14 



NA TURE 



[November 2, 1899 



on the subject of the "November Meteors." A popular 

 interest in, and practical study of, various branches of science is 

 encouraged by the Society, and it is to be hoped that residents 

 of Hampstead are actively supporting its efforts. 



The new session of the Royal Geographical Society will 

 coinmence on Monday, November 13, when the president, Sir 

 Clements Markham, will give a short opening address, to be 

 followed by a paper by Mr. W. Rickmer Rickmers on his 

 "Travels in Bokhara." The paper at the following meeting, 

 November 27, will be by Mr. Vaughan Cornish on " Desert 

 Sand Dunes." At the December meeting, Colonel Sir John 

 Farquharson will probably give an " Account of the Past 

 Twelve Years' Work of the Ordnance Survey," from the 

 directorship of which he has recently retired. Other papers 

 expected to be given during the session are: "An Ascent of 

 Mount Kenya," by Mr. H. J. Mackinder ; " The Work of the 

 Yermak Ice-Breaker in the Spitsbergen Seas," by Admiral 

 •Makarofif; "Travels in Central Asia," by Captain H. H. P. 

 Deasy; "Travels in the Region of Lake Rudolf and the Sobat 

 River," by Captain Wellby ; "Travels in Abyssinia," by Mr. H. 

 Weld Blundell ; and " Anthropogeography of British New 

 Guinea," by Prof. Haddon. 



The Journal of the Society of Arts states that artificial 

 paving stones are being successfully produced in Germany. 

 The demand in all larger cities is said to be so good, and the 

 expense attached to their production under former methods is 

 so large, that any improvements on the older systems, whethe^ 

 in saving!money or in producing a better stone, will be^welcomed 

 by almost all countries. The newest process in Germany is to 

 mix coal-tar with sulphur and warm thoroughly ; to the result- 

 ing semi-liquid mass chlorate of lime is added. After cooling, 

 the mass is broken into small pieces, and mixed with glass or 

 blast-furnace glass slag. This powder is then subjected to a 

 pressure of 200 atmospheres, and reduced to the form or forms 

 wanted. The resistance to wear and tear in use is fully half 

 as great as that of Swedish granite. Thus it commends itself 

 through durability equal to that of many stone roads, resistance 

 to changes of temperature, roughness of surface — giving horses 

 a good foothold — and, finally, non-transmission of sound. In- 

 asmuch as the joinings are very small, dirt is avoided, and 

 - cleaning is very easy. 



The Institution of Mechanical Engineers commenced a series 

 of monthly meetings on Friday last, when a paper was read by 

 Mr. W. Ingham on the incrustation of iron pipes at the Torquay 

 water ^fek^- The water supply is obtained from a tributary of 

 the Riv^ Teign, which rises in the granite hills on a western 

 spur of Dartmoor. The water is conveyed by two cast-iron 

 mains to Torquay, one of them, laid in 1858, ten inches in 

 diameter. At the time the pipes were laid, no one thought 

 that the pure water from the Dartmoor hills would cause much 

 deleterious action upon them. It was, therefore, with consider- 

 able surprise that at the end of eight years the delivering power 

 of the mains was fouiid to be reduced to 51 percent, of their 

 full discharging capacity. A scraper was designed, several years 

 ago, to clean the pipes, and it is now regularly used. The 

 scraper is pushed forward by the pressure of water acting upon 

 pistons a little less in diameter than the diameter of the pipe. 

 As it moves, the knives press outwards against the inside of the 

 pipe and remove projecting nodules. The movement of the 

 scraper through the pipes can be easily followed, when the 

 mains are about three feet deep, by the rumbling noise it 

 ■ makes. The speed varies, of course, and is on the average about 

 2^ miles per hour, but a speed of as much as 7^ miles per hour 

 can be obtained for about three-quarters of a mile on one part of 

 the line. After scraping in 1898, the delivery was increased 

 NO. 1566, VOL. 61] 



from 586 to 708 gallons per minute, and similar results have 

 been recorded for many years. 



Water engineers have to give very serious consideration to 

 the subject of incrustations upon their mains. The deposit 

 varies, of course, according to the nature of the water conveyed. 

 When the water is derived from wells sunk in the chalk, the 

 coating on the pipes is of pure calcium carbonate, which forms a 

 desirable interior surface from one point of view, if not from the 

 other of reduction of pipe area. Mr. W. Ingham states in his 

 paper to the Institution of Mechanical Engineers that, speaking 

 generally, it may be laid down with a fair approximation to the 

 truth that well waters have not as great an action on pipes as 

 those from upland gathering grounds, but 'where the water is 

 soft the corrosive action will be greater. Filtered water has 

 also a less corrosive power than unfiltered water. Whatever 

 protective covering is applied to pipes, soft waters will cause 

 rusting within a few years of being laid. At Torquay six years 

 is the outside limit when this commences, so every precaution is 

 taken to see that the pipes are well coated. Mr. Inghan> 

 remarks that though much has been done to get a satisfactory 

 coating to pipes, there is still considerable room for improve- 

 ment, and it is hardly necessary to point out that a fortune 

 awaits the man who can invent something that will withstand 

 the action of soft waters. 



There seems to be some doubt as to the genuineness of a 

 photograph which has been exhibited at the Royal Photo- 

 graphic Society (picture No. 357), as we gather from a letter 

 published by Lieut. -General Tennant (772^ British Journal oj 

 Pholography, October 13). Although the writer of this note 

 has not seen the said picture, and therefore cannot describe it. 

 General Tennant refers to it as " a very fine picture of clouds, 

 but I am at a loss to understand how it can have been put for- 

 ward as being like an eclipse of the sun." He states further that 

 "high in the sky there appears a bright disc partly hiding a 

 dark one surrounded by a bright halo ... it is as though the 

 bright sun were passing in front of the dark surface of the 

 moon." General Tennant, at the time of writing his letter, 

 stated that he was quite certain that it did not represent any 

 phase of a solar eclipse either at Quetta (the place where the 

 photograph was taken) or elsewhere ; but in a more recent com- 

 munication to the same journal (October 20) he is led to alter 

 his opinion after seeing a photograph of the sun passing behind 

 a church spire, saying that the,,^|^uliaAippearance may possibly 

 be the result of reversion. The latter opinion of General 

 Tennant is no doubt the correct explanation of the abnormal 

 appearance of the photograph in question, but the photographer 

 of picture No. 357 may be glad to learn that a similar photo- 

 graph was obtained at Sir Norman Lockyer's camp at Viziadrug, 

 India, during the same eclipse. The camera used was a folding 

 kodak, taking pictures 5 by 4 inches, and the exposures, four 

 in all, were made by a blue-jacket. Each exposure lasted 

 fifteen seconds, but, during the last, totality ended before the 

 given time of exposure was concluded. This photograph shows 

 the small crescent of the sun that appeared from behind the 

 moon as black, while the disc of the moon is not black (as it 

 appeared in the other three photographs), but nearly white, the 

 density being just sufficient to differentiate between the corona 

 and the moon's limb. This photograph is seemingly the same 

 as No. 357, mentioned above, and its peculiarity is due, without 

 doubt, to a reversal caused by the extreme brilliance of the un- 

 covered portion of the sun. 



The photographic process of preparing textile designs, in- 

 vented by Mr. Jan Szczepanik, was referred to by Prof. R. 

 Beaumont in his opening address at the Yorkshire College, and 

 is described in Pearson's Magazine. Prof, Beaumont has per- 

 sonally examirled the invention, and has seen designs worked 



