432 



NATURE 



[January 31, 1918 



In the Austraiian Zoologist (vol. i., part 4, Svdnev, 

 October 8, 1917) there is an interesting article by Mr. 

 Charles Hedley, director of the Australian Museum, 

 on the economics, of 'I'mchus niloticus. This hand- 

 some shell was mistaken for a product of the Nile by 

 Aldrovandus, who, in 1606, was the first writer in 

 Europe to describe it. Mr. Hedley tells us that it is 

 found on coral-reefs from Ceylon to Samoa, and as 

 far north as Japan. The natives of various islands 

 make use of the animal as food, and the periphery of 

 the shell has been cut out and worn as a bracelet by 

 the Papuans. But amont,' civilised people it was only 

 known to shell fanciers until a few years ago. " Ex- 

 haustion of former supplies of pearl shell and the 

 increasing demand of r< cent years have promoted search 

 for new sources of mother-'of-pearl. Thus Trochns 

 niloticus, or trocas, as it is sometimes called, having 

 dense firm Tiacre, which proved good material for 

 buttons, came to be exploited by manufacturers. Dur- 

 ing the past six years an active request for Trochus 

 by button-makers has sprung up, advancing from 

 20Z. to 30/.. a ton." The Great Barrier Reef 

 is being fished for Trochus, from Torres Straits 

 southwards to Port Mackay. The export of Trochus 

 from Queensland in 1915 was 544 tons, worth i2,oooZ., 

 and in 1916 was 950 tons, worth 23,oooZ. The Philip- 

 pine Islands export about 320 tons annually. From 

 Western Australia the exports of Trochus were : — For 

 1912, 52 tons; for 1913, 66 tons; for 1914, 1-9 tons; 

 for 1915, 73 tons; for 1916, 26 tons. There are also 

 large fisheries in New Guinea, the Solomon Islands, 

 and Fiji. Some Japanese fishermen carefullv save 

 both meat and shell. From ten tons of f,hell a ton 

 of meat is obtainable, worth, in China, 20L a ton, 

 •Mr. Hedley considers that the annual Australian crop 

 of .Trochus is likely soon to deteriorate under the 

 present active fishery. 



The annual report of the Department of Agriculture, 

 Nyasaland, for the year ending March 31, 1917, con- 

 tains much interesting matter. The exports of tobacco, 

 tea, and cotton constitute a record for the Protectorate, 

 and the past year has been particularly favourable for 

 agriculture generally, despite the difficulties arising 

 out of the war and the absence of many planters on 

 military service. The increased demand for tobacco is 

 a direct result of the privileged admission of British- 

 grown tobacco into the United Kingdom, and, despite 

 high prices for freight, the industry is very prosperous, 

 and has now established itself in the home market. 

 Nearly 1000 more bajes (400 lb.) of cotton were exported 

 than in the previous year, and the acreage under 

 European cultivation is now 29,580. Tobacco 

 first appeared as an article of export in 1899, and, 

 despite freight charges, has managed to establish itself 

 against American competition. Tea to the extent of 

 420,685 lb. was exported, whilst in the previous year 

 the amount was 288,341 lb. The great difficulty with 

 regard to Nyasaland products is that of freight and 

 transport, and much damage to cotton and tobacco 

 results during the dilificult journey to the coast. There is 

 also the drawback that owing to delays the planter can 

 seldom realise on his crops within one year of the date 

 of shipment, thus necessitating double capital, or plant- 

 ing on advance rates, which eat deeply into profits. 

 Until direct railway communication with the coast can 

 be established this promising land will remain very 

 severely handicapped. 



The Scientific Atnerican, in its issue of December 22 

 last, directs attention to the low efficiency ot massed 

 rifle fire at ranges less than 500 yards. It appears that 

 the best results ever obtained were by the Boers at 

 Colenso, when in full daylight and from a sheltered 

 position they succeeded in making one hit in 600 shots 



NO. 2518, VOL. 100] 



fired against an enemy thoroughly exposed in the 

 open. This lack of success of the rifle at close ranges^ 

 leads to its being regarded rather as a handle for a 

 bayonet than as an effective weapon itself. It seems 

 that no amount of preliminary training or of adjust- 

 ment of sights can eradicate the tendency of the rifle- 

 man to shoot too high when under mental stress. To 

 overcome this difficulty Col. Ely, of the American 

 Army, has invented an :)ttachment weighing only 2 oz. 

 which, when adjusted, prevents the rifle being dis- 

 charged when its angle of elevation exceeds a given 

 value. The records obtained with the device are about 

 twent3'-four times as good as the Colenso results, but 

 it does not appear to have been adopted by the American 

 military authorities. 



The importance of modern methods of welding in 

 enabling repairs to be executed quickly has been 

 brought out by a recent account in Engineering (Janu- 

 ary 11) of the methods adopted for making good the 

 damage done by the Germans on vessels interned in 

 U.S. ports. The principle of electric welding has been 

 applied to fifteen ships in the port of New York, and 

 all these are now in commission and probablv 

 ready for service. Bulletin No. 98 of the University 

 of Illinois Engineering Experiment Station is also of 

 interest, and gives an account of tests of oxyacetvlene 

 welded joints in steel plates. The plates employed 

 varied in thickness from No. 10 gauge to i in., and 

 were subjected to various heat treatments. The tests 

 include static loads, repeated loads, and impact. The 

 welds were made by skilled workmen For joints with 

 no further treatment after welding, the joint efficiency 

 for static tension was found to be about 100 per cent, 

 for plates up to J in. thick, and to decrease for thicker 

 plates ; these joints show an efficiency not greater than 

 75 per cent, for the material in the joints, but were 

 strengthened by working the metal after welding and 

 weakened by annealing at 800° C. Repeated 

 stress tests followed in a general way the results of the 

 static tests. Hammering or drawing the weld while 

 hot increases the strength. The impact tests show 

 that oxyacetvlene welded joints are decidedly weaker 

 under shock than is the original material ; for joints 

 welded with no subsequent treatment, the strength 

 under impact seems to be about half that of the mate- 

 rial. If the welded joint is worked while hot, the 

 impact-resisting qualities • are slightly improved. 

 .\nnealing from 800° C. seems to have very little effect 

 on the impact-resisting qualities. 



Messrs. H. K. Lewis and Co., Ltd., hope to pub- 

 lish in the course of the next few weeks vol. i. of 

 '■ Regional Surgery," a work by American and British 

 authors, in three volumes, edited by Dr. J. F. Binnie, 

 Gould's "Pocket Medical Dictionary," Stitt's "Tropical 

 Diseases," and Stitt's " Practical Bacteriology." Tiir 

 first consignment of these books was lost at sea b\ 

 a gale. 



Tin-: twentieth issue of "The Scientist's Reference, 

 Book and Diary "■ — that for 1918 — ^has now been pub- .^ 

 lished by Messrs. Jas. Woolley, Sons, and Co., Ltd.-, ' 

 of Manchester, at the price of 2s. 6d. As usual, it 

 consists of two parts : the first is a storehouse of 

 physical and chemical constants, definitions, and im- 

 portant scientific facts ; and the second is a conveniently 

 arranged diary and memorandum book. The two are, 

 bound together in a leather case suitable for carrying 

 in the pocket. 



The following books are announced for publication ' 

 during Februarv bv Messrs. Chapman and Hall, 



Ltd. :— "The Chemistry of Colloids," by Prof. R. i 



Zsigmondy, translated by Prof. E. B. Spear, part ii., ^ 



