May 5, 1881] 



NATURE 



17 



each of the departments, and a guide to the whole place costs 

 only threepence. This is as it should be. 



From Gustav Wolf, the Leipzig publisher, we have received 

 a copy of a most useful " Naturwissenschaftlich-mathematisches 

 Vademecum. " The catalogue is really an index, both of subjects 

 and authors, to all recent publications of importance in physical 

 and natural science, and is likely to prove of real service to all 

 scientific workers. 



At the meeting on April 26 of the Institution of Civil 

 Engineers, Mr. Walter R. Browne, M.A., M.Inst. C.E., read 

 a paper on "The Relative Value of Tidal and Upland Waters 

 in maintaining Rivers, Estuaries, and Harbours." The author, 

 while decUning to lay down any universal rule, held as a general 

 principle that the main scouring agent was not the tidal but the 

 lo'.v-water flow. This principle was supported by the following 

 line of argument : — I. The silt, which tended to choke up tidal 

 channels, was almost wholly due to the tidal water, and not to 

 the fresh water. 2. The tidal water brought up more silt on the 

 flow than it took down on the ebb ; i.e., on the whole it tended 

 to choke the channel, not to scour it. 3. The low-water flow, 

 if left to itself, scoured away the deposit and kept the channel 

 open 4. Hence it was concluded that where the two acted 

 together, the scour must be due mainly, if not entu'ely, to the 

 low-water flow, and not to the tidal flow. It was added that 

 low -water scour was in its nature self-regulating, whilst tidal 

 scour, if it once began, would tend to increase indefinitely. 

 But the essential point v\'as to discover the ratio of the bottom 

 to the surface velocity under all possible circumstances, since it 

 was obvious that the former alone had any scoiu-ing effect. 

 Tables were given showing that the ratio of bottom to surface 

 velocity diminished rapidly with an increase of depth ; but their 

 application to tidal channels was doubtful, because then the 

 river, i.istead of being (in a theoretical point of view) inde- 

 finitely long, fell at a short distance into an estuary whose waters 

 might be considered at rest. The author had conducted two 

 series of experiments on the surface and bottom velocities of the 

 River Avon, in the course of an ebb-tide. Both series of 

 experiments showed that during the greater part of the ebb the 

 bottom velocity was actually nil. When about two thirds of 

 the ebb was over, the bottom layers of water appeared to start 

 into activity, and to assume a velocity about two-thirds of that 

 at the surface. This is shown by the following extract from 

 the tables : — 



The following conclusions were drawn from these and other 

 experiments : — In the largest rivers the bottom velocity is for 

 practical purposes the same as the surface velocity. In ordinary 

 rivers the bottom velocity bears to the surface velocity a ratio 

 which is about three-fourths at 5 feet depth, one-half at 15 feet, 

 and one-third at 25 feet. In tidal channels, such as the Avon, 

 during two-thirds of the ebb the slope of the surface is exceed- 

 ingly small ; and while the surface velocity is large the bottom 

 velocity is nil. During this period no scour, but rather deposit, 

 is going on. For the remainder of the ebb the conditions ap- 

 pro.\imate to those of an ordinary river ; scour does go on, but 

 its amount is insufficient to sweep away the silt which has been 

 deposited, not only at the top of the tide, but also during two- 

 thirds of the ebb. Embankments had frequently proved bene- 

 ficial rather than the reverse ; a fact explained by the author's 

 experiments, since the level of the ebb tide would in conse- 



quence fall [more rapidly, and the point at which the water at 

 the bottom began to move would be reached at an earlier 

 period. Again, the process called "dockising," or damming a 

 river at its mouth, had frequently been condemned on account 

 of supposed injury to the river itself, or even to the estuary in 

 which it flowed, but, as would appear from this paper, without 

 foundation. The results would exercise an important influence 

 on other cases, both of theory and practice. 



A SHOCK of earthquake is reported on the night of April 28 

 from Sicily and the province of Reggio di Calabria, and as far 

 as Catanzaro and Monteleone. 



We learn that M. Alphaud, the Director of Public Works in 

 ParLs, has in his hands the tender of Siemens and Co. for 

 constructing an electrical railway from the Place de la Concorde to 

 the interior of the Electrical Exhibition. M. Alphaud has given 

 his adhesion to the request, which will be sent with his recom- 

 mendation to the Commission of Sewers appointed by the 

 Municipal Council, that when the Exhibition shall be closed, 

 the railway will be kept running in the Champs Elysees. 



Mr. Preece has been spending a few days in Paris in order 

 to report on the electric establishments and experiments which 

 are being made in that city. He inspected the electric con- 

 ductors of several large monuments, visited the telephonic 

 exchanges, the Meritens factory, where are being built the 

 magneto-electric engines ordered by the French ■ Lighthouses 

 Administration and the Trinity House, &c., &c. 



Those interested in sanitary matters should see the Preli- 

 minary Report to the U.S. National Board of Health on the 

 Relation of Soils to Health, in the supplement to the Bulletin of 

 the Board for April 16. The special point reported on is the 

 Filtering Capacity of Soils, by Messrs. R, Pumpelly and G. A. 

 Smith. J 



A MEETING of the Yorkshire Geological and Polytechnic 

 Society was held on April 27 at the Royal Institution, Hull, 

 under the presidency of Mr. A. K. RoUit, LL.D., F.R.A.S., &c., 

 ex-president of the Hull Literary and Philosophical Society. 

 There was a fair attendance, including representatives from 

 several parts of Yorkshire. A brief introductory address on 

 recent advances in physical science was made by Dr. RoUit, 

 after which Mr. G. W. Lamplugh, F.G.S., read a paper on 

 " The Peculiar Intermingling of Gravel and Boulder Clay in 

 some Sections near Bridlington." Mr. J. W. Davis, F. G.S., 

 hon. sec, then read and remarked upon papers by Mr. A. G. 

 Cameron of H.M. Geological Survey, on " The Subsidences 

 above the Permian Limestone between Hartlepool and Ripon," 

 and Mr. J. E. Clark, B.A., on "A Deep Glacial Section at the 

 Friends' Retreat at York." Dr. James Geikie, F. R.S., was 

 present at the meeting, and made some observations on the sub- 

 ject of geology generally. In the afternoon the Society made a 

 geological excursion to the east coast at Withernsea and to the 

 gravel-pits at Kelsey Hill near Burstwick, at the former of which 

 places Dr. Geikie delivered a geological address. 



About twenty minutes to eleven on Monday night, owinc j 

 some accident at present unexplained, the electric lights on the 

 Brush system, one of the three with which experiments are at 

 present being made in the City, were suddenly extin.;ui>hed, 

 leaving a large portion of the City in total darkness. The area 

 over w hich the Brush light has been placed extends from Black- 

 friars Bridge, up Ludgate Hill, to St. Paul's Churchyard, and 

 down Cheapside as far as Queen Street and King Street. For- 

 tunately the old gas-lamps remain in their places while the elec- 

 tric light experiments are being made, and orders were quickly 

 given for these to be lighted. Every attempt was made by those 

 in charge of the Brush light to restore the connection, and for a 



