playing on a true set of strings is very great, and is appreciated, and its importance felt far more by great players than by inferior ones; I have seen a certain mighty violinist throw away sixteen E strings in succession before he could find one that was absolutely true with his A. Another important matter not to be overlooked is the position of the bridge. Amateurs generally leave the bridge to take care of itself, and never touch it. Now every time a new string is put on the bridge is strained forwards at one point, and ought to be eased back and set exactly at right angles to the strings, and leaning slightly backwards; if this is not done it is sure to get bent forwards and twisted. This will have the effect of making the strings of unequal length, rendering it impossible to play in tune. In conclusion, I may mention a dodge which is often useful: if a string is false with its neighbours, try reversing it; as often as not this will mend matters.-BRATSCHE. [35423.]-Indiarubber Joint.Take black lead powder, mix with water till it forms a slack paste, with which paint the surface of the indiarubber. I have used this plan for steam-joints fitted with indiarubber sheet insertion, and it will, I think, be equally effective for the present case.— WYLIEL. [35423.1-Indiarubber Joint.-"West" must cut the inside of his washer so that it shall not be forced up between the boiler-plate and the top plate of his door, and the outside so that it does not lap over the outside of his door flange. Have both surfaces nicely cleaned from grease, &c., then paint with graphite (blacklead) mixed with water; or wet both sides of grummet and sift fine sand over them.-W. R. L. [35425.]-Dating Machine.-Cunningham, of Oxford-street, used to sell such a machine as "Trois Besants" asks about. I think it was called "Cornell's patent." The cost was only trifling— some 25s. or 30s.-and yet the date, month, year, and name and address were all printed by one stroke, H. J. HILLENNE. the change each day being made in a few seconds. methods of obtaining an angle of 70° geometrically. [35434.]-Angle of 70°.-There are several I give figures of two. In Fig. 1 I draw A B, -FINEM RESPICE. Be [35425.] Dating Machine. "Trois zants must have seen the apparatus at railway stations, and an obliging ticket clerk would show him the modus operandi. The same may be said of the post-office stamps. If he has a self-inking brass stamp, and there is an open space, he can drill four holes through, file them out square, and by using short brass type, which have a shoulder on them to keep them from going through entirely, and a small gland to keep them up to their work, he could make his own stamp act. The letters and figures for to-day should stand thus-JA 25.E. M. APPRENTICE. A FICHI FIC.2 [35426.]-Electric Light. In a DynamoMachine for producing the current for an electric light, you should employ wire No. 16 for the bobbins of the armatures, and No. 10 for the electro-making an angle of 60° with X Y. Bisect the angle magnets which serve as inductors. Put on so many BA Y by line A C. Trisect angle B A C (which is layers that the thickness of the coils is the same as an angle of 30°) at 1 and 2, and on the other side of that of the soft iron cores. If you want to produce A B mark off distance 1-2 at point E; then from A lights by incandescence, you must couple for draw line A D through E; then DAY is an angle quantity-viz., so that the current only passes of 70°.-I in Fig. 2 make A B an angle of 90° and through the active bobbins and inductors at a given AC an angle of 60°, then B A C is an angle of 30°; time; if, however, you want to produce a light with trisect this angle and draw A D through the point the "arc," send the current through all the next A C; then DAY is an angle of 70°. In Fig. bobbins and the electro-magnetic inductors. In 2, I show a method of trisecting an angle geomeany case the current must go through the latter;trically.-E. H. C. you can, however, make an arrangement so that a portion of the current only goes through the inductors and the remainder directly to the lamps. the The power to be employed depends upon efficiency of your machine and the number of lamps. With a good machine you would obtain a light of 800 candles with a 2-horse power engine, and another such light for each additional H. P.