Sept. 5, 1884.] 



♦ KNOWLEDGE 



203 



the iron, but this is abstracted and retained by the layers 

 of prepared sand undorneatb. The entire filter is thus 

 cDmposed from below upwards of : — (1) A perforated 

 plate 0", Fig. 27. (2) Fine gravel, S". (3) Coarse white 

 =and, S'. (4) Black pyrolusite, S. (5) Interoiediate per- 

 forated plate, C. (G) Spongy iron, I. (7) An upper per- 

 forated plate, C. It thus appears that, as the entire system 

 is constituted by a series of inorganic substances, the 

 liability to decomposition of the filtering medium is entirely 

 dispensed with, and, in consequence, a renewal need not 

 be resorted to more than once in twelve months. The 

 tiiter may then be taken to pieces, thoroughly cleansed, and 

 recharged, by following the simple directions supplied with 

 each instrument. 



Type V.—" The Patent Carbon Paper Water Filter," Fig. 

 'JS, manufactured by Messrs. S. H. Johnson & Co., of 

 Stratford, London, E., is constructed upon the principle of 

 combining a theoretically perfect mechanical strainer with 

 a chemical purifier of the highest value. Both of these 

 requirements are premised to he but temporarily obtainable, 

 and bearing this in mind the inventors have sought to 

 produce an instruajcnt which shall fulfil all the duties of a 

 perfect filter with the materials at hund, which can be 

 iriexpensively and readily renovated. 



*^#,.fe'v: 



Fig. 28. 



Stout filter -paper, into which a quantity of purifie(f 

 animal charcoal (from 10 to 20 per cent, of its weight) 

 has been incorporated, is held within a chambered frame- 

 work, and operates by means of the pressure in the main- 

 service or household supply pipe. The body of the appa- 

 ratus consists of a series of apposed compartments, each 

 designed to hold two circular discs of the prepai'ed paper, 

 so that a six-chambered instrument, such as that shown at 

 Fig. 28, would contain tweh-e of such filtering suifaces. 



The unfiltered water passes in at one side, and, after 

 nitration, flaws into the supply-pipe under pressure. The 

 substitution of fresh papers is provided for thus : — " The 

 filter can be shut off on both sides from the service-pipe, 

 a small disc run back, and the grooved plates and distance- 

 frames of which the filtering chambers consist can be opened 

 out, and the spent carbon papers changed in the course of 

 a minute or two. When screwed up the machine is again 

 ready for work." The entire arrangement is a novel device, 

 and practically .'•upports the theory upon which it was con- 

 structed, and which we have already enunciated. 



New Zkalaxd Coal. — The coal trade of the north island of Xew 

 Zealand promises to be extensive. Coal is found at the Bay of 

 islands, where a mine is in full operation. At Whaugharei two 

 mines are at present working ; at Raglan coal of good quality has 

 recently been found, and at the Mokau a seam of excellent coal 

 is seen cropping out to a great thickness for a distance of between 

 twenty and thirty miles. Besides these places, coal is now being 

 worked to a considerable extent at several points on the Waikato, 

 and a large seam of coal — between 50 It. and 6U ft. in thickness — on 

 the estate of the late Mr. Foots, on the Maramarua Creek, is ex- 

 pected to become a source of supply shortly. 



editorial (gosJsifp. 



A LESS sensational Presidential address than that of 

 Lord Rayleigh to the British Association this year it would 

 be difficult to imagine, and yet it is not without interest 

 for those outside of the comparatively narrow circle of 

 specialists in physics, to whom it primarily appeals. Among 

 the more notable points in it I may refer here to Crookes's 

 masterly discovery of the element Yttrium by the pre- 

 sence of a bright band in the phosphorescent spectra of cer- 

 tain earths, and the proof thence derived of its compara- 

 tively wide distribution. The researches, again, of Abney 

 in the ultra-red end of the spectrum, Langley's conclusion 

 (already adverted to in these columns) that the sun would 

 appear of a blue tint if viewed by an eye situated outside 

 of our atmosphere, and the description of Cornu's method 

 of determining whether any given line in the solar spectrum 

 has its origin in the sun or in our own atmosphere must 

 command the attention of all who possess the slightest 

 familiarity with the theory, or practical use, of the spectro- 

 scope. Michelsen's final determination, too, of the velocity 

 of light as 186,290 miles per second will be accepted with 

 interest by all concerned in the study of cosmical or astro- 

 nomical phenomena ; while, finally, Lord Rayleigh's brief 

 discussion of the tendency and methods of modern educa- 

 tion can scarcely fail to be valuable to a very large number 

 indeed to whom the very British Association itself is but 

 an entity of the vaguest and most shadowy kind. 



" There was," says the Book of A^onsense — 



" There was an old person of Phila^ 



Whose conduct was scroobious and wily " — 



conduct which apparently finds very sedulous imitation in 

 certain gentry who try to pufl' themselves in journals weak 

 enough to fall into the trap they set for them. I may 

 select two illustrations of this of which I have had recent 

 experience. The first is that of a so-called " Spiritualistic " 

 paper which has been moving heaven and earth to provoke 

 me into a discussion, with the sole object of getting a 

 gratuitous advertisement in the columns of Knowledge. 

 Its failure to do so has driven it nearly frantic ; but, surely, 

 in vain the net is spread iu sight of any bird. The second 

 eflbrt to use this journal comes from a gentleman who has 

 invented something — -what, I decline even to hint : but 

 will suppose, for the sake of illustration, that it is an im- 

 proved hair-pin. Well, the inventor writes to me asking 

 for an appointment that I may see his hair-pin ; and goes 

 on to suggest that I should (of course, by puffery) aid him 

 to introduce it into ladies' schools " for our mutual advan- 

 tage." It affords an instructive notion of the idea which 

 such a person must entertain of the social status, habits, 

 training, and ethics of the editor of a scientific paper, to 

 suppose that he would misuse its pages for the sake of the 

 proiit to be got out of selling hair-pibs (or anything else) 

 on commission ! 



I SEE that the 2i0th minor planet was discovered on the 

 night of the 28th ult. at Marseilles. It is much to be 

 deplored that the astronomers at the Observatory there had 

 not something more profitable to occupy themselves with. 



In addition to the letter printed on p. 206, I have re- 

 ceived another from Dr. Kinns, complaining of the para- 

 graph on p. 142, and containing scarcely veiled threats of 

 what he will do if I do not apologise to him. Such threats 

 trouble iiie but little indeed ; but Dr. Kinns — and every 

 one else — is entitled to the most rigid justice; and I 



