Maech 17, 1882.] 



KNOWLEDGE 



435 



trees ? Am I right in thinkin;; that grass under beeches is often of a 

 finer blade than nsual ? Why docs Mr. Allen exclude yellow at 

 pa}?e21 of '■ Evolutionist at Large ? " it surely predominates at least 

 in spring. — M. McC. 



[329] — PnosPHOREs* EXCE OK Fish. — What is the cause of the 

 luminous appearance, so striking in the dark, observable on the 

 inside of a haddock, chiefly about the bones, even after it has been 

 cured ?— Leon.vrd B. I*. 



[330] — Cliubi.vo I'lakts. — In our hemisphere, and in our 

 climate, of course, the sun rises on our left and sets on 

 onr right hand. Climbing plants, such as the hop, in con- 

 wqnence, it is believed, of the action between them and the 

 (un, wind round their supports in the same direction. Perhaps 

 ■ome of your botanical readers will tuU whether, in the southern 

 hemisphere (say at the Cape or Australia), as the sun rises 

 on our right and sets on our left, these plants wind round in a 

 similar direction, following the sun, and thus in a totally different 

 manner from those with us. Under the equator, might they not be 

 sometimes puzzled as to the direction they ought to take ? — 

 W. P. B. 



[331] — Evolution and Geology.— Dr. Wright, F.R.S., in a 

 lecture at Cheltenham a few days ago, declared the Lias formation 

 to be " the greatest possible stumbling-block to the theory of evolu- 

 tion, for he detied anyone to lind in this complete geological 

 chapter the slightest sign of any intermediate steps of life. If 

 palaeontologists could determine such steps, the world would soon 

 be convinced of the truth of evolution ; but in endeavouring to do 

 this, they would find the zones of life in the Lias a very hard nut to 

 crack." What reply do evolutionists make to this objection ? — 



ECPTEBIS. 



[332] — Mosses. — Can anyone recommend me a book giving the 

 English as well as the botanical names of British mosses ? Hob- 

 kirk's '■ Synopsis," and Dr. Braithwaite's " Flora " give only the 

 latter. — Eiptebis. 



[333] — Sakkara Tablet.— Will "A Member of the Society of 

 Biblical Archaeology" kindly let me know when the Sakkara tablet, 

 mentioned March 3 on page 379, was discovered, and by whom r 

 What kingly dynasties are mentioned in it, and where is Maspero's 

 correction of these dynasties to be obtained and read ? — Egypt- 

 ologist. 



[334] — Jupitee. — I should be glad of any information respecting 

 cause and nature of the red spot on Jupiter, also where to find 

 best description of same. — A. H. M. 



iReplitE! to ©unirg. 



[31] — Inte.nsity Coils. — Give the size and length of secondary 

 wire, together with the method observed in the construction of the 

 coils, then we may be able to assist you in determining the safe 

 limit of battery power. If the insulation has been destroyed by 

 " sparking," it wiU be necessary to unwind the wire until the faulty 

 part has been discovered, mend the insulation with silk dipped in 

 hot melted paraffin, and rewind the coil. — George Edwinson. 



[93] — Water of Ayr Sio.ne. — This stone may be cut with a disc, 

 or a atrip of sheet iron with sand and water, or it may be cut with a 

 fine saw, as slate is cut. — George Edwinso.v. 



[119] — Electro Plating. — The sis ounces of cyanide of copper 

 can be worked out of the plating solution in the course of a few 

 days by using a large anode of pure silver. Of course, the first 

 deposits of silver will be inferior in colour, because alloyed ; but I 

 knsw of no other practical method. Separation by the chemical 

 process would not pay for such a small quantity of solution. — 

 Gboege Edwinson. 



[152] — Nickel Plating. — To economise space here, I may men- 

 tion that two good practical articles were given on this subject in 

 the Mechanical World for Sept. 17 and Oct. 1, 1881. — George 

 Edwinson. 



[228] — Microphone. — Plates for this purpose, about 3 in. in 

 diameter, the volume of the current increasing with size of plates. 

 .\ny number nntU the required tension has been obtained. — George 

 Edwinson. 



[229] — Hair. — See, for accounts of almost instantaneous con- 

 version of coloured hair to white, vol. i. pp. 198-99 of Hinton's 

 " Physiology for Practical Use."— E. D. G. 



[238]--Electric. — Inductive electric force is displayed in the 

 space enclosed between the wires of a galvanic circuit, and also in 

 the close vicinity of such wires. The "co-efficient of induction" 



would be the sum total displayed by two inductors, the amount of 

 induction by one being known. — George Edwinson. 



