December 31, 1914] 



NATURE 



489 



process is particularly interesting, as detailed records 

 of the production of cast-iron in furnaces of such a 

 primitive type are not numerous. The industry is ver}- 

 evidently Chinese in its origin, and it seems obvious 

 that it owes little or nothing to European influences. 



During the forced rest from his usual busy, scien- 

 tific work Dr. H. R. Mill recently spent three and a 

 half months in New Zealand, and visited the meteoro- 

 logical stations between Stewart Island, in the south, 

 and the Bay of Islands, in the north, in which he 

 was assisted in every way by Mr. D. C. Bates 

 (Dominion Meteorologist) and others. He has embo- 

 died his impressions and notes obtained of the climate 

 in an interesting article, untrammelled by tables or 

 diagrams, in Symons's Meteorological Magazine' for 

 December. Among many other matters, he points 

 out that although Great Britain lies nearer the pole 

 than any part of New Zealand, the climates are much 

 alike, summer in the South Island being apparently 

 no warmer than in England; the lower latitude, how- 

 ever, ensures a greater intensity of sunlight, and 

 vegetation proves that the mean temperature of winter 

 is much higher than Great Britain. The prevailing 

 wind being westerly, the mountains receive a rainfall 

 exceeding loo in. in many places, while on the east 

 much of the area has an average of less than 20 in. 

 The climate of the North Island is decidedly warm in 

 summer, and there is a marked contrast between the 

 two seasons. Great faith is attached to the weather 

 forecasts ; weather conditions being simpler the prog- 

 nostics are less liable to misinterpretation than in 

 Western Europe. Changes and movements of clouds 

 appear to be more expressive of weather changes than 

 in this country, and much use is made of them in 

 filling up the gaps in telegraphic reports. 



In the Comptes rendus of the Paris Academy of 

 Sciences for November 30 M. Colardeau describes an 

 X-ray method of localising foreign bodies imbedded 

 in the tissues. The matter is of special importance 

 at the present time on account of the war, and during 

 the past few months many suggestions have been 

 made. The Rontgen Society, under the presidency of 

 Sir Alfred Pearce Gould, has already devoted its 

 December meeting to the question, and a further 

 discussion is arranged for January. M. Colardeau 's 

 method differs but slightly from the plan introduced 

 some years ago, and now almost universally adopted 

 with the addition of minor improvements, by Sir 

 James Mackenzie Davidson. 



The Journal of the Washington Academy of 

 Sciences for December i contains an abstract of a 

 paper bv Mr. L. W. .Austin, of the Naval Radio-tele- 

 graphic Laboratory-, on quantitative experiments in 

 radio-telegraphic transmission. The signals were sent 

 from the station at Arlington, Virginia, which uses 

 the Fessenden rotary gap giving an antenna current 

 of 100 amperes and a wave-length of 3800 metres. 

 The aerial is triangular with a mean height of 400 ft. 

 Short-range experiments showed that owing to in- 

 sufficient conductivity of the soil the effective height 

 of the antenna was only 200 ft. The strength of the 

 signals was determined by the shunted telephone 

 NO. 2357, VOL. 94J 



method on board the U.S.S. Birmingham on a voyage 

 to Gibraltar and back. The effective height of the 

 receiving antenna was 114 ft., and the effective resist- 

 ance 50 ohms. For distances between 300 and 2000 

 miles the strength, !«, of the received signals could 

 be expressed by the equation lR = (i2o»r^^Kl.«.A^R) 

 exp. (-00015^ V^), where //s and //« are the effec- 

 tive heights of sending and receiving antennae, !<, the 

 sending antenna current, A the wave-length, d the 

 distance of the stations apart, and R the resistance of 

 the receiving system. This is a slight modification 

 of the theoretical expression given by Sommerfeld. 

 The complete paper will be published in the Bulletin 

 of the Bureau of Standards. 



Messrs. Burroughs Wellcome and Co., Snow 

 Hill Buildings, have sent us a copy of the Wellcome 

 Photographic Exposure Record and Diarj- for 1915, 

 which is a neat little pocket-book with a strong canvas 

 cover. Having been issued for several years, and 

 each year revised and brought up to date, it is now 

 the most compact essence of photographic information 

 — a veritable "tabloid." If you want to know how 

 to tone bromides green, how much flashlight powder 

 to use, about night photography, about speeds of 

 papers and plates, and about a host of other require- 

 ments of the photographer, whether amateur or pro- 

 fessional, you have only to look into this pocket-book 

 where the information is dealt with clearly, tersely, 

 and accurately. Practical experience of practical men 

 is embodied in these pages, and the experience culled 

 by experiments and long practice is analysed and 

 set forth in simple formulae and precise directions, not 

 only helping the beginner, but saving him time, 

 trouble, and material. The Wellcome Exposure Cal- 

 culator, fitted ingeniously in the inside of the back 

 cover, has only to be used once to be used always. 

 By one turn of the scale the correct exposure for any 

 plate or film is immediately given for any time of day 

 or year. Blank forms are given for the entrv^ of all 

 details about each photograph taken, and these are 

 followed by a diarj- for entry of ordinary daily memo- 

 randa. The book is issued in wallet form, complete 

 with pencil, and three editions are published, suitable 

 for the northern hemisphere, the southern hemisphere, 

 and the United States. It is a cheap shillingsworth, 

 and every photographer should invest in one. 



Five short papers on audible and other cab signals 

 on British railways were read and discussed at the 

 Institution of Mechanical Engineers on December 18. 

 These papers express the opinions of engineers con- 

 nected with, and describe experiments which have 

 been in progress on, the Midland, Caledonian, North- 

 Eastern, Great Western, and Metropolitan Railways. 

 It is generally admitted that the present system of 

 semaphores and lamps is not entirely trustworthy, and 

 it is hoped that some standard system of cab signal- 

 ling which will be effective may be evolved soon. As 

 was pointed out by Mr. Blackall, of the Great Western 

 Railway, it is very important that some standard 

 should be conformed to, so that the engines belonging 

 to one railway passing over to the system of another may 

 be able to pick up the signals which would ordinarily 

 be given to the engines belonging to the latter system. 