— WIESENDANGER. [35430.]-Legal. Thanks to "Sperans, Lincoln's-inn" for his brief though pointed answer. [35435.]-Porous Cells.-Try the effect of heat by placing the cells in a very hot oven or over a Bunsen burner.-C. CRAWFORD CORY. [35435.]-Porous Cells.-If you put the paraffinwax all over your cells, the pores are filled up and the action of course ceases. The paraffin should be put on for an inch only, not more. The cold cell should be dipped to the required depth for an instant in melted paraffin. Carefully heat your cells and keep them in a warm place for a few days, [35437.]-Co-ordinate Geometry.-Multiplying our equation by minus unity and adding to both sides, we get x+1=1 y, or, (x-1)= (y), which is the equation to a parabola with axis parallel to axis of y; vertix at point (x, y) and focus at point (x= }, y= 0).-WYLIEL. [35437.]-Co-ordinate Geometry.-The following is the most explicit way in which I can solve this question. The given equation is y=xx3. From this it is evident that the axis is vertical. Let the following figure illustrate the curve: A 30 20 # This question may be worked conveniently by means of transforming the co-ordinates, thus: Take A B and C D as axes, then the curve meets A B in (0, 0) and (I, O), taking O M as unity. Again, the co-ordinates of O, with reference to the first origin O, are (1, 0). Now transforming to new axes A B and EF, we see the old y is unchanged, but the old x becomes x+, so that y = (x + 1) (x+1)2 21. Transform to axes through O3 = (0, 1) viz., G H and E F, referring the co-ordinates to the last axes. In this case, is unchanged, but y becomes y +}, thus += -2x2+1 or, 4( 4), Y of the vertex being (,) with reference to the which is an equation to a parabola, the co-ordinates assumed axes through O. Hence the axis is found. -E. K. DIXON. [35438.]-Horizontal Engine.-You can increase the power of your engine if it is strong enough to bear the extra strains, and to increase it from 8 to 12 h.p. means not a little. Increasing the steam pressure and carrying it over a longer portion of the stroke will do it, which entails alteration of slide valve and eccentrics, and beware of your boiler, in fact look well to everything. One cannot advise in a case like this without seeing the engine and boiler, I would not recommend you to try the experiment without the advice of an engineer (not yours, he may know all about it; and if he does you ought not to be under the necessity of asking for the reason of your piston thumping, for being on the spot he has the best opportunity of judging). The body of the piston may be slack on the cone, a bolt or nut out of the junk ring, the boiler may prime, in fact many things only to be found out by observation or taking off the cylinder cover. I have an idea you have overstrained your engine and the damage can only be found out by inspection.-W. R. L. [35440.]-Mathematics. Assuming that you are familiar with the work which you formerly went through, I think the following would be the best course to adopt:-Keep still studying Euclid, with the addition of deductions, which are given as exercises in most treatises on the subject. It is necessary that you should be able to demonstrate problems of this nature with great facility, in order to do well in the higher branches of mathematics. In Algebra I would advise you to go through the same course When you again advance as far as the Progressions, as you did previously in Todhunter's large Algebra. go on systematically as far as chapter 41, on Interest. Then, as a supplementary volume to the subject, read the treatise on Theory of Equations The facts of the case are exactly as I related them./rubbing them occasionally with a cloth.-WIESEN- by the same author. Obtain Todhunter's smaller DANGER. However, if in the event of C or his agents being able to show that inquiries as to the whereabouts [35436.]-Shafting.