J78 



NA 1 URE 



[October lo, 1895 



Russians ; the latter dealing more especially with wind conciilions 

 in high and low barometric pressures. The German Society 

 for the promotion of scientific balloon ascents, under the 

 patronage of the Emperor, will probably obtain important 

 results, and solve several open questions relating to cloud 

 formation, and atmospheric electricity vmder various hygr^mietric 

 conditions of the atmosphere. 



A SUSPENSION for physical instnimcms ircc irom the viliraiions 

 of the laboratory would be an inestimable boon to physicists, 

 especially in crowded cities. At Leyden University, Prof. 

 Einthoven mounted his delicate capillary electrometer on an 

 iron plate floating on mercury. This deWce was exceedingly 

 successful, although somewhat cumbersome and bulky, and he 

 was thus enabled to take a photographic record of the instrument 

 magnified 800 times. Sir d. B. Airy was in the habit of placing 

 his artificial horizon upon a table suspended by caoutchouc bands 

 attached to another table similarly suspended, the arrangement 

 being repeated three times. This, however, was even more 

 cumbersome. Now Herr W. H. Julius, in Wiedemann's 

 Annalen, describes a contrivance which is both simple and 

 effective. It consists of a small circular table suspended by three 

 vertical wires about 6 or 8 feet long, the ends of which form 

 the points of an equilateral triangle. A movable weight is 

 attached to a rod projecting downwards from the centre of the 

 table. It can be clamped in any position, so as to bring the 

 centre of gra%ity of the table and the instrument into the plane 

 of the table itself. .\ny lateral displacement of the upper ends 

 of the wire will start waves down the wires, which will arrive at the 

 table simultaneously, but will only affect it perceptibly when the 

 period of the disturbance coincides with the period of oscillation 

 of the table about the point of suspension. Even then the axis 

 of the table is always strictly vertical. To clamp the oscillations 

 peculiar to the suspension the author attached little vanes, dipping 

 into oil or water, to the table. With a rough preliminary 

 apparatus constructed in this manner, the author succeeded in 

 reducing the \-ibrations to one-tenth of their original amplitude. 



That sedimentation plays an important part in the purifica- 

 tion of water, was shown as long ago as the year 1886 by Dr. 

 Percy Frankland in the case of his Ialx)ratory experiments on the 

 removal of micro-organisms from water. That it is a factor of 

 great importance in the storage of water in reservoirs, was also 

 shown l)y him in his investigations at the London water-works ; 

 but quite recently Dr. H. J. van 't Hofi' has indicated how this 

 now recognised process nf sedimentation may be taken advantage 

 of in the abstraction of tidal water for purposes of water-supply. 

 It appears that the city of Rotterdam derives its water-supply 

 from the river Maas, and that the Company's intake is situated 

 within the tidal area of the river ; the water is, however, only 

 abstracted at particular times, i.e. two hours after high-water 

 has been reached. During this period the river is at rest, and 

 sedimentation can proceed unhindered, and Dr. van 't Iloff' 

 estimates that at Ica.st 50 per cent, of the bacteria present are 

 eliminated during this time of comparative stagnation. Uhlike 

 the city of Hamburg, which before and during the great cholera 

 epidemic abstracted tidal water from the river Eltie, and distri- 

 buted it in it.s raw condition in Rotterdam, the Maas water is 

 submitted to filtration l)efore delivery. In consc<juence, how- 

 ever, of a very large demand on the rcs<iurces of the water- 

 wnrV;,, 'V,. r:i!c '.f fdtration is considerably higher than it should 

 b' iiliincd with the unpleasant circumstance that 



111' .!- refuse by conilucting it into the river, 



would natur. in anticipate a Iwid l)acleri.-il filtrate. 



Dr. van 'l II ' 1, unfortunately, cite any figures for the 



filtrate, but ktates that " the very satisfactory bacteriological 

 resuitt which obtain at the Rotterdam water-works " arc doubtless 

 in great part a consequence of the improvement which takes 



NO. 1354. VOL. 52] 



place in this tidal water through sedimentation, rendering the 

 raw water comparatively easy lo deal with, whilst its microbial 

 contents after the stagnation period average only from 4,000 to 

 10,000 per cubic centimetre, a remarkalily small number for a 

 polluted water. 



Messrs. Olithant, Anderson, anh Ikkkier are about lo 

 issue a new popular science series for children, under the title of 

 " Science Talks to Young Thinkers." The first volume is 

 " Nature's Story-," by Mr. H. Karquhar. 



The last part of "The Natural History of Plants," by 

 Kerner and Oliver, which Messrs. Blackie have for some months 

 been issuing, has just appeared, and the whole of that excellent 

 work can therefore now be obtained in volumes. 



Messrs. Cassei.l and Co. have issued the first pari of a 

 "new and revised edition" of Sir Robert Ball's "Story of the 

 Heavens." We hope that succeeding parts have been brought 

 up to the present state of knowledge, so that the edition will 

 really be a revised one. 



Several years ago it was intimated by a circular that Dr. 

 Buchanan White was engaged in the preparation of a Flora of 

 Perthshire, which he hoped to issue after a brief period of time. 

 Dr. White's death, last December, prevented its issue by himself, 

 but he left it in a state that permits of its immediate publication ; 

 and we are glad to notice the announcement that the book is to 

 be issued on behalf of the Perthshire Society of Natural Science. 

 Prof. Trail, F.R.S., has undertaken to edit it, and to preface it 

 with a sketch of the author's life and scientific work. 



A series of five simply-worded books on wild flowers, by 

 Dr. XL C. Cooke, has been published by Messrs. T. Nelson 

 and Sons. The volumes are entitled " Down the Lane and 

 Back," " Through the Copse," " A Stroll in a Marsh," 

 " .\round a Cornfield," and " Across a Common." Written in 

 an attractive conversational style, and with scanty use of the 

 " hard words" which children, and even those of older growth, 

 always associate with the study of nature, the Ixjoks are well 

 suited to the juvenile public for whom they are intended. 



We are glad to note that the Harveian oration delivered by 

 Dr. Lauder Brunton before the Royal College of Physicians 

 last October, and jirinted in full in these columns at the time, 

 has been published in the form of a hamly volume by Messrs. 

 Macmillan and Co. It will be remembered that the subject of 

 the oration was " Modern Developments of Harvey's Work " ; 

 and those who know how well and fully Dr. Brunton treated 

 his subject, will be gratified at the publication of the oration in 

 a convenient form. The volume is dedicated to Sir J. Russell 

 Reynolds, the President of the Royal College of Physicians. 



We have received the second part of Mr. J. W. Taylor's 

 " Monograph of the Land and Kreshwalcr Mollusca of the 

 British Isles," from Messrs. Taylor Brothers, Leeds, and are 

 pleased to see that the high standard of excellence to which we 

 called attention in our notice of the first part is well sus- 

 tained. The descriptive text is clear, and generally accurate, 

 while the pa|)er, print, and illustrations (coloured and other- 

 wise) are all praiseworthy. The present part pr.ictically com- 

 pletes the consideration of the shell, and the next issue will be 

 devoted to the animal and its orgiinis-ttion. 



The " Zoologisches Adressbuch," which R. Kriedliinder and 

 Sohn, Berlin, have edited and published in connection wilh the 

 Deutsche Zoologische < •escUschaft, will prove of very great 

 assistance to workers in all parts of the world. The voliuiie 

 contains the names and address of zoologists, anatomists, 

 physiologists, and zoo-palrcontologists of all countries. The 

 classification is according to countries, the towns of which are 



M 



