July 9. 1903J 



NATURE 



223 



if it could be established, would be evidence of tropical 

 origin. 



Following out Mr. Teall's suggestion, the Taormina 

 sample, and also the one from Bayham Abbey, have been 

 examined to see if any evidence could be obtained showing 

 the presence in them of aluminium hydroxide. A study of 

 the actions of solutions of caustic and carbonated alkalis 

 upon the dusts showed that both silica and alumina could 

 be dissolved from them by the former solvent ; but similar 

 results were also obtained from orthoclase and oligoclase, 

 whilst the treatment with sodium carbonate showed that no 

 large quantity of amorphous silica was present in either 

 of the specimens. The results are not conclusive, but, so 

 far as they go, they point to there being no uncombined 

 alumina in the samples. T. E. Thorpe. 



Dust Storms in New Zealand. 



An event of more than ordinary interest occurred here 

 last November, and seeing that it has a certain importance 

 not altogether restricted to us and our neighbourhood, I 

 have ventured to address you on the subject. 



From Invercargill, at the extreme south of the South 

 Island, it was reported on November 14 that in various parts 

 of the town and district tank water had a clayey appear- 

 ance, and exposed objects were covered with a fine dust or 

 mud. A similar report came from many places in the 

 south-east portion of the island, and inland as far as 

 Wakatipu, where heavy gales and thunderstorms are stated 

 to have occurred on that date. At Dunedin no sign of the 

 dust was visible during the day, but in the evening, from 

 8 to 10 p.m., the moon was at times obscured by clouds 

 of a reddish colour, but the weather kept dry and no dust 

 fell. At Waipawa, near the east coast North Island, a very 

 heavy dust storm commenced at 9 a.m. on November 15. 

 It lasted for several hours, extended, and became very 

 thick. It was not due to local causes. 



Samples of the dust examined by a local authority in 

 Dunedin were stated to be of volcanic origin, and possibly 

 connected with eruptions in Samoa or in South Victoria. 



Dr.^ Benham, of the Otago University, kindly gave me 

 a sample of the dust that fell at Otakaia^ a few miles south 

 of Dunedin. I submitted it to microscopical and chemical 

 examination with the following result : — 



The specimen was in a small bottle with water ; it had 

 fallen into a bucket which was quite clean, and in such a 

 position that contamination was impossible. The sediment 

 was of a reddish-brown colour, very fine in grain. A 

 mounted specimen examined with an |-inch objective showed 

 various vegetable cells, apparently portions of the feathery 

 pappus of fruits of composites and similar light inatter. 

 Small rounded grains of inorganic matter were frequent, in 

 some cases large enough (003mm. diameter) to depolarise 

 light. They were chiefly quartz, but some were apparently 

 augite, and others particles of weathered minerals coloured 

 red with iron oxides. To these last the colour of the dust 

 in mass was due. There were also in every preparation 

 observed several diatoms. In one preparation there was 

 a piece of vegetable tissue composed of fine cells. In all 

 there was much carbonised matter. A partial quantitative 

 analysis gave the following result after complete drying 

 in an air bath :— SiO^ 53-68, Al^Oj 1844, Fe,03 654, 

 CaO 095, MgO 1-52, K,0 258, Na,0 167. "Loss on 

 Ignition, 1460. Total, 9998. I have been unable to find 

 any analysis of dust borne any great distance by wind with 

 which to compare this. A partial analysis of dust col- 

 lected in Kngland, given in a March number of your paper, 

 does not differ much from this except that the loss on 

 ignition is 36-4, and the other constituents correspondingly 

 lower. 



There is no doubt that this dust was derived from a 

 desiccated surface ; the carbonised matter suggests that it 

 had been swept by fire, and as the weather all over New 

 Zealand had been very wet for weeks previously, there is 

 no possibility of a local origin of the dust. 



Since Australia had just previously, after a period of most 

 prolonged drought, suffered from the effects of severe gales, 

 I ausing dust storms that produced almost total darkness in 

 Melbourne and Sydney, it is natural to look to that conti- 

 nent for the origin of the dust storm. Through the kind- 

 ness of Prof. J. W. Gregorv, F.R.S., I was sent a specimen 



of dust that fell in Gippsland during a dust storm on 

 October 11, and this, though coarser, was so essentially 

 similar to our dust that a comparison of the two speci- 

 mens at once established the extreme probability of identity 

 of origin. 