-The two pulleys "Lees" of B were instituted, without success of course; or wants the diameters of are 5 and 7 inches, for the folif it be set up by C that, not having heard from Blowing reason. On the driving shaft he has pulleys for a considerable time (say four years), he concluded he was dead; would either of these pleas be accepted as a sufficient justification for the course pursued by C? Any further particulars concerning such a case would be very acceptable, not only to myself, but also, I dare say, to those of "our" readers who, like myself, are not particularly acquainted with such technical points of law. Would "Sperans" please recommend a good book dealing with such questions?-H. C. treatise on plane Trigonometry, which I think you may read in the order in which the book is written. If your leisure hours will allow you (after having gone through a portion of the above), you ought then to read Todhunter's Co-ordinate Geometry of Two Dimensions. As you are studying by yourself, it would be advantageous to obtain keys to any of the above which are published.-E. K. DIXON. [35440.]-Mathematics.-I would recommend Pott's Euclid (school edition) and Barnard Smith's Algebra.-H. J. HILLENNE. [35441.]-Nutmeg Lever.-The hair-spring 14-in...21-9912 should go in increasing spirals from the axle of the 7-in...10-9956 balance-wheel to a part of the frame and be there fixed; shortly before it reaches the frame it goes 32.9868 between two pins on the regulator-index (look at a CARL. watch with a magnifying-glass). Your spring has [35436.]-Shafting.-I think the following most likely got shaken from between the two pins, size of pulleys will serve "Lee's" purpose. To or one spiral has got caught in its neighbour.the 16in. put a 5in. and to the 14in. put a 7in. I have worked them out and find 5 and 7 respectively the nearest answers.-WILLING. POND. [35441.]-Nutmeg Lever.-Many causes occur to produce such as stated by "Young Mechanic." See to the following: Remove works from the case. The balance-staff may have too much end shake, or probably one pivot out of its hole. The balance spring often is found with two or more of its coils over the curb pins. Being "off beat" is a very common defect. If none of the preceding defects appear write again.-SECONDS' PRACTICAL WATCH MAKER. [35443.]-Oscillating Cylinder. -Turn the exhaust port into the steam port by means of a fourway cock.-C. CRAWFORD CORY. [35447.]-Pressure of Deep Water.-Yes; because the pressure of the water on the bladder exceeding that of the air, would tend to force the air out.-NATAS. [35449.]-Connecting Battery Cells. It is better to have all cells of the same form. The wire should be about No. 18 (B.W.G.).—NATAS. [35449.]-Connecting Battery Cells.-You cannot connect cells of different batteries for use, without reducing them all to the electro-motive force of the weakest among them. For connections use wire No. 16.-WIESENDANGER. [35451.]-Dexter Fret Saw.-I think H. Simmonds will understand the perpendicular motion if he will refer to my rough drawing. A is the flywheel, and from a stud E a connecting rod, B, connects it to the saw frame C, and as the flywheel revolves it gives the up and down motion. I have left out the rest of the saw.—A. J. H. parts water. Strain and evaporate to 6 parts. Add [35168.]-Equalising Power of Spring. way 1823, I am glad to be able to assist "Cadich A+B A 2 B the first differences of which are B, and the second differences=0. Take three terms, A+B+C XxXx-1, and for z unite 0, 1, 2, 3, 4, &c., and we have these results: A A+B A A 2B+2C is to go to a really good patent agent; if he [35474.]-The Hands.-I should advise T. L. [35476.] Copying Paper.-"Wax" can copy any printed matter, such as paragraphs, pictures from Punch, &c., by simply wetting a piece of stiff paper or card and rubbing it as described with an agate burnisher, old toothbrush, or any similar [35452.]-Railway Passengers.-The follow-thing. If the printing ink has got dry through age, ing table which I have compiled from the Board of or being kept in a hot room, moisten it with some Trade Returns, shows the number of Passenger spirits of wine. I have copied engravings 70 years journeys (exclusive of journeys made by season-old by thoroughly moistening them with "toilet ticket holders) upon the railways of the United vinegar" first and then rubbing them, with a piece of Kingdom, for the four years ending 1869, the four note paper on them, with a burnisher. Don't put years ending 1873, and the years 1874, 1875, 1876, the newspaper on a hard table, but on a blotting and 1877. pad.