writes 

 on the Warner Powrie method of colour photography, and 

 refers to an article in Nature, October 24, 1907 (vol. Ixxvi., 

 p. 642). In this method, coloured lines replace the coloured 

 dots of the Lumifere process, about 320 lines being the 

 average to the centimetre. The advantages are that the 

 colour screen is more regular with alternating colour- 

 bands, and that positive prints can be made on paper. 

 The colour screen is prepared from bichromatised gelatin 

 by e.Kposure under a screen of bands divided by spaces 

 half their width. The resulting ridges of gelatin are 

 stained with appropriate dyes, and then present a series 

 of coloured bands of which the relative thicknesses are 

 as I, 2, and 3 for the colours violet, green, and orange, 

 the absolute thickness varying from 5 to 40 microns. 

 Sensitive emulsion is then deposited over this screen, and 

 a transparent positive obtained as with the Lumi^re method. 

 To obtain further positives, use is made of the already 

 known Uto paper. In this the sensitive layer is mixed with 

 three organic dyes complementary to those in the screen, 

 and mi.\ed with anethol. This gives the property that 

 the absorption of a colour causes the same coloured dye 

 to become colourless. In this way a positive coloured 

 print is obtained. Dr. Deventer does not think that 

 ordinary Uto paper containing silver can be used. He 

 shows how Powrie uses two mirrors at an angle of 110° 

 with a thin glass plate between the positive plate and the 

 paper, obtaining the combination empirically which results 

 in giving the best intensification and elimination of any 

 dark bands. The paper ends vyith a description of the 

 method of obtaining the cliches for three-colour printing. 



We have received new catalogues of electrical and other 

 apparatus from Messrs. Siemens Bros, and Co. and from 

 the Cambridge Scientific Instrument Co. which should 

 prove useful to those who are considering the purchase of 

 apparatus for the coming winter. The latter catalogue is 



NO. 2025, VOL. 78] 



in the form of a file, with an arrangement at the end to 

 enable sheets issued in the future to be readily attached. 

 It also gives more information about the sensitiveness of 

 the various instruments described than we have seen 

 previously in any instrument maker's catalogue. 



The attempts which have been made in the past to 

 substitute some instrument for the eye in accurate photo- 

 metry have not been very successful owing to the methods 

 adopted not having proved so sensitive as the eye. M. 

 Charles F^ry appears to have overcome this difficulty by 

 an arrangement he described to the Soci^t^ frangaise de 

 Physique in May, which is given in the August number 

 of the Journal de Physique. The light to be tested is 

 placed a metre away from a lens, which forms an image 

 of the source on the receiving disc of a Boys radiomicro- 

 meter. Between the lens and disc the light passes through 

 a layer of water 4 cm. thick, containing copper acetate 

 of such strength that there is i gram of copper in a litre ' 

 of solution. This solution, the author finds, cuts out of 

 the beam those radiations which do not affect the eye, and 

 the instrument gives results for different .sources which 

 are in close agreement with those given by the Lummer- 

 Brodhun photometer. It also enables the optical efficiency 

 of the source, i.e. the ratio of the luminous to the total 

 radiation, to be readily found. 



Prof. J. C. McLennan, University of Toronto, described 

 in Nature of May 14 (p. 29) some experiments which led 

 him to conclude that the radio-activity of potassium and 

 its salts is not connected with a normal atomic property 

 of the metal. The salts used were those ordinarily sold 

 by the best makers as chemically pure, and in arriving at 

 the conclusion mentioned it was assumed that the salts 

 used possessed, at least approximately, the high degree of 

 purity claimed for them. Prof. McLennan now writes to 

 say that analysis has proved this assumption to be in- 

 correct. A comparison of the percentage by weight of 

 potassium in several salts with the radio-activities of the 

 salts has shown that the salts which contained the most 

 potassium were those which exhibited the strongest activity, 

 and that for the more active ones the radio-activity was 

 almost directly proportional to the amount of potassium 

 present. 



Messrs. Crosby Lockvvood and Son send us the first 

 number of a quarterly circular of engineering and technical 

 literature (classified under subjects) just published by them. 

 The circular contains particulars of the most important 

 works in engineering, science, and technology published 

 during the past three months in England and in America, 

 and as it will be repeated every quarter it should prove 

 of assistance to engineers. 



The nineteenth annual general meeting of the Institu- 

 tion of Mining Engineers will be held at Edinburgh on 

 .September 2-4. The following papers will be read, or 

 taken as read : — coal-dust to date and its treatment with 

 calcium chloride, H. Hall ; on the practical use and value 

 of colliery rescue-apparatus, G. Blake Walker ; the Wcmyss 

 coal-field, J. Gemmell ; the working of oil-shale at 

 Pumpherston, W. Caldwell; deep diamond boring, J. 

 Thomson. 



In the Bulletin of the Johns Hopkins Hospital for Julv 

 (xix.. No. 208), Prof. Howard Kelly, in an article entitled 

 " The Barred Road to Anatomy," gives an interesting 

 account of the " body snatchers," Burke and others, and 

 of the times in which they lived, from the point of view of 

 the study of anatomy. 



