

May ii, 1882] 



NATURE 



47 



well Cliff. These sands and clays form the Ileadon group ; 

 they consist of freshwater strata with bands of limestone and 

 lignite, but including numerous inconstant intercalations of 

 layers containing marine shells, for the most part much dwarfed. 

 The age of the Headon group, as shown by the fossils which it 

 contains, is that of "'the zone of Ctritkium concavum of conti- 

 nental authors. The brackish-water Headon group is succeeded 

 aj Whitecliff Bay by nearly 100 feet of purely marine strata. 

 These marine beds, which had been shown to rest on an eroded 

 surface of the Headon beds, contain the remarkable fauna which 

 had been recognised by many British and foreign geologists as 

 that of the Lower Oligocene. Similar strata with the same 

 fossils are found in the New Forest, at Lyndhurst, Brockenhurst, 

 Roydon, and other points, and there also attain a considerable 

 thickness, It was pointed out that this marine series is quite 

 distinct from the Headon, or zone of Cerithium concavum, with 

 which it had been confounded. The author had been very 

 severely criticised for the views which he had put forward in a 

 former paper as to the manner in which the Brockenhurst series 

 is represented in the section at the west end of the Isle of Wight. 

 There was much difficulty in these variable estuarine beds in 

 correlating the beds seen in Colwell Bay with those exposed in 

 the cliffs of Headon Hill. With several previous authors 

 on the subject, he maintained that the great -erie- of sand- 

 stones and limestones forming W r arden Point and How Ledge are 

 continuous with those exposed in the face of Headon Hill, and, 

 consequently, that the marine beds of Colwell Bay, overlying 

 those lime-tone serie- are younger than the brackish-water lands 

 interslratified with the Ht-ddon beds of Headon Hill. His 

 critic-, however, insisted that these two beds agreed with one 

 another in such a manner that they must be regarded as parts of 

 the same bed, separated by denudation. In opposition to this 

 view, it was pointed out that the Colwell Bay bed is of the most 

 inconstant cha-acter, and long before reaching Headon Hill is 

 seen to be on the point of thinning out and disappearing alto- 

 gether. In conclusion, the author pointed out that his own 

 interpretation of tht succession and correlation of the strata in 

 the Hampshire basin brings them into complete harmony with 

 that which is maintained by the great maj jrity of continental 

 geologists, while that of his critics appeared to be hopelessly 

 irfeconcileable with their views. 



Chemical Society, May 4. — Dr. Gilbert, president, in the 

 chair. — Prof. J. Dewar, F. R.S., delivered a lecture on the 

 recent development of the theory of dissociation. The lec- 

 turer, after referring to the earlier work of Black on " Physical 

 Chemistry," pointed out the origin of the tern dissociation, and 

 the experiments made thereon by Devil e. Troost proved that 

 dissociation is a function of the temperature, that it is indepen- 

 dent of mass, and that the action is revesible; the process 

 resembles in many respects the condensation and volatilisation 

 of a vapour. The experiments in which vapours are conducted 

 along heated porous tubes, only prove that dissociation takes 

 place, but do not tell us the extent of the dissociation. Exact 

 determinations of the partial pressures obtained by heating 

 various substances, as ammoniochloride of silver, vater, &c, to 

 certain temperatures have been made, and thus curves have been 

 drawn, which, by inspection, show the pressure necessary to 

 prevent the decomposition of a substance at any particular tem- 

 perature. Recent investigations have shown that solid sub- 

 stances have a temperature analogous to the " critical point " of 

 gases, above which they cannot exist ; thus, when hydrogen 

 sulphide and water are subjected to great pressure at low tem- 

 peratures, a crystalline hydrate is formed, but above 40° C. this 

 substance cannot be shown to exist, h iw ever great the pressure 

 may be. If a mixture of hydrogen and iodine be heated to 

 about 300° C, so i.e hydriodic acid is formed ; if hydriodic acid 

 be heated to 300° C, free hydrogen and iodine are formed, and 

 the resulting mixture of hydrogen, iodine, and hydriodic acid 

 has in each case 'he same composition. The lecturer then ex- 

 plained the cy. le of Carnot, and showed how a formula 

 could be deduced from it, by which the Ia.ent heat of a che ideal 

 compound a mid be calculated. The importance of the researches 

 of Andrews on the liquefaction of carbon-dioxide \va- in>i,ted 

 upon, and the a alogy of some of the results with the dis-ocia- 

 tion of chemical ■» 'dies pointed out. In conclusion, the author 

 discussed the pro ability of the dissociation of elemems in the 

 sun's atmosphere, and reasoning from a legitimate extension of 

 the known laws of dissociation, inferred that if hydrogen be 

 considered as the elementary form of mailer, the sun's atmo- 

 sphere is m:>st nnfav arable to dissocia'i'in. 