-DISPART. Years. Number of 1875. 1876.. 1877. .477,840,411 A +4 B+ 12 C, B B+2C The second differences are 2 C, and the third dif- -a, c- ·b, d- - c, &c. P=b — a, Q = c − 2 b+a, R = ¿ -3c+3b. a, &c. Now, for a unite 0, 1, 3, 4, &c., and the successive corresponding values of y being a, b, c, d, &c., we have the following equaA, A+B, c=A+2B+20, d=A+3 B+6C+6 D, &c. Hence, A=; c- - A-2B c-26+s Bb-a-P; C = = 2 d-A-3 B-6 C d-3c3b-4 2.3 QXxXx-1 [35478.]-Cutting Hardened Steel. You should try the sand-blast process. I understand + +&c., where the law that worn files, surface plates, circular cutters, &c., of continuation is manifest. We will now investimay be sharpened so as to cut equal to new. This process was illustrated and described in the ME- gate the rule for interpolations when the intervals CHANIC some months back. The Sand-blast are not equal. Let y=A+Bx+CXxX1-p Works are in Gray's-inn-road, London (near Hol-+ D x x x x − p × x − q + E × × * -p Xx-qxxr+ &c. Now, when ro, p, q, [35479.]-Cementing Floor of Wash-house. r, s, &c., let the corresponding values of y be a, b, -After taking up old tiles, if you find a concrete- c, d, e, &c.; hence, a = A, b=A+Bp;c=A+ bed under them, dig off any uneven places, and Bq+CXqXq—p;d=A+Br+CXrXr-p water the same for taking cement; if not, you must+DXrXr-pXr-q;e=A+BXS+C make a concrete composed of one part lime to three of born. J. E. M. rough gravel laid about 2 inches thick, and let it stand X8+8-p+D X 8 X 8-pXs-q+EX The journeys made by season-ticket holders in the Portland cement to 2 of freshwater sand, not very Aa, B a day or two. In mixing the cement use 1 of best X 8-pX s − q x 8 — r, &c.; hence, b -a c-a-Bq. year 1876 were estimated at 101,000,000; and in rough, then lay it on the concrete about of an qXq-p the year 1877 at 105,000,000. The returns for the inch thick, and smooth over the surface and let it year 1878 have of course not yet been published.-set.-W. S. T., St. Columb Major. C. E. S. [35458.] Chloride of Silver Battery. Select a small ruler the thickness you require your rod; fold round rod one coating of writing or note paper, continued over the end of ruler; then pass round two or three thicknesses of note paper which have been dipped in melted beeswax. To make a case, about half an inch thick of moist pipe-clay or [35489.]-Differential Gear.-Not having Xxx x china clay or common clay will do. Take out the seen the description in Iron, I presume it is the same ruler; do not dry the case; make a small loop on gear as applied to turning lathes; if so, the ratio of X x X x-px x − q silver wire place in position. The chloride of e-a- -Bs-CX8Xs-p-DXsXs-pXs-q silver should be precipitated from nitrate and the speeds is as 16 to 1, therefore 16-12 revolu-+ 8 x 8 — px 8 — q X s — washed with that water to remove any lead, if any, tions per minute. This gear is well adapted to x x x x -p x x -q x x -r+ &c. I will just then fused in an evaporating porcelain dish, and turning lathes, giving a steady, regular, and silent give one example. Let the place of a planet at when fused like syrup, pour into the case. Re- motion, which is a great boon to amateurs. For midnight be as follows:-On Nov. 8th in Leo 10° move when cold. This is known as horn silver.- description and illustration of this lathe gear, see 14 6 36,846" = a; on the 9th in 10 28' 15" SMITH. E. M., Aug. 24, 1877.-JOHN CANNING. = = 37,695' b; on the 11th in 11° 4′ 10′′ - 39,850' [35460.] Poultry. - The addition of a cock [35489.]-Differential Gear.-If T. Westwood = c; on the 14th in 12° 2′ = 43,320′ = d; to find would not have been likely to increase the number will turn to the ENGLISH MECHANIC of August its place on the 11th of November, at the 6th hour. of eggs laid by the hens, especially in a proportion 24th, 1877, page 586, he will find this beautiful gear to pay for expense of his keep. "G.P.A." evidently fully described and illustrated as applied to a turnunderstands the management of poultry. I offer ing lathe. I believe this will be the lathe gear of (merely as a suggestion) the advice of an introduc- the future, the motion being so smooth and noise- 849, C = tion of fresh blood at frequent intervals should a less. The difference of speeds is determined by the falling off in egg supply seem to result from no number of teeth in the large wheel, and the difother cause, and the keeping of fowls of three difference of the numbers of teeth in the two wheels, ferent ages rather than all of the same.