December 27, 1900] 



NATURE 



219 



The method of overstraining and examining the materials 

 employed was analogous to that described in a paper by the 

 present author, "On the Recovery of Iron from Overstrain" 

 (Phil. Trans., A., vol. cxciii. , 1899). 



Experiments described in the paper, of which this is an 

 abstract, showed that with mild steel which had been hardened 

 by tensile overstrain until it could withstand a load of 50 tons 

 per square inch without yielding, no appreciable softening was 

 produced by heating the material to 300° C. A temperature of 

 350° C., however, lowered the yield-point to about 47 tons per 

 square inch ; 500", 600° and 700° C. lowered the yield-point to 

 about 40, 35 and 30 tons per square inch respectively. 



U was further shown that the same temperature brought the 

 yield-point to approximately the same stress, no matter what 

 might be the original hardness of the specimen under test ; and 

 that the harder the material was made by tensile overstrain — 

 that is, the higher the yield-point was raised by permanent 

 stretching — the lower was the temperature which could be shown 

 to produce a slight tempering effect. 



The results ascribed above solely to temperature were found 

 to be influenced to some extent by time. Thus it was found 

 that by baking a hardened specimen for several hours at any 

 temperature a greater effect was produced than by simply raising 

 the specimen for a few minutes to that temperature. The effect 

 of time was, however, small compared with that produced by 

 increase of temperature. 



All the tempering effects observed with steel were also 

 obtamed with Lowmoor iron. The hardening by overstrain and 

 the tempering of soft Lowmoor iron only differed in detail from 

 the analogous hardening and tempering of steel. 



The iron and steel employed in this research were also 

 examined when in various "conditions of hardness by means of 

 the microscope, and micro-photographs are reproduced in the 

 paper. The ordinary methods of relief- polishing and of etching 

 by dilute nitric acid were employed, and a new method of 

 staining steel by rubbing with ordinary moistened cocoa was 

 made use of and is described in the paper. 



Geological Society, December 5.— J. J. H. Teall, 

 F.R.S., President, in the chair. — On the Corallian rocks of St. 

 Ives (Hunts) and Elsworth, by C. B. Wedd. (Communicated 

 by permission of the Director-General of the Geological Survey.) 

 Starting two and a half miles south-west of Elsworth, the 

 author traces the Elsworth rock at intervals through Croxton, 

 Veiling, Papworth Everard, &c., to Elsworth, and thence to- 

 wards Fen Drayton and near Swavesey. The Oxford clay is 

 found to the west of it, and the Ampthill clay to the east. 

 Frequent fossil lists are given, and the character of the rock is 

 described at the different exposures. Again, from Haughton 

 Hall, west of St. Ives, the "St. Ives Rock" is traced through 

 that town and towards Holywell. — The unconformity of the 

 Upper (red) Coal Measures to the Middle (grey) Coal Measures 

 of the Shropshire- coalfields, and its bearing upon the extension 

 of the latter under the Triassic rocks, by W. J. Clarke. The 

 Upper Red Measures have a much greater extension in the 

 Shropshire coalfields than the productive Measures below. In 

 the Shrewsbury field they are the only Carboniferous rocks 

 present, and rest on pre-Carboniferous rocks. When the sec- 

 tions of colleries at and near Madeley are plotted on the assump- 

 tion that the base of the Upper Carboniferous rocks is hori- 

 zontal, the Lower Measures are found to be bent into a syncline 

 rising sharply to the north-north-west and more gently to the 

 south-south-east. A second syncline, broader and deeper, ex- 

 tends from Stirchly towards Hadley, but the westerly rise is 

 often hidden by the boundary-fault of the coalfield. This 

 phenomenon is known locally as the " Symon Fault " ; and 

 instead of taking Scott's view that it represents a hollow 

 denuded in the Lower Coal Measures, the author considers it 

 due to folding before late Carboniferous times. A third little 

 syncline occurs at the Inett and Caughley. Similar phenomena 

 are exhibited in the Forest of Wyre coalfield, where a series of 

 unproductive measures come in between the Lower and Upper 

 Coal Measures. — Bajocian and contiguous deposits in the 

 northern Cotteswolds : the main hill-mass, by S. S. Buckman. 

 After giving comparative sections at Cleeve, Leckhampton Hill, 

 and Birdlip, to show the disappearance of three horizons at the 

 second locality and five more at the third, the author interprets 

 the absence of the beds as due to " pene-contemporaneous 

 erosion " brought about by the elevation of rocks, due to small 

 earth-movements along a main south-west to north-east axis and 

 subsidiary axes north- west to south-east. 



