NATURE 



[May 8, 19 13 



treatment appreciably lengthens the life of the con- 

 sumptive. If the use of tuberculin had the very 

 marked results claimed by some of its supporters we 

 should have anticipated more definite evidence of its 

 effect on mortality." 



A recent memoir bv Capt. R. T. Well-, on dysentery 

 in Haziribagh Central Jail (Scientific Memoirs by 

 Officers n f the Medical and Sanitary Departments of 

 the Government of India, No. 5;) contains a number 

 of important data bearing on the question of the 

 relation of amoebae to the causation of dysentery. 

 From this, as well as from other recent investigations, 

 it is very clear that great care must be taken to 

 distinguish clearly between harmless contamination- 

 amoebae and the pathogenic amoebae which are the 

 true cause of the disease. Contamination-amoeba; can 

 be cultivated from faces, tap-water, and other mate- 

 rials bv planting them on Musgrave's medium; their 

 cysts are air-borne, and readily gain access to faeces 

 or specimens of pus, however carefully collected, or to 

 any material planted on Musgrave's medium contained 

 in Petri dishes. The true dvsenteric amoeba; differ 

 in their microscopic characters from the contamination- 

 amcebae, and thev do not live more than a few hours 

 after discharge from the body, whether transferred 

 to Musgrave's medium or not. The failure to distin- 

 guish between these two types of amceba; has led in 

 many cases to verv erroneous conclusions being 

 drawn. 



To Symons's Meteorological Magazine for April 

 Mr. R. C. Mossman contributes the second of his 

 interesting papers upon Southern Hemisphere 

 seasonal correlations, showing that in the month 

 of Mav a pronounced opposition exists between the 

 barometric pressure at Stykkisholm, Iceland, lat. 

 65 N., and Laurie Island, South Orkneys, lat. 6i° S. 

 The corrected mean pressure at these two places for 

 the month in question, for the years 1902-11, was re- 

 spectively 2991 and 29-32 in. An examination of the 

 barometric data at other places shows that in South 

 America, south of about lat. 47°, the pressure de- 

 partures are in harmony with those at South Orkneys 

 and South Georgia; but data from intertropical and 

 other regions, e.g. the Azores, United States, &c, 

 show indefinite results. The author therefrom con- 

 -ludes " that the dominating factor influencing these 

 Mav pressure variations in the North and South Atlan- 

 tic is to be found in the nolar regions." As to why 

 the striking differences obtain only in the month of 

 Mav no explanation is offered. Some interesting 

 notes are also made relating to the variations of 

 wind circulation accompanying the differences of pres- 

 sure in the extreme South and far North Atlantic. 



The February number of Less (The Forest) contains 

 articles on the influence of forests on the soil, climate, 

 salubrity, &c, questions already much discussed, and 

 on the modifications caused by man in the distribution 

 of birds. Some birds frequent human habitations to 

 build nests on house roofs, or to obtain food, especially 

 in winter. Wading birds have been driven away by 

 the draining of marshes, and the destruction of woods 

 has deprived certain species of their natural nesting- 

 NO. 2271, VOL. 91] 



places, while the fields and meadows which have taken 

 their place have attracted other species. Instances 

 are given of the effect of these changes in Russia. 



During the solar eclipse of April 17, 1912, deter- 

 minations of magnetic declination were made by a 

 number of observers in order to detect any direct 

 action of the eclipse on the magnetic state of the 

 earth. The general verdict was that the effect, if it 

 existed at all, was ven small. Dr. S. Kalinowski, 

 of Warsaw, however, directed attention in the Octo- 

 ber, 1912, number of Terrestrial Magnetism to the 

 decided difference in the declination curves obtained 

 bv him during the eclipse, and at the same hours on 

 the preceding and following days. The normal in- 

 crease in the westerly declination was replaced by a 

 small decrease followed by a rather rapid increase. 

 Dr. Kalinowski pointed out that the same effect was 

 exhibited in a less marked degree in the curves ob- 

 tained at Beuthen, but that the Potsdam curves did 

 not show it. In a letter to the editor of Terrestrial 

 Magnetism, published in the March, 1913, number, 

 Dr. S. van Dijk states that the curves obtained during 

 the eclipse at De Bilt, Holland, show an effect of the 

 same character as that found by Dr. Kalinowski. 



Messrs. Williams and Norgate inform us that in 

 the advertisement of some of the volumes in the 

 Home University Library, announced in last week's 

 issue, "An Introduction to Mathematics" was, 

 through an oversight, attributed to the Hon. B. 

 Russell in place of Mr. A. N. Whitehead, F.R.S. 

 The volume is correctly advertised in the present issue. 



OUR ASTRONOMICAL COLUMN. 



The Spectra of Nova Geminorum. — In the pub- 

 lications of the Allegheny Observatory of the Univer- 

 sity of Pittsburg (vol. iii., No. 3) Mr. F C. Jordan 

 gives a description of eighteen spectrograms of Nova 

 Geminorum (No. 2). The first of the series of photo- 

 graphs w-as secured on March 16, when the bright 

 lines were strongly developed on the plate, and the 

 absorption lines a little less so, and the last on April 

 14, when no absorption lines were detected at all. 

 The author gives tables of the wave-lengths deter- 

 mined, and a series of intensity curves. He mentions 

 the curious fact that with regard to the H and K 

 absorption lines the weighted means of the velocities 

 deduced from them yield a curve which follows to 

 some extent the light variations of the nova, the 

 velocities being positive when the star is brighter and 

 negative when it is fainter. Mr. Jordan suggests that 

 it would be very desirable to examine the velocity 

 determinations from plates secured at other observa- 

 tories, and for this and other points of view he would 

 place all the plates he secured at the disposal of any 

 astronomer or institution that mav decide to under- 

 take such a discussion. 



Another paper of importance in connection with 

 this nova is that printed in the Monthly Notices of 

 the R.A.S. (vol. lxxiii., No. 5, p. 3S0). The authors, 

 Prof. H. F. Newall and Mr. F. J. Stratton, describe 

 a detailed study they have made of the spectrum of the 

 nova on March 15, and they come to the conclusion 

 i hat the absorption lines are for the most part identical 

 with the lines in a Cygni, and to a small percentage 

 in 7 Cvsrni ; or, in other words, the nova spectrum 

 of that date was an enhanced-line spectrum. The 