-WM. S. that is, as 16: 1 :: 200: 12 revolutions a minute.TRAVIS. A. TURNER. [35466.] Cement for Ivory and Metal.- [35491.]-Interpolation.-As I possess a copy I.-Dissolve 1 part isinglass, 2 parts white glue, in 30 of Vince's Astronomy," 4to edition, published in 101 × 3 × 2 × = 40,144′′ W. MORLEY. SCOPE TELE. [35497.]-Daniell's Cell.-The strength of the sulphuric acid has scarcely any effect upon the electromotive force. Its effect is upon the internal resistance of the cell.-SIGA. [35499.] Refining Silver.-It probably contains spelter. You cannot refine silver in a forgefire. You may perhaps purify it sufficiently for your purpose by heating it for an hour or two in Fletcher's perfected gas-furnace, but the simplest and cheapest plan is to send it to a refiner, who would charge 6d. for an assay, and give you the value in fine silver, less 2d. per oz. for refining.-W. 11° 9' 4", the 5. Mr. W. Kirtley's Tank Engine, for the Metroplace required. "Cudich N'Rhi" will also do well Co., Glasgow (101 to 109), and the other 9 (65 to 70 18 in number; 9 built by Nielson & politan traffic. to consult "Brunnow's Spherical Astronomy,' and "Loomis's Practical Astronomy," where he Willows, Lancashire, 1875. 4 coupled leading, inand 110 to 112) at Vulcan Foundry, Newton-lewill find, the subject of Interpolations treated of.-side cylinders, trailing end carried by a 4-wheeled bogie, inside bearings only to all wheels, flush boiler, [35494.]-Drilling Pipe Stems.-Use a tool steam-dome on middle of boiler, Ramsbottom's made like half-round engineer's boring bit.-TELE-safety-valve over fire-box, cab, wing tanks; colour, dark green. The above are, perhaps, the principal engines running on the L. C. & D. line.-G. L. P. [35509.]-Malleable Iron. In reply to "J. W. F." perhaps the following will be of use. In Calvert's "Mechanics' Almanack," which I have, on pages 50 & 51 there is a very good account of the preparation and strength of this metal. The description is so long, I fear to trouble you with it, and it would take a long time to copy, and as the little book in question is a very cheap one, it would not be wise to spend two hours in copying it.-TOM. [35511.]-Cast-iron Rusting. “Keighley" | wants to cure his washing pan from rusting, as it completely spoils all the clothes" washed in it. Yet it is "used every week," notwithstanding this desirable result. Is not this an almost incredible abuse of language? If such speech is silver, what should silence be? One would think that to omit washing for a week would be sufficiently profitable by saving the clothes-to pay for the substitution of a copper vessel, which would not rust! To make such a substitution is really the best advice I can give "Keighley." No kind of paint that I am aware of would stand boiling with (probably) soda, or washing powder, or soap-not even the silicate paints, nor water-glass, &c. He might try this: thoroughly scour off the rust with sand or emery, then, after each using, carefully wipe the pan dry while hot, and grease with tallow or oil to prevent rusting again. When next required for washing, bine with the grease and form a kind of soap-no use some caustic soda in the water; it would comdetriment, of course to the clothes.-DAGHBERT. [35511.]-Cast Iron Rusting.-I think the only cure is to have it galvanised.-A., Liverpool. honour man, [35500.]-Nuisances.- "Harrow's" is certainly a peculiar case. Suppose him to be a "peace-with" and therefore objecting to laying of poison about or the surreptitious use of the air-gun, it is difficult to see what he could do better, under the present defective state of the law of trespass, than keep a bully to drive nuisances and their owners away. The upshot would be that in any action brought he would, like the Roman Catholics in England, become defendant; and in due course, therefore, would have to be informed what the legal remedy was, simply because the legal authorities must wake up some time or other to the fact that it was a duty there was no escaping to give a decision one way or other.