NO. 1626, VOL. 63] 



Entomological Society, December 5. — Mr. G. H. Verrall, 

 President, in the chair. — Mr. Jacoby exhibited specimens of 

 Hypocephalus armatus from Bahia and Chrysomela salisburiensis, 

 a new species, from Mashonaland. — Mr. Bower exhibited a 

 specimen of Spilosoina fiiontanurii, an Asiatic species, bred from 

 a larva found beginning of September 1897, feeding on birch on 

 a moor near Paisley. The larva hibernated and spun a cocoon 

 the following spring, not feeding after hibernation. Moth bred 

 June 2, 1898. The moor on which the larva was found is used 

 by the Glasgow Corporation for rubbish, the supposition being 

 that an ovum or larva had been introduced with the refuse 

 matter. — Mr. McLachlan exhibited a female of a dragon-fly of 

 the genus Tetracanihagyna from North Borneo, similar to T. 

 vittata, McLach., but with a very broad ante-apical fascia on 

 the wings, and with some asymmetrical markings. He said 

 there might be a question as to the specific identity or otherwise 

 of the insect. There was also the question as to whether the 

 insect described by Mr. C. O. Waterhouse as Gynacantha 

 plagiata in the Transactions for 1878 was specifically the same. 

 Mr. Waterhouse was of opinion that his insect was distinct. — 

 Mr. R. Adkin exhibited two aberrant male specimens of 

 Argynnis aglaia. In one of them the basal two-thirds of all the 

 wings were almost completely covered with black, and broad 

 black streaks crossed the remaining third of the wings to the 

 outer margin, following the venation. In the other specimen 

 the peculiarity consisted in the presence of a greenish-white 

 blotch on each of the wings on the left side, similar in character 

 to the pale blotches not infrequently observed in A. paphia. 

 Both specimens were taken near Brighton in July last, where 

 the species was unusually abundant. — Papers were communicated 

 on observations on some species of Orina, a genus of viviparous 

 and ovo-viviparous beetles, by Mr. G. C. Champion and Dr. T. 

 A. Chapman, reported by Dr. T. A. Chapman ; illustrations of 

 the sixth male ventral segment in seventeen species of Osmia of 

 the Adiinca group, with a note on the synonymy of three- 

 species, and descriptions of five which appear to be new, by the 

 Rev. F. D. Morice, M.A. ; and an obituary notice of the late 

 Dr.^Otto Staudinger, by Mr. H. J. Elwes, F.R.S. 



Linnean Society, December 6.— Mr. F. D. Godman,, 

 F.R.S., Vice-President, in the chair. — Dr. A. B. Rendle ex- 

 hibited specimens, including leaves and fruit, of Grasswrack 

 (Zostera marina, L.) recently found by Capt. H. P. Deasy near 

 Yepal Ungar, in the Kwen Lun mountains, at an altitude of 

 16,500 feet. The plants were not growing in this remarkable, 

 locality, but were preserved in a bed 10 to 12 feet thick on 

 top of and interspersed with which were strata of blue clay. . 

 The broken leaves and sheaths of which the specimens consisted: 

 were dry and brittle, but showed no alteration, the internal 

 structure being as perfect as in the fresh plant. As the country 

 is geologically unknown, it is impossible to estimate the age of 

 the deposit. It probably formed the bed of a salt-lake. There, 

 is one in the neighbourhood ; and Capt. Deasy isof opinion that 

 the whole district formed at one time a large salt-lake. The 

 specimens were very dusty, but microscopic examination of the 

 dust revealed nothing beyond particles of sand and a few smalh 

 brown objects, apparently spores of some kind. Capt. Deasy 

 states that he saw similar growths in a lake in the same district, 

 but was unable to procure specimens. This occurrence of 

 Zostera marina in the heart of the Asiatic continent, and at so 

 great an elevation, is of special interest. The plant, so far as. 

 known, is purely marine, occurring plentifully on our own coasts 

 and throughout Europe, on the Atlantic shores of North America, 

 and in North-east Asia, It has not previously been recorded fron^ 

 an inland lake, though an allied species, Zostera nana, L. , occurs- 

 in the Caspian. Whether its existence in the Kwen Lun range- 

 has any relation to the Tertiary marine deposits which connect' 

 the Mediterranean area with the Himalayas is matter for con- 

 jecture. There seems to be some evidence for the existence of 

 Zostera in Upper Cretaceous and Tertiary times ; at any rate 

 several species have been described from fossils resembling the 

 rhizome of the plant, found in Central European beds. Dr. 

 Rendle also showed a specimen of another marine monocotyle- 

 donous plant, Halophila stipulacea, Asch., from Tuticorin in 

 Southern India, sent by Mr. Edgar Thurston. This species is 

 not included in the "Flora of British India," nor in Trimen's 

 " Ceylon Flora," a plant found by Dr. Harvey at Trincomalee, 

 and thus determined by Thwaites, being assigned to the com- 

 moner H. ovata. Gaud. H. stipulacea occurs in the Red Sea, the 

 Mascarene Islands, and Rodriguez. — The Rev. John Gerard ex- 

 hibited some abnormally large shells of the swan mussel, Ano- 



