422 



NATURE 



[January 25, 1912 



owing to this fact that the rains at that season are so 

 variable and erratic. The present knowledge of th« upper 

 air currents is scanty, and it follows that forecasts of the 

 \vint«'r rains are considerably more tentative than those 

 (i.r the monsoons. On the basis of the history of past 

 years which have shown a general similarity with igii 

 in respect of meteorological statistics during October and 

 November, it is estimated that the geographical . average 

 i{ the rains in question is not likely to be in defect in 

 northern India; an excess is probable in the Punjab and 

 the west of the United Provinces, but there may be a 

 (Iffect in Gujarat and Sind. The amount of snowfall in 

 thf west Himalayas may be expected to be above the 

 normal. 



PouRiNO oil on troubled waters as a proverb is well 

 known. The actual use of oil at sea for preventing waves 

 from breaking is known, but not so universally. Messrs. 

 I.overidge, Ltd., of The Docks, Cardiff, are supplying a 

 "iivenient device for utilising oil economically. This is 

 ouves's automatic " wave subduer." k cylindrical vessel 

 . ontaining a heavy piston is fixed in the ship near the 

 Low, and a little above the water-line. Two narrow pipes 

 p.'iss from the bottom of this through the plating, one on 

 • ithcr side of the stem, and these pipes are normally closed 

 by taps. The vessel is filled with oil, and the piston is 

 raised by a central screw. It is then ready at any moment 

 to drive the oil through one pipe or both when the proper 

 taps are opened. The amount of oil used per hour appears 

 from a letter by a user to have been in his case about half 

 a gallon only. Being only applied at the bow, the oil 

 does not have time to do much to the waves that break 

 over the bows, but, even so, it appears to have a marked 

 effect further aft, that is, when meeting a heavy sea. With 

 a following wind, however, the trail of oil would seem 

 to be much more efficacious, and the great risk of being 

 pooped at such times is no doubt greatly diminished. 



The application of " flashlight " photography to living 

 microscopical organisms is discussed by Mr. Walter Bag- 

 shaw in the Journal of the Royal Microscopical Society 

 for December, 1911, who points out the advantage, especi- 

 ally in photographing pond life, of using living instead of 

 mounted specimens. Mr. Bagshaw has experimented on 

 I.ophohus crystaUinus, caddis flies, water shrimps, &c., 

 though he has not yet succeeded in photographing darting 

 or rapidly moving objects. The " flashlight " powders give 

 a total exposure of one-thirtieth of a second, irrespective 

 of the quantity used. The best instant for exposure was 

 determined by illuminating the object with a faint side- 

 light and observing it through a hand magnifying glass. 

 Should the method be brought into general use, there 

 appears no reason why an apparatus should not be con- 

 structed which would enable the object to be viewed 

 through the microscope and focussed up to the instant of 

 exposure, as in the reflex camera. The same number of 

 the Journal contains two interesting papers dealing with 

 the optical resolution of minute structures, one by Mr. 

 T. W. Butcher on the structural details of Coscinodiscus 

 asteromphalus, the other by Mr. James Strachan on the 

 scales of Thermobia domestica, an ally of the well-known 

 I.episma saccharina. 



The first number has been received of the Journal of the 

 .Association of Teachers of Mathematics for the South- 

 eastern Part of England, which is to be published three 

 times a year. It contains the presidential address delivered 

 at the inaugural meeting at Tonbridge on November 24, 

 1911, by Dr. A. N. Whitehead. F.R.S., on "The Place of 



NO. 2204, VOL. 88] 



Mathematics in a Liberal Kducation." The new aMOcia- 

 tion consists of nearly fifty members, more than half ■ f 

 whom are women engaged in school tearhin^ 

 district in question, the secretary being Mr. (• 

 Carson. It is intended to promote common action atid 

 unity of purpose among school teachers of all grade>-, 

 including those only engaged in teaching arithmetic. The 

 question may lie asked, why is it not affiliated to the 

 Mathematical .Association? Mr. Carson, however, points 

 out that England is almost alone in preserving an un- 

 natural separation between the professed mathematician 

 and the teacher of elementary mathematics, and he hopes 

 the association may help towards bridging this chasm. 

 In Dr. Whitehead's address we note several interesting 

 suggestions, in particular he emphasises the view that 

 modern education should be based more on a study of 

 modern civilisation and less on that of the civilisation of 

 the Greeks and Romans. In order to effect this object 

 Dr. Whitehead would include in elementary mathematics 

 exercises based on the statistics of modern commerce and 

 politics. If this proposal should do anything to convince 

 a future generation that modern politics ought to be 

 treated as a science and made the subject of qualifying 

 tests similar to thpse required for admission to learn-'l 

 professions, a useful purpose would be served. 



According to a reprint from the November (1911) 

 number of the Proceedings of the .American Academy of 

 .Arts and Sciences, Mr. E. L. Chaffee, of the Jefferson 

 Physical Lal>oratory of Harvard, has devised a system 

 which produces undamped electrical oscillations of 

 extremely high frequency with greater regularity than any 

 of the systems at present in use in wireless telegraphy or 

 telephony. In principle, the method stands intermediate 

 between the methods of Poulsen and of Wien. .A direct- 

 current generator of 530 volts is connected through variable 

 resistances and inductances, and through the primary coil 

 of a closely coupled oscillation transformer, to the oscilla- 

 tion gap. This consists of two parallel plates of one or 

 two square centimetres area 007 millimetre apart, the 

 anode being of copper or silver and the kathode of 

 aluminium. Both anode and kathode are water or air- 

 cooled, and are surrounded by moist hydrogen at atmo- 

 spheric pressure. The primary of the transformer and the 

 spark-gap are shunted by an air condenser, and another 

 is placed in series with the secondary of the transformer. 

 Both admit of variation to secure syntony. A thorough 

 examination of the secondary oscillations has been made 

 by means of the Braun tube oscillograph. 



So much of the recent work on the properties of 

 electrons depends on Stokes's law of resistance to the 

 motion of a sphere in a viscous fluid, that careful tests of 

 the validity of the law have become essential. .According 

 to a reprint from vol. xxxvi. of the Annalcn der Physik, 

 Prof. Knudsen and Dr. Weber, of the University of Copen- 

 hagen, find the law requires modification for small spheres 

 moving through a gas. especially if the pressure of the gas 

 is low. Their method depends on the observation of the 

 logarithmic decrement of the torsional oscillations of a 

 light rod 16 centimetres long with or without light glass 

 spheres of a few millimetres diameter at its ends. The 

 oscillating system was placed in an enclosure which could 

 be evacuated, and observations were taken in air at 

 pressures from 014 to i million dynes per square centi- 

 metre. The resistance to a sphere of radius r moving with 

 velocity v through a gas of viscosity ij is equal to 

 6ir7j;-' ( I + 0-68/+ 0-35/^-1"^^ % 



