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SCIENCE-GOSSIP. 



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GEOLOGY 



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MICROSCOPY 



Niagara. — A party of geologists who have been 

 examining the Niagara River, came to the conclusion 

 that the Upper Lakes had probably at one time 

 found an outlet by way of the Mississippi Valley, 

 and that the whole chain might do so again should 

 there ever be a barrier across the inlet of the 

 Niagara near Buffalo. It was thought that a dam 

 25 feet high might bring about this, and cause a 

 grander river than any now on the Continent to 

 flow out from Lake Michigan, near Chicago. 

 Professor Spencer puts Niagara Falls down at 

 about 31,000 years of age, and the Niagara River, 

 ere the formation of the Falls, at 1,000 years older. 

 They formed at one time three cascades instead of, 

 as now, one cataract. 



The subject of the foregoing note from the 

 " Echo,'' referring to Professor Spencer's paper 

 read before the American Association for the 

 Advancement of Science, is a favourite one with 

 geologists. Since quite early in the century many 

 eminent geologists have been endeavouring to gauge 

 with approximate accuracy, the age of the Niagara 

 Falls. It seems to be demonstrated that the Falls 

 date from the glacial period, and consequently in 

 fixing their age, we should at the same time fix the 

 date of the glacial period. Lyell's first estimate 

 of this date, based on the rate of erosion of the 

 Niagara River, was 100,000 years, but when he 

 came into possession of more reliable data, he 

 modified this to 35,000 years, and now the most 

 careful estimates range from 30,000 to 40,000 

 years. 



Geological Maps'. — It is, we think, a great 

 pity that the maps of our Geological Survey 

 are so unnecessarily expensive. Very few firms 

 keep any of them in stock, and those who do, 

 complain that there is no sale for them. The 

 sheets lie in their drawers till they become torn 

 and soiled ; and no wonder, for how many amateur 

 geologists care to spend from three to eight 

 shillings for a map they may only use, perhaps, on 

 a fortnight's holiday ? Yet geological maps of 

 Germany on a scale of two and a half inches to the 

 mile, with contour lines for every ten metres, 

 three sections, and one hundred pages of 

 descriptive letterpress can be sold for two marks. 

 The cause of this great difference in price lies in 

 the fact that the German maps are lithographed, 

 while the English ones are hand-coloured. English 

 lithography is notoriously abominable, while the 

 German workmen turn out artistic masterpieces. 

 But surely some printer in England can be found 

 to colour a map with precision and neatness ! 

 No country in the world can boast of a greater 

 number of hard-w^orking geologists than England, 

 and no country sells fewer maps. It is time the 

 Director of the Survey was approached on the 

 subject, as it is to the interest of science, as well as 

 of all concerned, that the public be supplied with 

 good maps at the least-possib^ expense. 



However pure in appearance, ice may contain 

 disease germs capable of development when taken 

 into the system or brought into contact with food 

 or drink. The evils attributed to the temperature 

 of ice may be due to the germs. 



Mounting Chara. — I should be glad if some 

 correspondent of Science-Gossip would inform 

 me how, having some clean Chara, I can mount it 

 so as to show the manubria of the antheridium and 

 the spore-cells of the oogonium. — J. Leuion Brain, 

 Swanton Morley, East Dereham; Sept. yth, 1894. 



The University of Pennsylvania exhibited a giant 

 Microtone at Chicago, which was used for cutting 

 microscopic sections through the entire brain. 

 The object to be sectioned is fixed at the end of a 

 very heavy lever and allowed to sink down upon 

 the edge of a broad knife, the blade of which is 

 parallel to the side of the lever. The section as it 

 comes off is caught on a sloping sheet of paper. 



In the American Monthly Microscopical Journal, 

 No. 170, a method of making wax models of 

 microscopic objects has been devised. A camera 

 drawing is made of each section in the series. The 

 paper, which is very thin, is then attached to a 

 sheet of wax. For an enlargement of twenty-five, 

 the wax must be twenty-five times as thick as the 

 section just drawn. The edges are trimmed to fit 

 the paper outline, and the successive layers of wax 

 are put together in the same order that the section 

 occupied before being cut. 



Dendritic Crystals. — It may be interesting as 

 an additional note to the controversy about dendritic 

 crystals to say that about twenty years ago I was 

 walking from Sulby to Naseby, Northamptonshire, 

 and on the road-side I saw numerous heaps of flint 

 stones, and on many of these stones I observed 

 beautiful dendritic crystals w-hich at first I took to 

 be some microscopic moss or hepatic, but, on 

 examination at the School of Mines, were found to 

 be dendritic crystals of Manganese.— 7. Rogers, 

 27, Oldham Road, Manchester. 



At a recent meeting of the Dublin Microscopical 

 Society, Professor T. Johnson exhibited a living 

 specimen of Halosphara viridis, a minute globular 

 green Alga, which was found floating at the surface 

 of the sea by the exhibitor when with the fishing- 

 survey boat "Harlequin," in April, 1891, off the 

 coast of Galway. The material exhibited had been 

 sent from Plymouth by Mr. Garstang, who had 

 taken it there in a tow-net for some time past. 

 The life history of the weed is at present 

 incomplete, but it is hoped, by the examination of 

 specimens now under cultivation, to make it known. 

 Halosphcera was first observed at Naples, several 

 vears later at Plymouth, and in 1891 along the 

 south and west coast of Ireland. A source of food 

 supply, and as an oxygenator of the sea-water, it 

 must be regarded as an important economic 

 plankton member. 



