7 line 7, 1877] 



NATURE 



109 



A priori, the more highly finished should succeed the ruder 

 implements, although of course many cases of their being mixed 

 together were on record. Into the other avenues of discussion 

 he would forbear to enter. 



Prof. Hughes, in reply, said that he wished the subject had 

 been divided, so that they might have considered separately the 

 diflTerent parts of the evidence and the difiercnt sources of error 

 which had still to be eliminated. For instance, he thought it 

 would be very well if they could have an exhibition of, and dis- 

 cussion on, the various ways in which nature breaks, cuts, and 

 otherwise ni-,iks bone and stone as well as of various ruder forms 

 known to be the result of human agency, so as to get clearer 

 ideas as to what might really be taken as evidence of design. He 

 pointed out that the measure of the antiquity of the deposits con- 

 taining the remains of man depended chiefly upon the time it 

 would take to bring about certain geographical changes, either 

 assuming that surrounding conditions hacl practically remained 

 the sa'ne, or allowing for such differences as must have occurred, 

 and of which we can estimate the effect. Applying thi-', while 

 he agreed with Col. Lane Fox's remarks on the slow rate of 

 waste < f the Thames valley, he felt that we must make a very 

 considerable allowance far the probability that during the period 

 from the bronze age to our own man had interfered far more 

 with the free course of the river than during all previous time. 

 Nature might also entirely change the rate of w.iste in such a 

 case by a gentle upheaval or depression causing the more rapid 

 or slower cutting back of the stream. With regard to the exist- 

 ence ol depressions in nnn-calcareoui strata he thought we could 

 detect two ways in which they were formed. One by the forcing 

 out of the plastic material all round the mass of gravel or clay 

 thrown on it, and another when the gravel worked down into the 

 puddled surface of a clay, the softer portions of which oozed up 

 between the sinking stones. In all the cases which had come 

 under his observation in which such phenomena occurred above 

 palseolithic beds, the last appeared to be the explanation, as 

 also in most cases where it "as the only evidence for the more 

 southerly extension of glacial phenomena. 



With regard to the Victoria Cave, he thought that the evidence 

 was as yet decidedly pgainst the pre-glacial age of any of the 

 deposits containing even a suspicion of man. He believed that 

 the deposits along the sides and in the side chambers of a lime- 

 stone cave weie frequently newer than those in the main cave, 

 as the carbonated water, being thrown off the clay, must work 

 the sides down. Whalev-'r miglit be the age of the boulder c'ay 

 on the floor at the miuth of t le cave, he believed that the thin 

 layer which occurred in the talu^ ha 1 lalUn out of a pipe of which 

 there v.iere plenty in the limestone above, and that this clayey 

 bank had ponded back the flood-waters and caused the accumu- 

 lation of mud in the talus inside and the formation of the lami- 

 nated clay. 



Mr. Tiddeman' had thought it unnecessary on this occasion to 

 call attent on to geological minutia; at the cave mouth, but as Prof. 

 Hughes had raised the question of theageofthelioulder clay there 

 he was bound to follow him. Prof. Hughes said the boulder clay 

 fell from the cliff at a time long subsequent to the date v/hen 

 the bones were deposited, but in drawing his section he had 

 omitted a very important feature. They had to dig through 

 twenty feet of talus befare they came to the boulder clay, at the 

 back of which was the hyaena Led ; that represented a very con- 

 siderable lapse of time since the boulders were deposited there. 

 If the boulder clay fell at a subsequent period how was it that it 

 was at the base of all the talus and not mixed up with it. If it 

 fell before the talus began to form tt might practically be con- 

 sidered of glac al age. As regards the reindeer in the lower bed, 

 only one very doubiful specimen had been found since he had 

 had charge of the excavations- The chief matter to be considered 

 was whether this fauna which had been found in Europe and in 

 England with human handiwork, occurred at a time which could 

 be correlated with certain great physical events. All the facts 

 which he had noticed seemed to harmonise with the idea that 

 there had been in England two well-marked glacial periods, and 

 these both prior to the much lesser event of the upper boulder 

 clay of Lancashire. For instance, the boulders made into im- 

 plements which Prof. Hughes bad referred to in Pontnewydd 

 Cave, need not have belonged to the latest glaciation of that 

 country. Mr. Tiddeman would not dispute the fact of a 

 fibula making its way down into the e.irth, especially after Prof. 