The distance in a straight line from Melbourne to Inver- 

 cargill is 1200 miles, and to Dunedin 1300 miles, and from 

 Sydney to Waipawa 1300 miles. The origin of the dust 

 was probably some distance to the west of the Blue Moun- 

 tains. There seems, therefore, no doubt that this dust was 

 carried 1500 miles, 1200 of which was over a water surface. 



Your readers are doubtless aware that the climate of 

 New Zealand, and of Australia on its eastern seaboard, is 

 chiefly dependent on the passage of deep cyclonic disturb- 

 ances travelling in a general N.W.-S.E. direction. In 

 front of the centre of these the wind blows strong from the 

 N.VV., and behind the centre from the S.W. The baro- 

 metrical and weather records appended show that at the 

 date mentioned such a cyclonic disturbance of rather more 

 than the average intensity was experienced at the time of 

 the dust fall. 



In connection with this I may mention that after the 

 famous " Black Thursday " in Melbourne, Dunedin and 

 the southern portion of the south island of New Zealand 

 generally experienced a dense smoke, and comparatively 

 large fragments of carbonised vegetable matter fell. 



In conclusion, I should like to point out the significance 

 of such an observation as this in connection with the dis- 

 tribution of plants in the Southern Hemisphere. Since 

 diatoms and vegetable particles of recognisable size were 

 present in the very small portion of the dust examined, it 

 seems quite possible that in the large total of dust that 

 fell some of the smaller and lighter seeds of Australian^ 

 plants may have been present. 



«« 5:1 ii ! 2.S I g- ! s- ; 3= I Sc 



Sj H c E 5 1 ?.a oj E^ S « ' Bg 



Pate, 1902 or. --a o.fliou J;© 00 *;= ,oS 



caM w'-^- (Ss I «< 1 Q* ; m^ CQ ^gQ 



^^..-.^ j ^ , 



Nov. II 30-08 30 01 I 29'9i 29*95 ~ — I N.W. ; 29 72- 



Nov. 12 30*09 29-96 I 29 78 a9"6i S.E. I 29*9 ' S.W. 23 50 



Nov. 13 ag^** 29'53 1 29'63 3003 W. 29-3 S.W. 2982 



i I , N.W. 10 29-42 



N°^- M 1 2998 29-90 1 30-04 1 30 27 : - - N^E^io ; 



! i I ''•w. - 



Nov. J5 — 30-13 ! 30-14 i 30-18 ; — — i S.W. 12992 



P. Marsh.all. 

 Otago University, Dunedin, New Zealand, Mav 3. 



NO. 1758, VOL. 68] 



Science and Naval Promotion. 



The friends of the advancement of science in the Navy 

 can hardly fail to be very pleased with the recognition it 

 has received in the recent promotions to the rank of com- 

 mander. Of the twenty-seven lieutenants promoted on 

 June 30 last, twenty-one were " specialised officers." In a 

 batch of promotions such as this there is much to encourage 

 our best officers to direct their attention to the more scientific 

 work of their profession, yet one cannot but remark upon 

 a feature in the analysis of these promotions, namely, the 

 marked difference in the average times these new com- 

 manders remained lieutenants. Thus, three lieutenants 

 (T) averaged 10 years ; nine lieutenants (G) averaged 10-5 

 years; nine lieutenants (N) averaged 12-2 years. This is 

 anything but encouraging to the specialist in navigation, 

 but in view of the immense importance of securing the best 

 men to navigate our fleets and handle them in action, it 

 is much to be hoped that in future lieutenants (N) will not 

 be so heavily weighted on their way to the higher ranks of 

 the service. It is, however, only just to add that the theory 

 and practice of navigation under recent legislation have 

 been placed in a position in the front of scientific education 

 they never occupied before. N. G. T. 



Purple Flowers. 

 It is generally thought that purple flowers are due to 

 selection by bees, and the small number of blue and purple 

 flowers in New Zealand is accounted for by the supposed 



