"-•8 



NATURE 



[August 9, 1894 



Hope, and St. Helena. But even if the latter were the case, 

 to give conviEcing proof of the correctness of his theory, he 

 noold at the same time have to reproduce the observations at 

 points widely distant from these stations. We would like to 

 ask Wilde to turn out the Ascension declinations and inclina- 

 tions, say, from 170C-1834. L. A. Bauer. 

 Friedenaa, bei Berlin, July 21. 



Time-Gauge of Niagara. 



In the summer of 1S90, I had the opportunity of spending 

 some months in Canada, where I devoted what time I had to 

 spare to the later geology of the country. 



The time-gauge of the Niagara Falls struck me, and naturally 

 led to further investigation. 



We are fairly justified in the assumption, from historical 

 sources in Egypt and elsewhere, that no distinguishable change 

 of climate has occurred for, say, four thousand years. Our first 

 knowledge of Britain, nearly two thousand years ago, would 

 indicate that the climate of the south coast was then, at least in 

 summer, a lew degrees higher than now. Restore the con- 

 ditions, reafforest the country lying north, and we should prob- 

 ably find this state of affairs restored. Four thousand years is 

 a good stretch in the mind to seven thousand, so we may 

 safely assume the '"Glacial Epoch" must be put back an 

 indefinite time beyond that. 



Now we find, looking at the superficial geology of the lakes, 

 that Erie must be dissociated from the other four. There is 

 every reason to believe it was a river basin draining by the 

 Wabash and Manmee valleys into the Mississippi. Ontario 

 again in pre-glacial times drained by Syracuse into the Atlantic. 

 Duiing the Ice Age these drainage valleys were blocked, as was 

 possibly the present discharge by the St. Lawrence past 

 Montreal. In post-glacial times, on the retiring of the ice, 

 Ontario stood at a much higher level, and probably discharged 

 over the Niagara ridge into Erie. 



It is well known that an old river channel exists, pass- 

 ing from above Niagara and tending west of Queenstown 

 to Ontario. It has been assumed that flowing out of Erie the 

 channel divided, one branch flowing west, the other east of 

 Queenstown, and that owing to erosion at the extremity, one 

 (the western) became closed, while the other survived as the 

 Niagara. 



If this were the case, there must have been, for a time, two 

 falls over the escarpment near Queenstown, but there is abso- 

 lutely no evidence of there having been a fall at the extremity 

 of the western branch. 



What seems to have happened was that for an indefinite time 

 Ontario discharged westward into Erie, which again drained 

 into the Upper Mississippi. A slight change of level may have 

 occurred, or a local flood have carried away some of the debris 

 closing the ]-ower St. Lawrence, and Ontario found a way of 

 escape to the east. A rapid erosion of the old valley must have 

 occurred with the result of lowering Erie sutficienlly to reverse 

 its outfall, when the river took the lowest channel, and first 

 flowed, as now, over the escarpment. 



The lime-gauge represents then, not the close of the glaciated 

 period, but the epoch when Ontario returned to its pre-glacial 

 dischaige. The intermediate period, when it flowed into Erie, 

 has apparently left only the old western channel as evidence of 

 what may well have been a protracted period. 



Shanghai, June 22. 1 Hos. W. Ki.ngsmilu 



Late Appearance of the Cuckoo. 



On Friday last, July 27, as I was walking along the Sion 

 Vista in Kew Gardens, towards the river, 1 heard, far ofl' to my 

 left, the cry of a cuckoo. There was but ore cry, and that had 

 not the duplication of the first sound which usually marks his 

 later utterances with us. Clearly thouch I had heard it, I 

 might almost have doubted the testimony of my ears if I had 

 not, on turning tuddcnly to the direction from which the sound 

 had coae, sun the bird riic quickly and fly across the river. 



August I. E. HUBIIARD. 



Height of Barometer. 



Can any of your readers refer me to the maximum and 

 minimum oM/A^n/iVo/rr/ heights of the barometer, which have 

 been hitherto recorded r I) m England, (2) in any part of the 



NO. 1293, VOL. 50J 



world ? It would, of course, be necessary to know the height 

 of the place of observation above sea-level in the case of the 

 minimum, at least. Karl Pearson. 



University College, London, August 5. 



Magnetisation of Rock Pinnacles. 



Mr. Hill will be glad to find that systematic observations on 

 the magnetism of rock masses have been taken for the very 

 district he mentions in his letter of July 2S. 



In vol. X., part 2, of the yournal of the Royal Institution of 

 Cornwall, there appears a short paper on " The Magnetism of 

 the Lizard Rocks," by Mr. Thomas Clark. In this he gives 

 not only the results obtained, but his method of procedure. .\ 

 subsequent paper (printed in vol. xi. , part 2, of the Journal), 

 on "The Magnetic Rocks of Cornwall, "gives the results of his 

 experiments, and is accompanied by a map of the county show- 

 ing the position of its magnetic rocks. I understand that Mr. 

 Clark is continuing his research in this direction. 



If similar observations were taken throughout the whole of 

 the country, especially in the neighbourhood of the coast, doubt- 

 less they would yield results of great value to commerce as well 

 as to science. M. M. S. 



If Mr. Hill will refer to Alpine Jourttal, vol. xiii. p. 439, 

 he will find mention of a magnetic peak in the Black Coolins : 

 the mountain bears the name Bidein Druim nau Ramh. 



Eccles, August 5. James Heelis, 



THE BRITISH ASSOCIA TION. 



Oxford, August 8. 

 '"PHE sixty-fourth meeting of the British .'\ssociation, 

 and the fourth which has been held at Oxford, may 

 now be fairly said to have begun. The reception-room 

 was opened at 2 p.m. on Monday last, and at the moment 

 of the opening of the doors there was an unexampled 

 rush to obtain places in the Sheldonian Theatre for the 

 President's address and the evening lectures. The places 

 in the theatre have been filled with extraordinary quick- 

 ness, and it is to be feared that late-comers, who have 

 not availed themselves of the offer of the Local Secretaries 

 to engage seats beforehand by letter, will be disappointed 

 in the places which they obtain. This is an unusual 

 occurrence, and demands some explanation. The 

 Sheldonian Theatre is the largest building now standing 

 in Oxford. The old Corn Exchange was larger, and 

 could have comfortably accommodated the audience 

 which assembled to hear Lord Salisbury on Wednesday 

 night. But unfortunately it is no longer existent. It has 

 been pulled down, with the other civic buildings, to make 

 room for larger successors, which are only half com- 

 pleted, and the Local Committee must regret, without 

 being able to remedy, the circumstance that the only 

 available place of meeting is insufficient for the needs of 

 the Association. 



Lord Salisbury's address is fully reported in another 

 part of this issue. Many of those who know Lord Salis- 

 bury only as a politician and as Minister for Foreign 

 Affairs, will be surprised at the wide range of thought 

 and reading displayed in this address, and more still at 

 the keen critical faculty displayeil in his h.andling of the 

 diverse topics which he passes under review. Possibly 

 the whole of his audience will not entirely agree with his 

 views on current scientific problems, and his conchuhng 

 remarks on the present position of the Darwinian theory 

 offer almost a repetition of the controversy which made 



