August 8, 1901] 



NA TURE 



i57 



one to Texas and one to eastern Colorado. Word has )ust been 

 received at the Museum that the very first discovery made by 

 the Texas party included a deposit of skulls of the three-toed 

 horse, Protohippus, associated with parts of the limbs, feet and 

 backbone. This is one of the stages especially desired in the 

 long series leading up to the modern horse. The skulls are 

 reported to be the best that have thus far been found, and this 

 discovery is an auspicious opening to this special series of 

 explorations. 



The fifth annual Fungus Foray of the British Mycological 

 Society will be held at Exeter from Monday to Saturday, 

 September 23-28. The club dinner will be held on September 

 24, after which the president, Prof. H. Marshall Ward, F.R.S., 

 will deliver his presidential address. On September 25, Miss 

 A. Lorrain Smith will read a paper on "The Fungi of Germin- 

 ating Farm Seeds," and on the following day a paper on 

 " Spore Formation in Yeasts " will be read by Mr. Barker. 



It has been found that one of the most effective methods for 

 destroying locusts in humid climates is by propagating among 

 them the well-known fungus disease. The Cape of Good Hope 

 fungus, described by Dr. Sinclair Black, is the Empiisa acridii. 

 To employ it, a culture is prepared on moist bread crumbs and 

 scattered in places frequented by the locusts. The locusts which 

 consume the bread die, and their bodies are eaten by other 

 locusts and thus the disease spreads. The method is less 

 effective in dry weather. 



Mr. C. a. Ben bow, writing in the Agrimltiiral Gazette of 

 New South Wales, strongly recommends the introduction of the 

 eland of Cape Colony into the scrub lands of New South Wales 

 and Central Australia. This scrub land is almost valueless as 

 pasture, especially in years of drought. The eland is, however, 

 accustomed to feed on the same leguminous shrubs in South 

 Africa which form the scrub of Australian lands. The animal is 

 one of the largest of the antelopes, often equalling an ox in 

 weight, is easily domesticated and produces meat of exception- 

 ally fine quality. 



In the j9«//£Y/« of the American Geographical Society (No. 3, 

 igoi), Mr. R. de C. Ward gives a note on the climate of 

 Mammoth Tank, situated in the southern portion of the Colorado 

 Desert, and one of the most interesting places in the United 

 States from a meteorological point of view. The mean tem- 

 perature of July is 98°'5, and of January 53°'9. The highest 

 temperature recorded was 130°, in August, 1878, and the lowest 

 22°, in December, 1895, giving an absolute range of 108°; 

 temperatures of 100° and over have been recorded in every 

 month of the year except the four winter months, November to 

 February. The mean annual rainfall for twenty-three years is 

 I 81 inches ; the greatest amount in any one year was 5"48 inches, 

 while in the two years 1897 and 1898 there was only a trace. 



An interesting paper was recently submitted to the Royal 

 Academy of Belgium, by Dr. E. Vanderlinden, on the atmo- 

 spheric conditions that accompany fog in that country. The 

 inquiry is based upon an examination of some 200 synoptic 

 charts, the winter and autumn fogs being studied separately 

 from those which occur in summer. The author shows that the 

 winter fogs are mostly connected with anticyclonic conditions, 

 while those of summer occur during periods of shallow or 

 secondary barometric depressions. The winter fogs rarely occur 

 on the western side of an area of high barometric pressure. In 

 reporting to the Academy upon the paper, M. Lancaster points 

 out that most authors who treat of the quesiion of the formation 

 of fog only deal with very local areas, in which temperature 

 plays the principal part, but that this kind of fog should not be 

 confounded with the general phenomenon characteristic of winter 

 fogs, which depend upon the barometric pressure. The most 

 favourable conditions for fog formation are damp air and a tem- 

 NO. 1658, VOL. 64] 



perature a little above freezing point. These conditions 

 generally occur in winter with westerly winds and when the 

 centre of the high-pressure area lies to the south-east of the 

 point of observation, but M. Lancaster points out that the action 

 of temperature alone is not sufficient to explain completely the 

 occurrence of certain types of fog. 



Since the article upon the recent work of the United States 

 Weather Bureau appeared in Nature of May 23 (p. 80), the 

 Report of the Chief of the Bureau on the operations during the 

 year ending June 30, 1900, has been received. In addition to 

 the usual tables containing the results of observations made at 

 Weather Bureau stations in the United States, Mr. E. B. Baldwin 

 gives a detailed account of the meteorological observations made 

 by him in Franz-Josef Land during the second Wellman ex- 

 pedition in 189S-1899. The lowest temperature experienced 

 seems to have been recorded on February i, 1899, when a mini- 

 mum of forty-five degrees below zero Fahrenheit was observed. 

 The means of the maximum and minimum temperatures recorded 

 by the thermograph in the first three months of the year 1899 

 are as follows, in degrees Fahrenheit :— January, max. - lo°'9, 

 min. -24°o; February, max. -5° '4, min. - i9°-4 ; March, 

 max. l6°7, min. -26° 8. Avery complete record of auroral 

 phenomena was kept by Mr. Baldwin, and has been published 

 in the U.S. Monthly Weather Review for March, 1901. 



The representation of electromagnetic phenomena by 

 mechanical models was brought into prominence many years 

 ago by Maxwell's well-known model of a dicycHc system 

 representing the mutual induction of two currents. Prof. 

 Garbasso now sends us a number of papers dealing with the 

 construction of mechanical models representing the discharge 

 of condensers, in particular in the case when the armatures 

 of a condenser are connected by two wires in parallel. The 

 most recent of his papers, dealing with the maximum value of 

 the electrokinetic energy of mutual induction of two currents 

 and its physical interpretation, appears in the Niiovo Cimento 

 for June (5, i.) 



A note on some discontinuous and indeterminate functions 

 by Mr. Charles Kasson Wead in the Bulletin of the Philo- 

 sophical Society of Washington is rather suggestive. The 

 treatment is based on the fact that if u = {x/a)'" , z« = o or 00, 

 according as -t < or > a, so that if N is any positive number 

 greater than unity, N " " = o or I according as -v > or < a. 

 By means of this factor the author shows how it is possible to 

 construct equations representing broken lines or portions of 

 plane areas within or without given plane curves. As physical 

 applications, the author shows how to represent by a single 

 expression the potential of a solid sphere, or the attraction of a 

 spherical shell at points both inside and outside the sphere. 



We have received several papers by Prof. Sommerfeld, 

 dealing with the theory of the diffraction of Rontgen rays. One 

 of these is published in the Zeitschrift fiir Mathematik und 

 Pkysik, xlvi. i, 2, and abstracts are also given in the Physik- 

 alisehe Zeitschrift, ii. The special problem which forms the 

 subject of Prof. Sommerfeld's work is the mathematical investi- 

 gation of the results of the hypothesis put forward by Wiechert 

 and Stokes, according to which Rontgen rays consist in an 

 impulsive disturbance propagated through the ether. The 

 author considers the problem of diffraction past a screen in the 

 form of a half-plane and allied problems, and compares his 

 results with those found by Haga and Wind and others. The 

 single non-periodic impulse may be said to represent one extreme 

 case of ray-propagation, while the purely periodic wave repre- 

 sents the other extreme. While actual Rontgen rays and Hght- 

 rays probably only approximate to these extreme cases, the 

 agreement between Prof. Sommerfeld's conclusions and experi- 

 mental re.sults affords considerable evidence in favour of the 

 above theory of Rontgen rays. 



