Sept. iS. 1879] 



NATURE 



485 



and the character of the cave-deposits ascertained by so com- 

 petent an observer as Mr. Everett. The evidence obtained, 

 though negative, is not without value, and those who are 

 specially interested in cave-explorations, and who have so 

 liberally assisted in the present instance, cannot be reproached 

 with not having availed themselves of the opportunity afforded 

 by Mr. Everett's presence, of obtaining farther information as to 

 the contents of the Borneo Caves. 



It may be added that though for the most part the objects 

 secured were unimportant, there were among the cave-deposits 

 a number of shells of land and freshwater moUusca, which have 

 been examined by Col. Godwin-Austen, and have proved to 

 belong to at least 25 genera and 40 species, some of which are 

 apparently new. Mr. Everett has been requested to devote 

 some attention to collecting a larger series of these shells, but 

 owing to the difficulties of postal communication it is possible 

 that the request may arrive too late. 



The Committee propose to communicate Mr. Everett's final 

 report, together with any observations which seem called for on 

 the specimens which are still to arrive, to the Royal Society. 



Underground lVate7-s. — Tlie fifth report was presented of the 

 Committee appointed in 1874 to inquire into the circulation of 

 underground waters, and the extent to which they may be made 

 available for the water supply of towns and districts. The Com- 

 mittee state that, as the objects of the inquiry become more widely 

 known, there is increasing inclination shown by engineers and 

 contractors to impart information, which accrues ixom day to 

 day, and that they consider it desirable to continue their labours 

 until it becomes the duty of some Government department to 

 undertake the charge. They desire to extend their inquiry 

 beyond the Permian, Triassic, and Jurassic rocks to all permeable 

 formations yielding supplies of potable waters. A large amount 

 of valuable information has been collected in the Midlands and in 

 other districts, of works in progress which will be reported on 

 next year. The attention of the Reporter of the Committee 

 <Mr. De Ranee) has been specially directed to ascertaining the 

 areas of pervious rocks, in each of the river basins of England 

 and Wales, and of the areas of impermeable rocks overlying 

 permeable formations, and forming "supra-pervious" areas, 

 together occupying an area of more than 25,000 square miles, 

 and capable of yielding an amount of water far in excess of the 

 quantity required for uianufactm'ing and potable purposes. The 

 impermeable nature of the Severn river-basin is alluded to, and 

 the consequent danger of abstracting a large volume of its waters 

 for Liverpool water supply commented on. 



Report of the Anthropometric Committee. — This Committee had 

 been appointed for the purpose of continuing the collection of 

 observations on the systematic examination of heights, weights, 

 &c., of human beings in the British Empire and the publication 

 of photographs of typical races of the empire. Considerable 

 progress had been made during the past year, and returns, giving 

 the birth-place, origin and sex, age, height and weight, colour 

 of hair and eyes, girth of chest, strength of arm and eyesight, of 

 pupils at Westminster and other schools, London policemen and 

 letter sorters, workmen, rifle volunteers, soldiers and criminals, 

 had been obtained. By this means the Committee were put in 

 lX)ssession of nearly 12, coo original observations on the main 

 question of weight and height in relation to age, in addition to 

 So,coo already collected. The Committee mbmitlcd a series of 

 tables made up from the information contained in the returns. 

 From these it was shown that the London letter sorters were the 

 lowest in height, the average heights between the ages of 20 and 

 35 being 64 to 67 'I inches. The letter sorters were also at the 

 bottom of the weight table, their average weights in lbs. being 

 122'5 to I39'9. The metropolitan police were at the head of 

 both lists; height 69-2 to 715 in., and weight 162-510 1827 

 lbs. Other tables were given, showing that the average height 

 and weight varies with the social position and occupation of the 

 people, and that to obtain the typical proportions of the British 

 race it would be necessary to measure a proportionate number of 

 individuals of each class. Taking the census of 1871, they 

 would find (hat a model community would consist of I4'82 per 

 cent, of the non-labouring class, 47'46 percent, of the labouring 

 class, and 3772 per cent, of the artisan and operative classes. 

