December 18, 1902] 



NA TURE 



157 



in the Engineering School of Valentino. His writings deal 

 with agricultural chemistry, mineralogy and electro-chemistry, 

 and his name has been perpetuated in the mineral Cossaite. 



Mr. E. Ernest Lowe, curator of the Plymouth Museum and 

 Art Gallery, sends a description and sketch of a portion of a 

 mammalian tooth found by Mr. F. Leslie Sara, of Velverton, 

 in a cave in the Mendip Hills, Somersetshire. Mr. Lowe 

 has identified the object, the greatest length of which is 

 nearly six inches, as the terminal portion of one of the lower 

 canine teeth of Hippopotamus ampkibius. "The grinding 

 surface of the tooth," he remarks, "is closely striated, and in 

 the centre the strke are so close and deep as to form a distinct 

 groove, whereas all the recent hippopotamus teeth I have been 

 able to examine have a smooth grinding surface. At the point 

 of the tooth, the enamel is chipped as if from a blow. At first 

 sight, the specimen appears to have been cut from the complete 

 tooth with a modern saw, but I am assured it is exactly as 

 found. The cut end was exposed on the surface of the clayey 

 ground." Mr. Lowe suggests that the tooth is a prehistoric flint- 

 flaker or axe-head of a unique character, but an authority to 

 whom we have submitted the matter informs us that fossil 

 hippopotamus tusks exhibit a structure exactly similar to that 

 described by our correspondent. It is due to disintegration of 

 the ivory along the lines of growth. 



In the Journal ai the Society of Arts for December 5, there 

 s a paper by Mr. Alfred Watkins on some aspects of photo- 

 graphic development, setting forth the methods of work that 

 have become associated with the author's name. A few 

 observations recorded appear to be new, as, for example, that 

 an increase of iodide in a rapid emulsion may increase the 

 multiplying factor for development, and that a little iodide of 

 potassium in the developer causes the image to appear almost 

 as quickly at the back of the plate as at the front. The 

 tendency appears to bi to find new circumstances that interfere 

 with the most usual course of events in development, and from 

 the discussion that followed the paper we gather that at least 

 some authorities still regard Mr. Watkins's generalisations as of 

 rather too sweeping a character. 



Dr. G. Hellmann has recently published the sixth of his 

 useful discussions of the rainfall of the Prussian States, prepared 

 at the request of the German Meteorological Office. The part 

 now in question refers to the Provinces of Schleswig-Holstein 

 and Hanover; the annual distribution of rainfall is clearly 

 delineated, as before, on a coloured map showing the amounts 

 for each 50 millimetres from 450 to 1400, and upwards, with an 

 inset exhibiting the interesting values for the district of the 

 Hartz Mountains. Particular attention is given to the greatest 

 falls in one day, and shorter intervals, as being of considerable 

 utility to engineers and others. The variations in the annual 

 amounts at the same localities are, as usual, very considerable, 

 and depend upon laws of which little is known at present, the 

 rainfall of a wet year being occasionally double the amount of 

 that in a dry year. 



We have received vol. xi. of Deutsche Hberseeischc meteorolo- 

 jgiscke Beobacktungen, published by the Deutsche Seewarte, 

 containing the meteorological observations made in German 

 East Africa, collected and discussed by Dr. H. Maurer. The 

 observations were made at thirty-three stations ; some of them 

 •date back as far as 1S94, and some hive been published in 

 other places. Although the series is not complete and the 

 observations are acknowledged to be not all of the same quality, 

 they give, in the main features, a useful representation of the 

 climate of a large district hitherto but little known. In bringing 

 the data together in one volume, by very carefully collating 



NO. I729, VOL. 67] 



them on the moit approve 1 plin and by giving full particulars 

 of the stations and instruments, the Seewarte has rendered a 

 great service to meteorological science. 



Mr. Frederic J. Cheshire describes, in the Journal o{ the 

 Ouekett Microscopical Club, a simple form of reflecting 

 polariser. It consists of a single glass reflecting surface fixed at 

 a constant angle of 33^° with the axis of the microscope in the 

 position commonly occupied by the mirror, and capable of 

 rotation about that axis without varying the inclination. The 

 author points out the advantage of the increased field as 

 compared with that obtained with a moderate sized Nicol's 

 prism. 



The November issue of the Journal of the Franklin Insti- 

 tute contains an interesting pip.r on the conversion of amor- 

 phous carbon to graphite, by Mr. F. J. FitzGerald, chemist 

 to the Acheson Graphite Compmy. The paper is largely 

 historical, the experiments of Despretz, Berthelot, Moissanand 

 others being described in some detril. 



Shortly after the great Indian earthquake of June 12, 1897, 

 a duplex pendulum seismograph was erected at Shillong, a town 

 lying just within the epicentral area of the earthquake. The 

 records of this instrument from August, 1897, to the end of 1901 

 have recently been examined by Mr. R D. Oldham in order to 

 ascertain if any traces of tidal influence were to be detected in 

 the occurrence of shocks in what at that time was an extremely 

 unstable portion of the earth's crust. Mr. Oldham arrives at 

 the following conclusions, which, however, he regards as 

 provisional and requiring verification from a more extended series 

 of observations. There is, in the first place, a large variation 

 in the diurnal distribution of earthquakes, maxima of frequency 

 occurring between 10 and 11 p.m. and between 6 and 7 a.m. 

 Superimposed on this large but unexplained variation in 

 frequency, there is a smaller variation, which has the appearance 

 of being due to the tidal stressesset up by the attractionof the sun. 

 Also, if this smaller variation is really due to tidal stresses, then 

 the horizontal stress is much mne efHcie.it than the vertical 

 stress, and the effect is less due to the amount of the stress than 

 to the rate and range of its variation. 



A reconnaissance-survey of Jebel Garra and the oasis of 

 Kurkur, which lie to the west of Assuan and the first cataract 

 on the Nile, has been made by Dr. John Ball (Survey Depart- 

 ment, Public Works Ministry, Cairo, 1902). Jebel Garra (540 

 metres above sea-level) is a huge, flat-topped hill capped by 

 Eocene limestone, which stands on the margin of the plateau 

 and scarps of Upper Cretaceous strata bordering the Kurkur 

 Oasis. These overlook the low, undulating country formed of 

 Nubian sandstone which occupies the intervening desert, where 

 much blown sand occurs. The Kurkur Oasis is formed by the 

 confluence of several wadies or drainage-channels, which have 

 no outlet, and it contains two wells. There is little hope of the 

 oasis being able to maintain more than a few human beings, and 

 at present there are no residents. The water occurs at an 

 altitude of 330 metres, and it appears to be derived rather from 

 local rain water, which drains through the Cretaceous white lime- 

 stone, than from any more permanent underground supply. 



AN analysis by Mr. Radcliffe Hall of the volcanic dust which 

 fell at Barbadoes on October 16 agrees in a general way with 

 Dr. Pollard's analysis of the dust of May 7 (see Nature, 

 June 5). The material analysed by Mr. Hill contained rather 

 more alumina and alkalis than that analysed by Dr. Pollard, 

 and less magnesia ; facts which point to the conclusion that 

 felspar and possibly also glass are more abundant in the 

 October than in the May dust. 