-MOLLY MAGUIRE. [35501.]-Thick Writing Ink.-There is a fault in the manufacture of this ink by "the best known maker," or it would never get thick if made of galls only, as best quality ink should be. The only remedy is to throw it away and try another.— INK MAKER. [35501.]-Thick Writing Ink.-A few drops of brandy will prevent ink from thickening or freezing, and a tiny pinch of salt will prevent its turning mouldy.-H. F. N. [35514.]-The Electric Light.--All the known lamps (except Jablochkoff's candle) for obtaining the electric light either by the "arc" or by incandescence can be employed with my 30 or 40 cell battery. The lamp described by "W." could be made by amateurs." I will describe a lamp and give drawings as soon as possible.-WIESENDANGER. [35503.]-Mining.-I divide this question into three heads-viz., 1, given a rope-roll 5ft. diameter to wind from 45 fathoms with ropes 1.375in. thick, and allowing two laps of idle rope on the roll at starting, find number of revolutions for the entire [35520.]-Plating Lamp Reflectors.-If you lift. 2nd. Find diameter of another rope-roll to be want to replate old reflectors you must use the placed on same shaft, and to wind from 68 fathoms. electro process. The copper for lamp reflectors is 3rd. At what point will the ascending and descend-generally silvered before it is cut up, as I have seen ing cages pass. First. Let R=no. of revolutions large sheets of it.-Os. VI [35522.] T then R = When L = = D 2 T depth of pit in inches D diameter of drum in do. and T thickness of rope. From this we get as the value of R 12-5 revolutions LRT for entire lift. Second, D= R Here dog, A. should proceed by summons before a not give any definite answer to the question because toothing plane to the panel and veneer, then pro[35528.]-Veneering.-I would first apply a vide two stout "flat" pieces of board, one under and the other to lay over the veneer, placing the whole under the bench or in an empty box so that uprights could be easily brought into action to press firmly together. Then in a warm room apply boiling water to the outside of veneer, whip on the glue on inside and on panel like "greased lightning," lay one on the other and apply in the centre a large hot smoothing-iron or tailor's goose in gradually increasing circles to outside edge to remove superfluous glue. Up with the sticks previously cut a little longer than the height of box so as to apply pressure by tapping them equally with a hammer, use the best glue, and not too thick, as most amateurs are wont to do. Note.-All articles to be firmly glued together "must" be pressed tightly together until the glue is dry, in order to force out the superfluous glue, as the less of it the better is the job, bearing in mind that the glue must be of that consistency that it will drop nicely from a brush in a continuous stream without separating into drops.-A., Liverpool. [35532.]-Proof Spirit.-"Proof spirit" was so called because in pre-scientific ages it was customary to levy duty on spirits by a rough-and-ready process, called the proof, and conducted as follows: -A small heap of gunpowder was wetted with the spirit to be tested, and the wet spirit was then set alight. If the spirit was strong the gunpowder became ignited and flashed off very soon after the spirit was lighted; but if the spirit was weak, the water left behind it as it burned off wetted the gunpowder so that it did not explode. A careful investigation of the true constitution of the spirit showed that the weakest spirit capable of igniting the powder had the following composition by weight:-Alcohol, 49-24; water, 50-76; specific gravity, 920. This is known as proof spirit. ΚΑΡΡΑ. [35533.]-Sewing Machine.-The rotary hook of your machine should not have been driven out without loosening the set screw, which is generally placed in the centre of the small pulley. The proper adjustment of hook to the eccentric is for needle to commence the upward movement immediately the heel of the hook has passed it. Tighten with set screw. Probably you will have to get it adjusted by an experienced adjuster.-S. M. M. [35535.]