June i i, 190S] 



A'^ TURE 



' jo 



He also mentions that such statements as that the drift is 

 proportional to the velocity, and not to its square, as 

 demonstrated by Langley, find their way into print and 

 are allowed to pass unchallenged. That inaccuracies such 

 .IS Mr. Kitchin mentions are far too common in papers on 

 ■leronautical subjects is probably well known, with the 

 result that the problem of flight is being worked out at 

 the cost of a greater number of failures than would be 

 necessary if more mathematical accuracy could be brought 

 to boar on the work. 



In an article on the discharge of electricity through gases 

 in the May number of the Journal de Physique, M. P. 

 \"illard, after a critical examination of the present view 

 that the luminous phenomena are due to ionisation or re- 

 combination, comes to the conclusion that the opposite is 

 the case, ionisation producing darkness rather than light. 

 His own experiments lead him to the further result that 

 the positive Column is not an assemblage of independent 

 particles, but an object of the nature of a vortex filament 

 behaving like a flexible and extensible conductor, only 

 capable of existing in gas ionised to an extent lying betweer 

 certain limits, but within these limits becoming mor( 

 prominent and stable as the current is increased. The an 

 and electric spark, according to M. Villard, are intense 

 discharges in which the positive colunm plays the mosi 

 important role, the negative phenomena having disappeared, 

 while in the vacuum-tube discharge the opposite holds. 



It has been recognised for some time that when an 

 electric discharge passes through a gas the product of the 

 length of the spark into the pressure of the gas at which 

 the spark passes most easily is a quantity characteristic 

 of the particular gas used, and very nearly proportional 

 to the mean free path of the molecules of the gas. Dr. 

 E. Lohr, of Vienna, finds, .further (Sitzungsberichte der 

 Wiener Akademie, 1907, p. 1281), that the above-named 

 product is inversely proportional to the refraction constant 

 II — I of the gas. Since the mean free path is proportional 

 to the viscosity of the gas. Dr. Lohr draws the somewhat 

 startling conclusion that the velocity of propagation of 

 light in a gas is a function of the viscosity of the gas, 

 and is, ceteris paribus, the greater the greater the 

 viscosity. 



So many experimenters are now interested in the 

 accurate measurement of the alternating currents used in 

 wireless telegraphy that it may be worth while to reproduce 

 a portion of a table of relative sensitiveness of some of 

 the best known of the instruments suitable for such 

 work, given by Von Espinosa in the " JaKrbuch der 

 drahtlosen Telegraphic," p. 328: — ■ 



Walt^; neces- 

 sary to give 

 Instrument Resistance sland.^rd 



in ohms deflection 



Hot wire air-thermometer with thin 



copper wire O'S ... 2-5 xio"-- 



Hot wire air-thermometer with thin 



manganin wire 34 



Bolometer with iron wire in air ... i -8 



ti ,, vacuum 2'2 



Thermo-ccupleof iron-eureka(Kon- 



stantan) in vacuum 5-1 



Duddell thermo-galvanometer ... 18 to 100 



The Board of Education is endeavouring to encourage 

 practical work in the geography teaching of schools, and 

 has suggested exercises of various kinds suitable for the 

 pupils themselves to work. These exercises include a daily 

 record of the pressure and temperature of the atmospher" 



NO. 2015, VOL. 78] 



the amount of rainfall, the direction of the wind, and so 

 on. To assist teachers in securing a permanent record of 

 these observations, Messrs. George Philip and Son, Ltd., 

 have published a Meteorological Calendar consisting of 

 fifty-two weeklv sheets, each of which includes suitable 

 barometer, thermometer, and rainfall tables, and a chart 

 for recording wind direction. The calendar costs 2S. net, 

 and the publishers are prepared to supply the sheets in- 

 quantity for the use of pupils. The sheets should prove- 

 useful in schools. 



TiiE volume of '* Extracts from Narrative Reports of 

 Officers of the Survey of India " for the season 1005-6 

 deals, as usual, with a variety of topics. The progress 

 made with the magnetic survey under the immediate direc- 

 tion of Captain R. H. Thomas, R.E., has been slower 

 than in recent years, owing to the greater remoteness of 

 the districts dealt with. It is hoped, however, that by 

 the end of 1908 the " preliminary " survey will have been 

 completed ; by this apparently is meant a survey suflicient 

 to indicate the general magnetic character of India, leaving 

 for the future a detailed survey of any districts that may 

 prove to be specially disturbed or otherwise of exceptional 

 interest. A variety of magnetic information is given in 

 tabular form, including the diurnal variation from selected' 

 " quiet " days for the observatories at Dehra Dun, 

 Barrackpore, Kodaikanal, and Toungoo. As usual, con- 

 siderable space is devoted to the comparison of instru- 

 ments and their various defects. Pendulum observations 

 were made, as previously, under the direction of Major 

 Leno.x Conyngham, R.E. To eliminate so far as possible 

 the disturbing effects of temperature, observations were- 

 never taken, as in previous years, in a tent, but only 

 where a house of some kind was available. Notwithstand- 

 ing all precautions, irregularities still arise which it seems 

 difficult to account for. During the year nine stations had 

 self-recording tide gauges at work. The observations for 

 1905 were reduced by harmonic analysis at Dehra Dun, 

 while full particulars of the observed values during 1904, 

 with values of the tidal constants for 1908, were trans- 

 mitted to the National Physical Laboratory, where the 

 tidal predictor is at work. Particulars are given of the- 

 comparison of observed and predicted tidal results for 

 1905. Levelling operations were carried out by two 

 parties, but call for no special remark. 



The Clarendon Press, Oxford, has published " A Chart 

 of English Speech Sounds, with Key-words and Notes,"' 

 by Mr. Daniel Jones, lecturer in phonetics at University 

 College, London. The pronunciation of the ■ key-words is 

 that usually adopted by educated people in London and the 

 neighbourhood. The price of the chart is 4^. net. 



Messrs. Macmillan and Co., Ltd., have published a 

 third English edition of Prof. 'Wilhelm Ostwald's " Scien- 

 tific Foundations of Analytical Chemistry treated in an 

 Experimental Manner." The work has been translated 

 by Dr. George M'Gowan from the fourth German edition, 

 with further alterations and additions by Prof. Ostwald. 

 The price of the volume is 6s. net. 



A SALE by auction will take place in Berlin on June 20 

 next of scientific and mathematical manuscripts and books 

 of the sixteenth to the eighteenth centuries. We have 

 received a catalogue of the sale from Mr. W. Junk, 

 Berlin W., Kurfurstendamm 201, with whom those persons 

 unable to attend the sale, yet anxious to procure books or 

 manuscripts, should correspond. 