[241] — Fai-re Accuuclator.— (1.) All the tongues of the lead- 

 plates destined to form the positive element of the cell must be 

 joined together. (2.) All the tongues of the opposite plates must 

 be joined together, and "look" the other way. (3.) In series, one 

 after the other, or side by side, as may be required. (4.) When all 

 the oxide of lead has been converted into the peroxide of lead by the 

 action of the charging current, the cell is fully charged, but the 

 " quantity of electricity it will hold " varies with the age, ic, of the 

 cell, for it improves with age. (5.) Open, if preferred, or protected 

 from dust by a cover of wood. (G.) Yes. A cell might be charged 

 with this force, or oven less. (7.) No. (8.) The force of the 

 battery does not depend u|ion the force of the charging battery 

 itself, but upon the amount of chemical energj- ilevclo])ed in the 

 cells by the charge of electricity. Perhaps the dischai-ging cnrrent 

 does not realise more than 80 per cent, of the force expended in 

 charging the battcrj-. — George Edwinson. 



[242] — Prose Compositkix. — The theory of English prose com- 

 position is admirably treated in Bain's "English Composition and 

 Rhetoric," 1vol. (Longmans); while original and useful practical 

 methods are suggested in W. S. Dalgleish's " Introductory Textbook 

 of English Composition," Is. ; or bound with the " Advanced Text- 

 book," 2s. 6d. (Oliver & Boyd).— E. D. G. 



[244] — Lecti-res. — The " Working Men's Educational Union," 

 some years ago, published an Illustiated Reporter^ containing lists 

 of subjects for lectures, and of diagrams published in connection 

 with those subjects. The list before me comprises sets of diagrams 

 in astronomy, geology, volcanoes, the steani-engine, the telescope, 

 the microsco])c, the mechanical powers, and twenty-nine other 

 subjects. These diagrams are now published, I believe, by the 

 Religious Tract Society. Those which I have used were rough, but 

 gocd.— E. D. G. 



[247] — WAKMTn at Night. — It is certainly conducive to health 

 to maintain the body at a comfortable temperature at night ; but 

 have a care in the choice of stoves to keep the room warm. 

 Unless the products of combustion, produced by a gas-stove, are 

 carried out of the apartment by a flue, they will counteract all the 

 beneficial effects of increased warmth. — George Edwinson. 



[263] — Vegetable Food. — If Provost P., or anyone else who 

 desires any information about vegetarianism will write to Mr. 

 Doremus, 30, Rochester-road, London, X.W., he will get informa- 

 tion how to begin. A few stamps enclosed will further procure him 

 some pamphlets. — T. R. Allinson, L.R.C.P. 



[270] — Blowpipe Chemistry. — " Amateur" seems to have puzzled 

 himself sorely over Colonel Ross's very clear instnictions for con- 

 structing his blowpipe. The piece of brass is to be soldered to the 

 large end of the 12-in. telescopic tube, the mouthpiece being placed 

 on the opposite end. " Amateur" will now see that there is no exit 

 for the air blown into the tube through the mouthpiece. The jet 

 (of which a drawing was given by Colonel Ross) is let into the tele- 

 scopic tube at right-angles to it, an'd about half-an-inch from the 

 stoppered end, fitting close on lines A and B of drawing. The hole 

 in the jet, between lines A and B, now forms the exit for the air 

 blown into the tube. The balloon is secured to the larger end of 

 the jet, and acts as an air-chamber or reservoir, and, owing to its 

 elasticity, a bellows. The brass nozzle is fitted to the small end of 

 the jet, and thus forms the only outlet for the air blown into the 

 tube. I hope this crude explanation will help " Amateur " over his 

 difficulty. He seems to have mistaken the jet, of which a drawing 

 was given, for the lube, of which only the dimensions were given. — 

 Pyrologist. 



[273] — Strength of Material. — There appear to me to be 

 several errors in the solution given by "Anderson." First, he 

 uses two different values for the distance between the guide-rail 

 and the centre pivot — namely, 917 ft. and 8 ft.; and, again, he 

 resolves an apparently vertical force into vertical and horizontal 

 components. Taking 8 ft. for the distance between the guide-rail 

 and centre pivot, and 25 ft. for the distance between the guide-rail 

 and the direction of the weight, the solution is as follows : — 

 30x25 

 5 — = 93 J = tension in tons on the centre pivot, 



30x33 . , ., ., 



— s — ■"123i = pressure in tons on the guide rail, 



1235 -93J = 30 = weight '" tons on the crane. — F. M. 



[274]^FoRAMiNiFERA IN Chalk. — Bmsh out with a hard brush, 

 well wash in water, and pick out with a needle, and mount in 

 balsam. — Albert Smith. 



[274] — Mi.scELLANEOus. — (3.) The following drawing-books may 

 be recommended to " Blozoon" : — 1. " Vere Foster's," Marcus Ward 

 & Co.; 2. Cassell's scries of "Popular Drawing-Books"; and S, 



