October 16, 1885.] 



8GIEWCF. 



335 



to that of an open sewer. Several large indigna- 

 tion meetings have been held, as weU as demon- 

 strations of unemployed boatmen, etc. ; and depu- 

 tations have waited upon the Home secretary, but 

 all to no purpose ; this high official practically de- 

 clared MmseK powerless to act, in consequence of 

 the sanction of the law having been extended to 

 both proceedings. On one Sunday during the 

 warm weather, when the condition of the river 

 became practically unbearable, the water com- 

 pany, yielding to strong representations made to 

 them by medical men and others, raised its sluices 

 and allowed the whole volume of the river to flow 

 along its natural com-se. Tliis produced a partial 

 and temporary mitigation of the evils complained 

 of at a considerable loss to the shareholders. For- 

 tunately the summer heat has passed without 

 serious outbreaks of illness in the neighborhood, 

 but meantime the deadlock continues, and appar- 

 ently wiU continue, until the new parhament 

 reverses one or other of the decisions of its prede- 

 cessors. 



The condition of the Thames itself is an illustra- 

 tion on a large scale of the results of the same 

 legislative action, and has been the subject of in- 

 vestigation recently by a royal commission. The 

 Metropohtan board of works is the body charged 

 with dealing with the sewage of London as a 

 whole. At present the sewage of London is dis- 

 charged into the Thames mainly at two points 

 some miles below London bridge, one on the north 

 and one on the south bank of the river. The latter 

 station, called Crossness, which receives all the 

 sewage from the Surrey side of London, was 

 visited by the present writer, m company with 

 several other members of the Society of chemical 

 industry, last July ; the object of the visit was to 

 see the measures which had been taken by the 

 board for the purpose of diminishing the nuisance 

 caused by the sewage discharge at this point. For 

 a considerable period on either side of low-water 

 the sewage can be pumped direct into the river, 

 but at other times it has to be pumped into huge 

 covered reservoirs, which are allowed to empty 

 themselves at low tide. The amelioratmg meas- 

 ures consisted in running into the sewage duriag 

 its discharge a solution of sodium manganate, 

 mixed with a quantity of sulphuric acid supposed 

 to be sufficient to decompose the sodium salt, 

 Hberating a solution of manganic acid. The sodium 

 manganate was manufactured on the premises by 

 fusing caustic soda (of which there was a large 

 stock on the ground) with black oxide of man- 

 ganese. The inefficiency of the process adopted, 

 to do any real good, as well as its great cost, was 

 somewhat freely commented on by the visitors, as 

 weU as the cinide manner in which all operations 



were carried out. Several schemes are before the 

 public for dealing with the sewage of the north 

 bank of the river, some of which involve the use 

 of Canvey Island, a large low-lying tract of land 

 in the estuary of the Thames, where probably 

 sewage irrigation could be carried out on a very 

 large scale. We may perhaps recur to these in 

 future letters. 



The Society of chemical industry, before re- 

 ferred to, has just sustained a severe loss in the 

 sudden death of one of its most active f oimders 

 and past presidents, Mr. Walter Weldon, F.R.S. 

 Wherever the manufacture of soda from common 

 salt is known, Mr. Weldon' s name was a house- 

 hold word. Not himseK a manufacturer, his pro- 

 hflc brain devised a large number of most valuable 

 improvements in various details of ahnost every 

 branch of the alkali manufacture, including 

 bleaching-powder, etc. He knew ahnost every 

 alkali works in Europe, and his labors abroad re- 

 ceived the recognition of the grand cross of the 

 Legion of honor. His addresses to the society 

 were most valuable resumes of the position and 

 prospects of the alkah trade at the time at which 

 they were delivered, and such as probably no other 

 man could have written. 



LETTERS TO THE EDITOR. 



♦** Correspondents are requested to be as brief as possible. The 

 writer's name is in all cases required as proof of good faith. 



Flood Rock explosion observed at 

 Princeton, N. J. 



We had arranged to observe the arrival and char- 

 acter of the wave by reflection of images in mercury, 

 and precaution was taken to stop all movement of 

 pedestrians and vehicles within 500 or 600 feet of the 

 observatory. At eleven o'clock (standard time), Pro- 

 fessors Rockwood, McNeill and myself, were at our 

 posts. Between 11.05.25 and 11.07.40 we, all three, 

 observed, accordantly, a series of four slight tremors 

 which blurred the reflected images in a pronounced 

 manner. We now suppose they were due to trains 

 on the railroad three miles away, or to carriages on 

 the main street, distant more than 1,000 feet; but 

 at the time we had no doubt that they were due to 

 the explosion ; and so, at 11.10, T stopped the chrono- 

 graph, and took off the sheets. 



Having a spare half hour in the morning, I had 

 rigged up a very rude, but fairly delicate, vertical 

 seismoscope, which was connected with a cylinder of 

 the chronograph so as to make an automatic record 

 of anything vigorous enough to affect it ; but it was 

 not sensitive enough to feel the tremors above men- 

 tioned. While I stood at the table reading off my 

 sheet, suddenly, without any apparent cause, the 

 seismoscope magnet began to rattle. I immediately 

 took the time from the clock, and, all corrections ap- 

 plied, it gives llii 14™ 41s _|_ is ^ eastern standard 

 time, as the beginning of the signal. Mr. McNeill 

 instantly went to his instrument, and found the mer- 

 cury strongly disturbed : the reflected image was 

 invisible at first, but the disturbance ceased in about 