-Photographic. - To "FINEM RESPICE." The chrysoidine non-actinic varnish referred to entirely replaces the yellow or ruby glass usually used by photographers. The only difficulty is to avoid spots or pin-holes in laying it on, and this can be insured by first pasting on the window fine tissue paper and then varnishing over it. The gelatine process is far the most sensitive known, and whatever will answer for a non-actinic window for it will certainly do for any other. I can print a transparency on my gelatine plates through a non-actinic (?) window that will thoroughly protect an ordinary "wet plate."— FINEM RESPICE. Dynamo-Electric Machine. — 1. Use wire, No. 16, for the coils on the armatures, and No. 8 or 10 for the magnets, both double cotton covered and insulated with sealing wax-varnish. Make the latter by dissolving crushed sealing-wax in methylated spirit. 2. The armatures may be constructed of malleable iron, but in this case they should be made of two halves and the joint painted with Brunswick black or sealing-wax varnish. If D= 107-6in., or 8ft. 10 in. Third. I cannot they are made of one core each they will soon give an exact formula for, but by a rule of thumb become unduly heated, and you will obtain unsteady M. C. T. to get "Concrete: Its Application to [35534.]-Concrete.-I would strongly advise calcution, I find the meeting point will be at the action. You also will get more current with the 7.54 revolution, that is at 176ft. 8 in. from the surface.-HENRY PALMER, Nunnery Colliery, Sheffield. halves, and the successive magnetisation and demag-tains much that is useful to concrete builders.-A. same driving power if the cores are constructed in Building Purposes," by Potter (Spon). It will give him all the information he requires, and con[35507.]—L. C. and D. R. Engines.-1. Bogie netisation will take place more completely and more F. PARISH. Express. Designed by Mr. W. Kirtley, built by rapidly because you prevent the Amperian currents Nielson & Co., Glasgow, in 1877, numbered from circulating in the core itself. These are the reasons 157 to 162 inclusive. Description: 4 coupled trail-why the Gramme rings and cores of induction coils ing, leading bogie, inside bearings to all wheels, are made of a bundle of thin insulated (by oxide) inside cylinders, flush boiler, steam dome on middle iron wires. 3. The magnets may be made of malleof boiler, Ramsbottom safety valve over fire-box, able iron (two halves) but not of cast steel, because cab; colour, dark green. 2. Mail Engines, "Europa' the latter, possessing more coercive force, does not class- see page 429, No. 719, of the ENGLISH MECHANIC. 3. Light Express Engines. Numbered from 32 to 52 inclusive, built by Sharp, Stewart & Co., Atlas Works, Manchester; Canada Works, Birkenhead; and at the L. C. & D. R. Longridge Works, Wandsworth; of various dates, some with and without names. There are several slight differences as to the kind and position of the steam domes and safety valves and boiler dressings, &c. The following description will apply to them all:-4 coupled trailing, inside cylinders, outside bearings to all wheels, and inside to the driving wheels, raised fire-box, steam dome on middle of boiler, safety valve over fire-box, cab or weatherboard; colour, various shades of green. 4. ScotchMain-line local engines, built by Nielson & Co., Glasgow, in May and July 1866; 14 in number, 81 to 94 inclusive, named after Scotch rivers and islands:-4 coupled leading, inside cylinder, outside bearings to all wheels, and inside to driving wheels. [35525.]-Legal.-Fowls v. Dogs.-The master The tender is carried on 2 trailing wheels fitted would be liable in this case if he knew that his dog with Bridges Adam's patent axle-boxes, allowing had a habit of killing fowls, but not otherwise. I lateral play to the wheels; raised fire-box, steam-suspect slight evidence would be accepted as suffidome at smoke-box end of boiler, safety-valve over cient proof of the existence of a habit so natural to fire-box, no cab, but weatherboard. I consider a dog.-SPERANS, Lincoln's Inn. these engines admirable for their work. They run the short expresses to Bickley, Farningham, &c., and for speed and steadiness are unequalled for their class. men. allow of such powerful magnetic induction as [35523.]-Spinning Beads on in. Brass [35536.]-Lathe Mandrel.