584 



NA TURE 



{April 2\, 1887 



it is still sufficiently bright for observation when viewed with our 

 larger telescopes ; and, as far as I am aware, there are no pub- 

 lished ephemerides later than March 27. To remedy this want, 

 I subjoin places calculated from the elements of Dr. Palisa for 

 Greenwich mean midnight for the period during which the moon 

 w ill be absent. 



Sunspots 



In the summary in regard to solar activity in 1886, published 

 in Nature for March 10, p. 445, it is stated that, during the 

 period from October 31 to December 12, "on six days only out 

 of the forty-two could there be discovered on the sun any trace 

 even of a spot, and on those days only one tiny spot could be seen. " 

 As observed in this locality, there were formed, in the midst of 

 the faculas which came into view on November 14, one spot on 

 November 15 and two spots on November 16 ; all having dis- 

 appeared on November 18, when observation again became 

 possible. On December 8 the first of a group of spots which 

 made a complete transit across the sun's surface appeared. On 

 December 9 this group consisted of three spots, which persisted 

 until the 13th at least, gradually increasing in size. A 

 period of sunspot minimum is best adapted in certain regards 

 to the study of the relations of solar outbursts to magnetic and 

 auroral phenomena ; hence precision at such times, in reference 

 to details of the character here indicated, is not unimportant. 



Lyons, N.Y., March 30 M. A. Veeder 



Ozone 



My attention has been drawn to a letter in your issue of 

 January 13 (p. 248), respecting the production of ozonised air for 

 respiration in pulmonary complaints. I beg to inform " W. H." 

 that there is at present no convenient electrical apparatus devised 

 for use in a room, that would electrify the air with sufficient 

 power to be of much service. A simple plan for obtaining ozone 

 in small quantities is to mix very gradually three parts of strong 

 sulphuric acid with two parts of permanganate of potash in a 

 jam-pot, and place the vessel under the bed. Ozone will be 

 given off from this mixture for some weeks. 



I should be glad to hear the experiences of " W. H." 

 inhaling ozonised air "just sensible to the smell," as I am of 

 opinion that this strength of ozone is rather too great. 



Your correspondent is misled in supposing that the. Engadine 

 hotels possess appliances for ozonising the air of corridors, &c. 

 It is only the Maloja Kursaal which has adopted my device for 

 this purpose. The electric current used is taken off from one 

 of the dynamos used for lighting. A short description of the 

 plan is given in the third edition of my " Alpine Winter," p. 84. 



Upper Engadine A. Tucker Wise 



Electrical Discharges in the Doldrums 

 I QUITE agree with the Hon. Ralph Abercromby as to the 

 continuous electrical discharges in the doldrams ; so is there a 

 continuous discharge of rain. I do not, however, agree with 

 him in thinking that the electrical discharges are in any way 

 directly connected with earth-currents. I should say they are 

 due to electrical discharges on the top of the shower clouds, 

 unaccompanied by thunder. It would be interesting to know 

 if travellers in the centres of Africa and South America have 

 observed this phenomenon there. 



DAVin Wilson-Barker 



Green Light at Sunrise and Sunset 



Mr. R. T. Omond, of the Ben Nevis Observatory, in 

 Nature of February 24, p. 391, asks whether the cause of the 



green colour at sunset at sea is the sun shining through the 

 water ? This cannot be the cause, for I have many times 

 observed this colour at sunrise behind the mountains Madonio 

 or Copo Zaferano, which, from the Observatory, appear higher 

 on the sea horizon than the sun's disk. That is to say, the 

 phenomenon occurs when, for the observer, the sun is entirely 

 above the marine horizon, and no part of the disk can shine 

 through the water. A. Ricc5 



Palermo Observatory 



[This is a well known and obvious effect of atmospheric re- 

 fraction. — Ed.] 



A Sparrow chasing Pigeons 



" E. A. C." inquires in Nature of last week (p. 536), whether 

 any of your readers have observed the sparrow chasing pigeons. 

 This habit of the sparrow is very common ; I have myself often 

 observed it, and I apprehend that few who keep pigeons have 

 not frequently seen such attacks. The pugnacity of the sparrow 

 did not appear to me to be the result of any previous quarrel 

 with the pigeon, as I never saw the former attack the latter 

 except on the wing, and always from underneath. 



Chirbury, Beckenham, Kent, April 12 J. JennerWeir 



A Question for Chemists 



Is it known that a mixture of glycerine and permanganate of 

 potassium will take fire spontaneously immediately after being 

 mixed? If so, I should be glad of any reference to the fact. 



Bradford Wm. West 



THE PARIS ASTRONOMICAL CONGRESS 



7'' HE International Congress called together by the 

 French Government to take steps to obtain a 

 photographic chart of the heavens was opened on Satur- 

 day at the Observatory of Paris, and, from the informa- 

 tion which has reached us so far, it would seem that its 

 labours are likely to have a result of the highest import- 

 ance for the science of this and succeeding centuries. 

 The following Directors of Observatories are already in 

 Paris, or are expected : if half of thein really come, there 

 will be such a meeting of astronomers as has rarely been 

 seen : — 



Perry, Stonyhurst 

 Peters, Clinton (U.S.A.) 

 Pujazon, San Fernando 

 Rayet, Bordeaux 

 Russell, Sydney 

 Schoenfeld, Bonn 

 Struve, Pulkowa 

 Tacchini, Rome 

 Thiele, Copenhagen 

 Tr£?pied, Algiers 

 Vogel, Potsdam 

 Weiss, Vienna 



Baillaud, Toulouse Obser- 

 vatory 

 Bakhuyzen, Leiden 

 Beuf, La Plata 

 Christie, Greenwich 

 Cruls, Rio de Janeiro 

 Donner, Helsingfors 

 Uuner, Lund 

 Folie, Brussels 

 Gill, Cape Town 

 Gyldt-n, Stockholm 

 Krueger, Kiel 

 Oom, Lisbon 



Besides these Directors of Observatories, and of course 

 all the astronomical members of the Institute, there are 

 other astronomers, such as Messrs. Common and Roberts 

 from our own country, and Messrs. Lohse (from Germany), 

 Winterhalter (from Washington), and Hasselberg (from 

 Pulkow-a), whose presence is most important. 



The French Government, the Academy of Sciences 

 (with Dr. Janssen as President), and Admiral Mouchez (the 

 Director of the National Observatory of Paris), seem to 

 have done all in their power to facilitate the labours, and 

 even to provide for the comfort, of the various delegates 

 and others representing the various nationalities ; and at 

 the opening ceremony the manner in which the Institute 

 and Government are doing all they can was evidenced 

 by the fact that the address which was delivered by 

 M. Bertrand, the eminent mathematician, on behalf of 



