June 9, 1910] 



NATURE 



427 



LETTERS TO THE EDITOR. 

 [The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications.] 

 Meteorological Observations during the Passage of the 

 Earth through the Tail of Halley's Comet. 

 I HAVE cursorily examined, the records from ten register- 

 ing balloons sent up from Ditcham Park and Pyrton Hill 

 on May i8, 19, and 20. Nearly all the traces show large 

 fluctuations of temperature ; but such fluctuations have 

 been observed before, and there is nothing that leads me 

 to suppose that the passage of the earth through the tail 

 of the comet, if, indeed, it occurred before 7 a.m. on 

 May 20, had any effect on the temperature of the upper 

 air. Five of the balloons reached 17 km. or more, and all 

 exceeded 13 km. W. H. Dines. 



June 6. 



The quantity of ozone in the atmosphere at great alti- 

 tudes, which for some time has been the subject of an 

 investigation by the writer, was estimated on May 18 

 and 19. It was thought that, in this way, some light 

 might be thrown on the question as to whether any 

 electrical discharges of any magnitude took place in the 

 higher atmosphere during the transit. 



The method of conducting these measurements is 

 described in the Transactions of the Chemical Society 

 (1910, xcvii., 868), and consists in the use of a concen- 

 trated solution of potassium iodide. It has been found in 

 this work that very dilute ozone reacts with potassium 

 iodide to give iodine, potassium hydroxide, and potassium 

 iodate, the relative amounts of each varying with the 

 temperature. This reaction enables a distinction to be 

 made from oxides of nitrogen, which only give free iodine, 

 and from dilute hydrogen peroxide, which gives iodine and 

 potassium hydroxide, but no iodate. 



Three successful experiments were made with the help 

 of the meteorological balloons at about the time of the 

 transit, and the following results were obtajned : — 



.Amount of ozone ner cubic 

 metre air 

 merm. 



05^ (or I pait in about 26 x 10*) 

 0-54 ( „ ,, 2-4x10*) 



o 43 ( ,. ,, 3*ox ID*) 



The above quantities of ozone are not materially different 

 from the amount usually present in the air at these alti- 

 tudes. Thus the average of three measurements made on 

 March 18 corresponds to 0-72 mgrm. ozone per cubic metre 

 air. 



There was also no appreciable change in the quantity 

 of oxides of nitrogen. J. N. Pring. 



Physica' Laboratory, Manchester University, 



Southern, or an allied species), minute larvae, and other 

 living things were to be seen, and at once the question 

 arose. Would the ooze, detritus, alluvium, or disintegrated 

 rock of itself be so special a fertiliser if this teeming life 

 were absent? The ooze is enriched both by the passing of 

 the matter through the bodies of the animals and by the 

 nitrogen from their corpses. 



It seems to me that there is need for careful study 

 of the alluvium of rivers from this point of view. 

 Life has probably much more to do with the soil of 

 the Nile and other rivers than is generally suspected. 

 It would be a profitable thing for students to examine 

 the mud of rivers like the Nile during the different 

 seasons. It would then probably be found that at low 

 water various annelids and other aquatic life-forms were 

 breeding rapidly. The myriads of young would be carried 

 by the flood into the lands which are irrigated by the river, 

 and here they would not only be the food supply for the 

 larger forms of life, but would help to keep the soil from 

 becoming sour, and supply vast stores of nitrogen for the 

 plants. I should be happy to hear from workers in this 

 field, and give any hints which experience has taught me. 



Gt. Malvern. Hilueric Friend. 



On the Preservation of Hailstones and the Investiga- 

 tion of their Microstructure. 

 The investigation of the microstructure of hailstones in 

 I summer having proved very difficult, if not impossible, I 

 I constructed an apparatus (Fig. i) for their preservation 



Ooze and Irrigation. 



,\ges have passed since the cultivator first realised the 

 value of rivers as agents in fertilising the soil. The Nile 

 is the classical illustration, and everyone has learned in 

 early life to think of Egypt as being dependent on the 

 life-giving waters for its fertilit}-. But have the reasons 

 for that ever been sufficiently investigated? Probably the 

 majority of people would say that the waters of the Nile 

 bring down vast quantities of soil and disintegrated rock 

 from the heart of Africa, and this earthy matter, held in 

 suspension or carried down by the river in spate, contains 

 the chemical elements which are essential to the gro\^^h 

 of plants. I believe that is the usually accepted theon.- ; 

 but does it go to the root of things? Others find the secret 

 in the action of bacteria. I grant the point, but do not 

 think it fully accounts for the facts. I have for some 

 years been engaged in the study of our fresh-water annelids 

 and their place in the economy of nature. I had occasion 

 a few days ago to bring home from the banks of one of 

 our Midland rivers some of the ooze from its banks. 

 When I collected it I found some half-dozen specimens 

 of a common fresh-water worm wriggling about in the 

 slimy mass ; but when I came to examine it at leisure, with 

 pocket lens and microscope, I found it to be teeming with 

 life. Vast numbers of tiny annelids (Tubifex templetoni, 



NO. 2 1 19, VOL. S^] 



until winter time. The apparatus consists of three co-axial 

 cylinders ; the inner space is intended for hail ; the middle 

 space for a mixture of ice and cupric sulphate (approxi- 

 mately in the proportion corresponding to eutectics 

 (= — 1.6°); the outer space for ice, forming a sort of guard 

 coat. 



During the summers of 1908 and 1909 I had only once 

 the opportunity of observing a hailstorm ; this was on 

 August 2 15, 1909, when I was at sea near Helsingfors 

 on my way from Aland to St. Petersburg. This hail 

 lasted three to four minutes ; the hailstones were very 

 small (2-3 mm. diameter), but I gathered 200-300 grams 

 of them, and, in order to avoid their freezing together, 

 immersed them in glass boxes with a mixture of nearly 

 equal parts of benzol and toluol, which I presumed to be 

 of a density equal to the density of hailstones, but which 

 proved to be lighter. These hailstones I brought later to 

 Tomsk (Siberia), and in December sent them to the twelfth 

 Congress of Russian Naturalists and Physicians in session 

 at Moscow. These facts demonstrate thoroughly the possi- 

 bility of the preservation and transport of hailstones. Mv 