 RoUeston's experience, but in the Victoria Cave it would have 



^ In the abstract of Mr. Tiddeman's paper, p. 70, line 40, non-gravch 

 should be riicr-^ravcls ; line 44, iJu-it post-glaciat should be there posr- 



great difficulty. If it were soft mud it might have a chance of 

 getting down, but if it were modern other modern things would 

 go down with it unless it had a start. [Prof Rolleston said it 

 was pointed at both ends] Mr. Tiddeman did not think there 

 was a possibility of its working its way down. There were large 

 blocks of stone and beds of stalagmite which had to be blasted 

 in getting down to it. He hoped geologists would bear in mind 

 as new facts cropped up, the suggestion that we had had two 

 glacial periods. 



THE GREENWICH OBSERVATORY REP OR! 



'T'HE Report of the Astronomer-Royal at the annual visitation 

 on Saturday containeil nothing extraordinary with respect to 

 the ordinary work of the Observatory. With reference to ex- 

 traneous work, there are one or two points worthy of notice. 



First, as regards the operations for the transit of Venus, the 

 Astronomer- Royal reports as follows :— 



The computmg staff under Capt. Tupman has by degrees been 

 reduced to two junior computers within the Observatory ; and 

 one or two computers external to the Observatory, who are em- 

 ployed on large groups of systematic calculations, for which 

 they are remunerated by t.ariff The principal part of the calcu- 

 lations remaining at the last report was that applying to the de- 

 termination of the geographical longitudes of fundamental 

 stations. At the moment of my writing, the last of these (the 

 longitude of Observatory Bay, Kerguelcn) is not ab:olutely 

 finished ; but I trust that it will be so before my presentation of 

 this report ; and then I shall be in position to offer the first 

 determination of correction to parallax from eye-observations of 

 the transit. 



The method of determining the geographical longitude of the 

 principal station in each group by vertical transits of the moon 

 has been found very successful at Honolulu and Rodriguez. For 

 stations in high south latitude, horizontal transits are preferable ; 

 for Kerguelen, as I have mentioned, the work is not quite com- 

 pleted. (It will be remembered that the longitude of Mokattam, 

 the principal Egyptian station, was determined by telegraph.) 

 The corrections to the moon's tabular places have been deter- 

 mined with much care from meridional observations at the prin 

 cipal European observatories. 



The differences of longitude, or the relations of clock-times, 

 within the groups of stations, are ascertained. 



These calculations must be followed by the preparation of the 

 factors of errors of various elements. Little progress is made in 

 these ; the work will not be heavy. 



No further advance is made in the photographic reductions. 

 The work is large, but it is simple, and will not be oppressive. 



.Second, as regards the numerical lunar theory : — 



In the algebraical theory an alteration has been made, by the 

 substitution of the equation of radial f irces for the equation of 

 r'/.f viva. Nearly all the numbers had been com]juted, and the 

 additional numerical operation was small. 



The numerical calculations of the factors of symbolical varia- 

 tions are advancing ; and the computations of the perturbing 

 side of the equations, with due attention to the terms requiring 

 extension of decimals, are in progress. 



The numerical errors to which I alluded in the last report are 

 corrected ; and I do not think that any systematic error now 

 remains. 



With the view of preserving, against the ordinary chances of 

 destruction or abandonment, a work which is already one of 

 considerable magnitude, I have prepared and have printed as 

 Appendix to the Greenwich Observations (with additional copies 

 as for a separate work) the ordinary equations of lunar disturb- 

 ance, the novel theory of symbolical variations, and the numerical 

 developments of the quantities on the first side of the eqaations. 

 The last of these will ultimately require some additions for the 

 terms whose magnitude is increased (in algebraical develop- 

 ment). 



The work is perhaps somewliat larger than I anticipated, and 

 the regularity of its progress has been disturbed by very frequent 

 interruptions of my own attention, occasioned chiefly by annoying 

 occupations on the transit of Venus. 1 trust that it will in future 

 go on in a more orderly and more rapid way. 



.Sir George Airy concludes his report with the following general 

 remarks: — 



The suiiject which, I think, must first present itself to ih.e 

 mind of anyone who has traced the history of the observatory is 

 the increase in the number and the fulness of our occtiprtions. 



