398 



NA TURE 



[March 23, 1922 



The resulting reduction in the thermionic current 

 is used to indicate the field strength. — E. B. Ludlam : 

 An attempt to separate the isotopes of chlorine. 

 Hydrogen chloride at a pressure of about two centi- 

 metres of mercury was passed over (a) a water 

 surface, (6) ammonia gas, so that a small fraction 

 was retained uncombined. The chlorine was weighed 

 as silver chloride. Any increase in weight could be 

 attributed to experimental error. — M. H. Belz : 

 The measurement of magnetic susceptibilities at 

 high frequencies. A heterodyne beat method is 

 described, in which changes in inductance are pro- 

 duced by insertion of the specimen inside one of the 

 oscillating coils. Susceptibility is calculated from 

 the change of beat note. The range of frequency 

 employed was 3x10^ to 4x10* per second, and the 

 results show that, up to this point, frequency has no 

 effect. — G. H. Henderson : Note on an attempt to 

 influence the random direction of a particle emission. 

 On applying a magnetic field to radium emanation 

 no change could be detected in the ionization due to 

 beams of a rays parallel and perpendicular to the 

 field. — J. E. P. Wagstaff : Determination of the 

 coefficient of rigidity on a thin glass beam . 



Dublin. 

 Royal Dublin Society, February 28. — Dr. J. A. 

 Scott in the chair. — J. Joly : A new method of 

 finding the discharge of rivers. This is a modifica- 

 tion of the method of chemical hydrometry. A 

 small quantity of uraninite in solution and diluted 

 to a suitable volume is suppUed into the river at a 

 uniform rate for a period of 15 or 20 minutes. At 

 a point lower in the river samples of water are taken. 

 These, after a suitable interval, are examined for 

 radium emanation. A river of 10* litres per second 

 would require about 300 grams of pitchblende for 

 a measurement aiming at an accuracy of one per 

 cent. Ordinary chemical hydrometry would be much 

 more costly and troublesome. — J. G. Rhynehart : 

 On the life-history and bionomics of the flax flea- 

 beetle {Lon^itarsus parvulus, Payk.), with descriptions 

 of the hitherto unknown larval and pupal stages. 

 This flea-beetle is a serious flax pest in Ireland. 

 The adults feed on the leaves of the flax seedlings 

 in May and early June and often destroy large areas. 

 From eggs laid in the soil by over- wintered females 

 are hatched minute larvs; which burrow into and 

 feed upon the roots of the flax plants. Pupation 

 occurs in the soil after about a month of larval life, 

 and a new brood of beetles emerges during the last 

 week of July and the first week of August. Various 

 suggestions for controlUng the pest were discussed, 

 and the results of field experiments point to the fact 

 that Bordeaux mixture tends to repel attacks. — 

 E. J. Sheehy : The influence of feeding on milk fat. 

 An investigation into the effect of increasing or 

 decreasing the ration of three experimental goats 

 indicated that the percentage of butter fat in milk 

 may be increased to a maximum figure, or may be 

 decreased, according to the mode of feeding. Fat, 

 starch, or protein, when added to a poor ration, may 

 raise the percentage of butter fat. — L. B. Smyth: 

 On a variety of Finite occurring at Ballycorus, Co. 

 Dublin. A mineral occurring at the edge of the 

 Leinster Granite is shown to be a hitherto undescribed 

 variety of Finite. 



Edinburgh. 

 Royal Society, March 6, 1922. — Prof. F. O. Bower, 

 president, in the chair. — Prof. J. G. Gray and Capt. 

 J . Gray : Solutions of the problem of the vertical 

 on moving vehicles with special reference to aircraft : 

 — ^The Gray Gyroscopic Stabilisers. Prof. J. G. Gray 

 communicated this paper on the action of various 



NO. 2734, VOL. 109] 



forms of the Gray Stabiliser, an instrument which 

 was brought to the notice of the British Govern- 

 ment early in 191 5, and was adopted by the Royal 

 Naval Air Service in 191 7, and in 1918 received the 

 approval of the Research Council of America. In 

 1 91 8 Prof. Gray was invited by the American Govern- 

 ment to visit America with a view to developing the 

 instruments to the utmost for use in the American 

 Aerial Services. Unfortunately, for reasons which 

 cannot now be given, the instruments were not used 

 by the British Services over the German Unes. The 

 Gray stabiliser does not aim at stabilising an aeroplane 

 as a whole, but provides means whereby instruments 

 of precision used on aircraft, such as horizon mirrors, 

 bombsights, navigational sights, cameras, etc., may 

 be stabilised with respect to the vertical and the 

 horizontal, against both pitching and rolling motions 

 of the aeroplane or airship. This stabiliser finds and 

 maintains the true vertical (the direction assumed 

 by the thread of a simple pendulum as set up in a 

 room) with the utmost exactness on an aeroplane, 

 and is thus available for trimming the aeroplane 

 during cloud flying. The instrument consists of a 

 main stabilising gyroscope, or gyroscopes, attached 

 to the aeroplane by means of a gimbal frame and 

 two sets of pivots. The instrument to be stabilised 

 forms part of the pivoted system. Also forming 

 part of this system is an erector consisting of a member 

 which rotates slowly, on a vertical spindle, in the 

 direction of spin of the main gyroscope, or gyroscopes. 

 This member is provided with a set of compartments, 

 each of which contains a soUd spherical steel ball. 

 The compartments are so shaped that, when the 

 pivoted system is inclined to the vertical, the balls 

 automatically arrange themselves so that the device 

 is erected into the vertical by gyroscopic action, 

 when the balls then automatically arrange themselves 

 as a balanced system. An explanation was given 

 of the various forms of erectors which had been 

 devised ; and it was shown how in each case the 

 device was given a sense, so to speak, of the true 

 vertical, but was rendered blind to the apparent 

 vertical during curved flight. A bombing aeroplane, 

 just previous to running up to a target, executes a 

 rapid turning movement. The Gray stabiliser per- 

 mits of all such manoeuvres being carried out without 

 the introduction of errors. The pioneer instruments, 

 as tested on aeroplanes by R.N.A.S. officers in 1917, 

 using sun-shadow methods of testing, methods which 

 permitted of the accuracy of the instrument being 

 ascertained beyond dispute, were found to have an 

 accuracy of ^^ih. of a degree, or for bombing purposes 

 an accuracy of about 25 feet on the ground from 

 a height of 15,000 feet. The instruments were 

 absolutely undisturbed by pitching and rolUng motions 

 of the aeroplane, even when the flying was carried 

 out with the aeroplane side -on to half a gale of wind. 

 The authors of the paper had been working continu- 

 ously with a view to perfecting these gyroscopic 

 inventions and were in a position to construct 

 stabilisers, for use on aeroplanes and battleships, 

 which would yield for navigational purposes, and for 

 purposes of bombing and gunnery, an accuracy of 

 one or two minutes of angle at the outside. Gray 

 stabiUsers for use with cameras are being constructed 

 for use in the U.S.A. In conclusion Prof. Gray 

 expressed his thanks to the War Committee of the 

 Royal Society of Edinburgh, which in 1915 encouraged 

 his researches in every possible way. — H. W. Brole- 

 mann : Myriapods collected in Mesopotamia and 

 N.-W. Persia by W. Edgar Evans, B.Sc, late Capt. 

 R.A.M.C. Seventeen species — twelve Chilopoda 

 (centipedes) and five Diplopoda (milUpedes) — mostly 

 collected around Amara on Tigris and Ruz, N.-E. of 

 Baghdad, are recorded. Five species and three 



