February 24, 192 1] 



NATURE 



849 



at a higher degree of exhaustion. The initial rise of 

 current to its maximum is followed by a fall, the 

 rate of which diminishes with time. In the tube at 

 the high gas pressure the final value of current may 

 be less than half the initial value. In the case of the 

 tubes at lower gas pressure the fall is less pronounced, 

 say 3 or 4 per cent. This fall is not attributable 

 merelv to the high temperature of the filament, but 

 is conditional on the thermionic current being per- 

 niilted to flow. 



Linnean Society, February 3. — Dr. A. Smith Wood- 

 ward, president, in the chair.— M. Christy : Wistman's 

 Wood. Wistman's Wood is a small grove of ancient, 

 but exceedingly gnarled and diminutive, oak-trees 

 {Quercus pedunculata) growing out of an extensive 

 pile of huge angular blocks of granite (known as a 

 "clatter") without a particle of visible soil. The 

 wood is almost in the centre of Dartmoor at an eleva- 

 tion of about 1500 ft. It contains about 300 to 400 

 trees, which are overgrown bv masses of moss and 

 lichens. Particulars of the habit and age of the trees 

 are given. — Dr. .Agnes Arber : The leaf-tip.s of certain 

 Monocotyledons. The leaves of Monocotyledons are 

 studied from the point of view of the phyllode theory. 

 In simple monocotyledonous foliage leaves ter- 

 minating in a solid apex, and also in spathe leaves 

 ending in a similar tip, the main part of the leaf is 

 of leaf-sheath nature?, while the apex represents a 

 vestigial petiole. In complex monocotyledonous 

 leaves which are differentiated into sheath, stalk, and 

 "blade," certain cases are known in which the 

 "blade" terminates in a solid apex. It is provi- 

 sionally suggested that such apices represent the un- 

 expanded tip of the petiole.— T. A. Dymes : Seeding 

 and germination of Riisctis aculeatus, Linn., in the 

 south-eastern quarter of England. The berries and 

 seedlings perish by severe frost, although the adult is 

 hardy. Manv seeds fail to germinate because im- 

 mature. Frost kills many seedlings during the first 

 winter. Better results are obtained by sowing, as 

 soon as the seeds are ripe, at a depth of i in. than at 

 a greater depth or in the spring. Survivors in the 

 second season produce an axis some 3 in. long, bear- 

 ing about six phylloclades in the axils of scale-leaves. 

 The radicle perishes and adventitious roots are pro- 

 duced. Duriner the second winter the seedlings are 

 unable to withstand severe frost. There is no re- 

 capitulation of the ancestry by the seedling. 



Aristotelian Society, February 7. — Lord Haldane, 

 vice-president, in the chair. — Prof. R. F. A. Hoernle : 

 A. plea for a phenomenology of meaning. The task 

 of a phenomenology of meaning is to collect and 

 examine all types of empirical situations in which 

 signs function and meaning is present. This is the 

 more necessary as all the higher activities and all 

 control of social organisations depend on the use of 

 signs. Yet current theories are fragm^entary and one- 

 sided. This is .shown bv an examination of the 

 theories of F. C. S. Schiller, B. Russell, Lady Welby, 

 C. S. Peirce, G. F. Stout, A. Meinong, and E. 

 Husserl. A clue to a completer theory may perhaps 

 be found in the distinction between the indicative and 

 the expressive function of signs. We have the pure 

 indicative function when the existence of A enables 

 us to infer the existence (or non-existence) of B. 

 We have the pure e.xpressive function when an agent 

 makes or utters signs. The two functions are 

 curiously interlaced in intersubjective intercourse. The 

 distinction,, however, requires to be tested further by 

 application to various kinds of non-verbal signs, to 

 symbolic actions, and especially to the functions of 

 sounds in music. 



NO. 2678, VOL. 106] 



Cambridge. 

 Philosopliical Society, January 24. — Prof. Seward, 

 president, in the chair.— G. 1. Taylor: (i) Experi- 

 ments with rotating fluids. A summary of results 

 on three subjects connected with the dynamics of 

 rotating fluids was given without proof. The subjects 

 'treated were (a) ditterence between two- and three- 

 dimensional motion, (b) stability of fluid contained 

 between two cylinders, and (c) motion of a sphere in 

 a rotating fluid. Experiments were described, and in 

 the case of (a) and (c) some were shown at the 

 meeting. (2) Tides in the Bristol Channel. It is 

 shown that the Bristol Channel, which contains some 

 of the largest tides in the world, can be represented 

 with considerable accuracy by a channel the breadth 

 and depth of which vary uniformly from the mouth 

 to the head. Calculations oi the effect of such a 

 channel in increasing the tides are shown to agree 

 well with the observed tides in the Bristol Channel. 

 It appears, therefore, from the results obtained that 

 the usual hvdrodynamical theory of tides accounts 

 quantitatively as well as qualitatively for the ab- 

 normally high tides which exist at the head of the 

 Bristol Channel.— F. W. Aston : The deterioration of 

 fabric under the action of light, and its physical 

 explanation. The only serious factor in deterioration 

 of unprotected aeroplane fabric, doped or undoped, 

 when exposed to weather is found to be the action 

 of sunlight. On investigation this action is shown 

 to be relegated to the ultra-violet part of the spec- 

 trum. This deterioration appears to be due to the 

 formation of ozone from the oxygen of the air which 

 acts upon the fibres. This explanation is upheld by 

 the fact that if the fabric is kept in a vacuum or in 

 an atmosphere of hvdrogen the effect is enormously 

 reduced. Normally,' ozone is formed in oxygen only 

 by the action of light of wave-length too .short to 

 occur in sunlight at all, but this difficulty has been 

 removed by Prof. Lindemann, who shows that the 

 high refractive index of the fibres modifies the photo- 

 electric action, increasing the maximum effective 

 wave-length by a factor which brings the value up to 

 that actually determined by experiment. — S. Lees : 

 Note on constant-volume explosion experiments. .An 

 attempt is made to compute the order of the effect of 

 temperature variations in an explosion vessel on the 

 values of the total internal energy measured. The 

 author gives reasons which indicate that the experi- 

 mentally determined values of internal energy so ob- 

 tained ought to be reduced slightly to get the cor- 

 rected values for uniform temperatures. The correc- 

 tion is probably less than i per cent, for air at 

 1600° C. This correction is probably within the limits 

 of experimental error at the present time. — V. Brun : 

 The function \x]. 



MANCHESTER. 



Literary and Pliilosophical Society, November 30. — 

 Sir Henry A. Miers. president, in the chair. — Prof. 

 T. G. B. Osborn : Notes on stone implements from 

 the Cooper's Creek District, South Australia. Most 

 of the specimens were found in May last on old 

 camping-grounds of the Deari tribe during a visit to 

 Killalpannina, on the Barcoo (Cooper's Creek), in the 

 Lake Evre region. It seems probable that knives 

 were manufactured in certain places and the finished 

 articles carried awav. A crude flake struck off at a 

 single blow served as a temporary cutting instrument 

 provided it had a sharp edge, and was then discarded. 

 Scrapers, knives, flakes, hammer-stones, and stones 

 for grinding and crushing food materials were found. 

 The grinding stones were used for grinding small 

 seeds of Eucalyptus microtheca, etc. ; the crushing 

 stones for breaking hard "beans" of " nardoo " 