 The nearest approach to such a representative population in a 

 limited space would be found in some of the larger county towns, 

 such as York, Derby, or Exeter. The tables demonstrated that 

 the full stature is attained in the professional class at 21 years, 

 and in the artisan class between 25 and 30 years. American 



statistics showed that a slight increase in height takes place up 

 to the 3Sth year. The growth in weight does not cease w itli 

 that of the stature, but continues slowly in both classes up to 

 about the 30th year. The report concluded by referring to 

 similar investigations which are being made in other countnes, 

 and the coincidence of the several inquiries led to the hope that 

 information of great value might in due course be elicited. 



SECTION A— Mathematical and Physical 

 On Secular Changes in the Specific Inductive Capacity of Glass, 

 by J. E. H. Gordon, B.A.— At Christmas, 1877, I made some 

 determinations of the specific inductive capacity of optical glass 

 by a method which has already been fully described both before 

 this section and elsewhere.^ 



At the end of July, 1879, I commenced a repetition of the 

 experiments, using the same slabs of glass, and was surprised to 

 find a large increase in the specific inductive capacity in every 

 case. In some cases the increase was as much as 20 per cent. 

 The following is a table of the results : — 



Specific Inductive Capacity of Optical Glass 



Christmas, July and 



T^ 1., , , „. '^77 August, 1879 



Double extra dense flmt 3'i64 3'838 



Extra dense flint 3"053 3'52i 



ygll'"'»t 3-013 "'. Z 3-443 



Hard crown 3-108 3-310 



The arrangement of the apparatus, including the coil and 

 rapid break, was precisely the same as in my earlier experiments. 

 The electromotive force was as nearly as possible the same, and 

 experiment has shown that moderate variations in it do not affect 

 the results. 



The differences observed might have been caused by any one 

 of three things : — 



1. By error in the 1879 experiments. 



2. By error in the 1877 experiments. 



3. By a change in the specific inductive capacity of the glass 

 between Christmas 1877 and July 1879. 



[The author, after showing reason for the rejection of (i) 

 and (2) is led to the conclusion that in the course of a year 

 and a half an actual change has taken place in the glasses, 

 which is shown by a considerable real increase in their specific 

 inductive capacities.] To complete our knowledge of this new 

 phenomenon we require a series of monthly observations, ex- 

 tended over perhaps a period of several years. I shall hope to 

 be able to give the results of another year's experiments at the 

 next meeting of the Association. 



These experiments have some importance as regards Prof. 

 Clerk-Maxwell's electro-magnetic theory of light. In a recent 

 lecture i' I ventured to suggest "that it is quite possible that the 

 relation betu een electric induction and light exists — namely, that 

 they are disturbances of the same ether, but that there is some 

 unknown disturbing cause affecting the electric induction." 



Possibly a clue to the nature of this disturbing cause may be 

 found in the fact, that the specific inductive capacities are 

 affected by some of the changes which chemists tell us are 

 constantly going on in glasses, but that these changes do not 

 affect the refractive indices. 



SECTION B— Chemical Science 

 Mr. W. Chandler Roberts, F.R.S., Chemist of the Mint, read 

 a paper On some Experiments with the Induction Balance.— Ha 

 stated that the instrument, which we owe to Prof. Hughes, the 

 discoverer of the microphone, apjieared to be one of no ordinary 

 importance, and although the experiments about to be described 

 were far from complete, they possessed sufficient interest to 

 warrant their being submitted to the Section. He then described 

 and exhibited Prof. Hughes's instrument, showing the extreme 

 delicacy by which changes in the induced current were indicated 

 by the microphone and telephone. 



The relative values of different metals, as indicated by the 

 induction balance, do not accord with the values usually accepted 

 as representing the relative conductivities of the respective metals, 

 and this being the case, Mr. Roberts had ascertained what rela- 



' '^'^".tt Brit. Assoc, 1878; I'roc. Roy. Sac, 191. 1878; Phil. Tram., 

 1879; Four Lectures on Electric Induction," delivered at the Koynl 



Institution (Sampson Low and Co., 1879.) 

 " Koyal Institution, February 6, 1879. 



