December i, 192 i] 



NATURE 



453 



Societies and Academies. 

 London. 

 Geological Society, November 9. — Mr. R. D. Oldham, 



•.esident, in the chair. — L. D. Stamp and S. W. 

 Wooldridge : The igneous and associated rocks of Llan- 

 wrtyd (Brecon). Pt. i : Stratigraphi al (L. D. S.). The 



accession of rocks is given ; the fossils from the lower 



orizon include Dicranograptus rectus, Hopkinson, 

 ^lyptograptus teretiusculus, var. siccatus, EUes and 

 Wood, and Climacograptus schdrenbergi, Lapworth ; 

 those from the higher horizon include Dicellograptus 

 sextans. Hall, and var. exilis, EUes and Wood, and 

 Glyptograptus teretiusculus, var. siccatus, EUes and 

 Wood. Both assemblages are characteristic of the 

 Dicranograptus shales of South W^ales. The volcanic 

 rocks of Llanwrtyd are therefore of lowest Bala 

 (Survey classification) and on the same horizon as the 

 upper basic and upper acid series of Cader Idris. 

 The igneous rocks are cut off on the west by a fault, 

 into which an intrusive mass appears to have been 

 forced. Pt. 2 : Petrographical (S. W. W\). The 

 Lower Ashes are an acid series, of which the most 

 characteristic member is a coarse flinty breccia. The 

 spilites show pillow-structure in the upper part, but 

 pass down into massive, finely vesicular rocks. The 

 spilites are locally associated with spilite-breccias, 

 consisting of angular fragments of various rocks and 

 rounded bombs, of all sizes, of spilitic material. The 

 bands of fine ash frequently interbedded with the 

 sediments form dark flintv rocks weathering white. 

 The intrusion is an enstatite-bearing rock of doubtful 

 affinities.— L. D. Stamp : The base of the Devonian, 

 with special reference to the Welsh borderland. The 

 Ludlow Bone-bed forms a natural base : it consists 

 of fish remains, all of which first appear at this 

 horizon, and are genetically connected with higher 

 Devonian faunas ; it passes laterally into a con- 

 glomerate, and thus forms a natural physical base ; 

 it marks a palaeontological and lithological break 

 which can be correlated all over north-western Europe. 

 The fauna of the lower beds (Ludlow Bone-bed, 

 Downton-Castle Sandstone, and Platxschisma Shales") 

 falls into three groups : — (a) Upper Ludlovian marine 

 species which survived the change Of conditions indi- 

 cated by the bone-bed, but gradually died out ; (h) 

 species which flourished for a short time under the 

 changing conditions ; and (c) new forms, chiefly fishes, 

 which persist, or are closely connected with later 

 Devonian forms. It is suggested, from the associa- 

 tion of the early Downtonian fishes with marine in- 

 vertebrates, that the former could live in either salt or 

 brackish water, but gradually became specialised. 



Royal Meteorological Society, November 16. — Mr. 

 R. H. Hooker, president, in the chair. — H. JeJBreys : 

 The dynamics of wind. Winds can be divided into 

 three main groups according as the pressure differ- 

 ences between places at the same level are mainly 

 occupied in producing acceleration relative to the 

 ground, in guiding the wind under the influence of the 

 earth's rotation or in overcoming friction. Thev are 

 called Eulerian, geostrophic, and antitriptic respec- 

 tively. Tropical cyclones and tornadoes are Eulerian, 

 while sill winds of side extent are approximately geo- 

 strophic ; sea and land breezes and mountain and 

 valley winds are mainly antitriptic. Temperature 

 differences will account for the annual pressure varia- 

 tion in Asia, and probably for the permanent winds 

 of Antarctica. In the case of mountain and sea 

 breezes a fundamental part is played by the deviation 

 of the actual average temperature lapse-rate from the 

 adiabatic value. — N. K. Johnson : The behaviour of 

 pilot-balloons at great heightj. Wind-structure in the 

 NO. 2718, VOL. 108] 



upper atmosphere is generally investigated by foUow- 

 ing a pilot-balloon by means of a theodolite, though 

 at a few stations the baUoon is followed by two 

 theodolites situated at the ends of a base-line. Single- 

 theodolite determinations rest fundamentally upon the 

 assumption that the rate of ascent of the balloon is 

 uniform. When a pilot-balloon is observed with two 

 theodolites at the ends of a base-line the actual height 

 of the balloon is calculated from minute to minute, 

 and this method affords a means of testing the 

 accuracy of the single-theodolite method. Experi- 

 ments on the leakage of pilot-balloons are also 

 detailed. It is concluded that the results of single- 

 theodoHte pilot-balloon ascents carried to great 

 heights must be received with great caution. — C. J. P. 

 Cave : The cloud phenomenon of November 29, 1920. 

 On November 29, 1920, a cloud with a sharp-cut edge 

 passed across the east of England, and was observed 

 as far north as Worksop, Nottinghamshire, and as 

 far south as Hawkhurst, Kent. The cloud moved 

 from the west; in front the sky was clear, behind 

 completely overcast. The progress of the front has 

 been mapped from sunshine records and observers' 

 notes, and the upper-air conditions have been inves- 

 tigated. 



Royal Microscopical Society, November 16. — Mr. D. J. 



Scourfield, vice-president, in the chair. — G. Patchin : 

 The micro-examination of metals, with special refer- 

 ence to silver, gold, and the platinum metals. The 

 presence of foreign bodies, the existence of small 

 quantities of metals, metalloids, etc., which may or 

 mav not exert an injurious effect on the material, 

 the constitution of alloys, and the distribution of con- 

 stituents throughout the metallic mass in relation to 

 the micro-examination of metals, were discussed 

 briefly. The presence of platinum and the platinum 

 metals in gold, silver, and gold-silver alloys and the 

 effect of small quantities of these metals on the sur- 

 face appearance of cupellation beads were described. 

 — W. C. Crawley and H. A. Baylis : Mermis parasitic 

 on ants of the genus Lasius. The winged females ot 

 ants of the genus Lasius frequently show structural 

 peculiarities, especially stunted wings and atrophy of 

 the ovarj', which are the result of infection with a 

 Nematode worm. As Nematodes of this family (Mer- 

 mithidae) remain in a larval condition until after 

 emerging from their hosts, complete description of 

 them involves keeping them alive until they attain 

 maturity. This has been done with the form found 

 in Lasius alienus, L. flavus, and L. uiger. No 

 mature males of the worm were obtained ; since the 

 larvae were found to have a precociously-developed 

 male gland, the species is possibly a protandrous her- 

 maphrodite. This view is supported by the observa- 

 tion that oviposition begins before or during the 

 shedding of the last larva! cuticle. — R. L. Frink : The 

 practical value of the microscope in glass manufac- 

 ture. The use of the microscope as a preventive con- 

 trol in selecting raw materials used as constituents of 

 glass batch and refractories and materials for fur- 

 naces and the detection by means of the microscope 

 of the causes of atriae or coids, stones, seeds, blisters, 

 and other defects in glassware were described. The 

 value of supplementing the jwlariscope tests of the 

 annealing of glass by microscopical tests was also 

 urged. 



Linnean Society, November 17. — Dr. A. Smith Wood- 

 ward, president, in the chair. — A. Smith Woodward : 

 .\ newly-discovered human skull from the Rhodesia 

 Broken Hill Exploration Company's mine in N.W. 

 Rhodesia. The skull evidently belonged to an extinct 

 race of cave-men, with a skull much resembling that 