Anthropological Institute, April 25. — Hyde Clarke, vice- 

 president, in the chair. It was announced that Alfred Morrison, 

 F.G.S.. and Frederick Harold had been elected Members of the 

 Institute. — The Chairman referred at some length to the great 

 loss that anthropological science had suffered by the death of 

 Mr. Darwin, an Honorary Member of the Institute ; Prof. 

 Flower, F.R.S., also offered a tribute to Mr. Darwin's memory. 

 Mr. E. H. Man read a second paper on the aboriginal inhabitants 

 of the Andaman Islands. He touched first upon the important 

 subject of language, and pointed out certain peculiarities con- 

 nected with the varying use of several sets of possessive prono- 

 minal adjectives with particular classes of nouns : in expectation 

 at an early date of a paper on the South Andaman language by 

 the president of the Philological Society, this subject was but 

 briefly dealt with by the author, who next proceeded to describe 

 the Andamanese system of adoption and the recognised degrees 

 of affinity, especially as bearing on the question of marriage, 

 bringing to notice at the same time the erroneous opinions 

 hitherto held on this latter point, as also anent their death and 

 burial customs. Numerous superstitions, beliefs, and traditions 

 were related, the latter treating of the account given by the 

 aborigines regarding the Creation, Deluge, and Dispersion. Mr. 

 Man was careful to state that he had taken the precaution to 

 obtain his information from members of distant tribes who had 

 had no opportunity of intercourse with Europeans or other aliens 

 residing at Port Blair, and added that it was extremely im- 

 probable, for the reasons noted in his paper, that any previous 

 generations of these islanders, witbiu historic times, by whom 

 these traditions had been handed down, could have obtained their 

 from strangers. 



Royal Horticultural Society, April 25.— Sir J. D. Hooker, 

 in the chair. — Larches attacked by lai-ue : Mr. Maclachlan 

 reported upon some specimens of larch twigs received from Mr. 

 R. Clutton, of Hartwood, Reigate, who stated that thousands 

 of young larches were attacked by larvae at Box Hill — "the 

 affected trees swarm with little grubs which move about in their 

 cocoons, and seem to suck the juices from the young foliage, 

 leaving it dead, and so kill the trees." They proved to be the 

 larvae of a minute moth, Coleophora laricella, which lays its eggs 

 on the twigs or buds. The larva? hatched in autumn construct 

 cases of cuticle, &c. The young autumn larvae attach their 

 cases to the young leaves in spring, which they soon mine and 

 destroy. Mr. Maclachlan is of opinion that the damage done by 

 this insect is not likely to seriously injure larches. Heremarked 

 that Box Hill being chalk and dry, was not well suited for the 

 growth of larches. — Fertilisation of Hoya : Mr. W. G. Smith 

 referred to this subject, and exhibited flowers with flies attached 

 to the glutinous disks of the pollen-masses. The Hoya is 

 highly fragrant. This fragrance is very attractive to insects, 

 which are necessary for fertilisation of this plant. The pollinia 

 are concealed, excepting the dark viscid disks, which are ex- 

 posed. When an insect alights on the flowers, one foot at least 

 slips and gets caught by one of the fine little glutinous disks. In 

 its effort to escape two, three, or even four other feet are almost 

 sure to get similarly caught. The insect then tries with all its 

 power to free its limbs. If successful the pollen-masses are 

 withdrawn out of the pouches by the feet. The basal 

 appendages of each pair of pollinia are elastic, and when in the 

 pouch they are like an extended spring, but the instant the 

 masses are drawn out, the spring closes, and the two pollen 

 masses quickly cross each other and hold tightly on to the 

 insect's little claws. If the insect is weak, it cannot withdraw 

 its legs at all, and so perishes on the flower ; but if strong, it 

 flies away with one to five pairs of pollinia clasped round its 

 feet. Sometimes an insect breaks part of its leg off in trying to 

 withdraw it. The five stigmas are not ready to receive the 

 pollen at the time the pollen is mature ; so that it is only when 

 the insect realights on some neighbouring Hoya-flower in a 

 more advanced stage of growth that cross-fertilisation takes 

 place by its treading on the exposed stigmas. 



Edinburgh 



Royal Society, May I. — Mr. Milne Home, vice-president, 

 in the chair. — Prof. Piazzi Smyth, Astronomer-Royal for Scot- 

 land, read a paper on some points in the meteorology of Madeira, 

 both absolute and comparative. By a careful comparison of the 

 mean monthly temperatures, the maximum temperatures, and 

 the mean daily range, during the months of June and July at 

 Madeira and Lisbon, it appeared that the temperature at the 