-Take my advice and don't alter the square taper into a round hole. It is only on self-acting lathes (in my experience) that a round taper hole is desirable, in order that both the centres may be truly turned, and you will not find it by any means so easy to turn a taper round centre to fit accurately, as it is to fit the square one; then you will require to turn the ends of all your drills (say probably one or two dozen), and prepare a flat at the ends (to prevent them from slipping), or make a chuck with a square hole in it to take them. "How will you fasten the plug securely without softening the bearing?" I would put taper if the taper is an inch in length (you don't give size of lathe, but I suppose it to be about 4-inch centre); you can make a tool out of an old taper saw file; break off the tang, soften, grind up, make centre mark at heel, screw on a hand-vice to hold it by and gently send in with moving centre, applying plenty of oil. Having, of course, first bored the hole the size of the smallest diameter, [35540.]-Induction Coil. This depends a great deal on the quality of the insulation. If care has been taken in this particular it would stand about three large Bunsens safely. The best battery for table use is undoubtedly the bottle form of the bichromate, consisting of two plates of carbon between a zinc which slides up and down to remove it from the solution. Exciting liquid potassic bichromate 2oz., sulphuric acid 2 fluid oz., water one pint.-C. CRAWFORD CORY. [35542.]-Zinc Carbon Battery.-This battery wants fresh acid every time you employ it. It will act for 30 to 36 hours with one charge.-WIESEN DANGER. [35546.]-Organ.-The cost of the small organ referred to would be about £50 more or less, according to the builder employed, and its size, 5ft. +lft. 9in. The tone would be sufficient for a moderate-sized room, or it could be made loud enough to lead the singing of 150 persons; that depends entirely on the voicing.-J. D.-W. [35546.]-Organ.-I should advise "G. C." to purchase No. 676, March 8th, 1878, vol. xxvi, of the ENGLISH MECHANIC, which on page 634 gives a lengthy description of the St. Paul's Cathedral Organ, as well as the specification: The organ has Manuals: The stops are as follows:-16 to the great organ, 8 to the choir, and 8 to the swell, the pedal has two stops, and there are nine couplers. A description of this organ is also given in the number for June 26th, 1874, of the ENGLISH MECHANIC. -G. L. P. [35547.]-To Preserve Meat in Tins.-If you buy the indices for the last two volumes you will find full information on this subject. You can then procure the three or four numbers in which the replies have appeared.-Os. [35547.]-To Preserve Meat in Tins.-"De Stacey" will find Dr. Richardson's lectures to the Society of Arts, recently published in these pages, most valuable. Not only the whole process," but many processes, with the principles as well as the practice of them, are there given. Such a mass of information and suggestive theory has rarely been compressed into a course of lectures; but then Dr. Richardson's are rare. The lectures began in No. 706 of this journal, and are fourteen in number. The best way, however, of preserving "meat" is to let it live until wanted for use-if it ever is really wanted by human beings.-Daghbert. [35553.]-Photographic.-To prepare ferrous oxalate. Water 4oz. 8 fl. oz. 2 64 I Would drill it out and tap it, screw in a wrought [35571.]-Flaw in Steam-engine Cylinder. iron plug, and cut off and file up. Have done so more than once.—A., Liverpool. [35554.]-Electrical.-Probably the connections can construct a wooden trough with wooden parare at fault. Unscrew the binding screws at the titions for cells. You should coat the joints with top and the carbons will come off, well scrape the paraffine wax, or paint them with Brunswick black, metal where the connection is made, then scour the and keep the trough in a warm place till quite dry. rod to which the zinc screws, also the tube into Teak-wood is by far the best for acid-tight troughs. which it slides, clean the end of the rod where it Have two carbon plates and one zinc plate in each screws into the zinc, and put the battery together cell.-WIESENDANGER. work. Is the zinc worn out?-C. CRAWFORD CORY. again, and you will most likely find that it will [35555.]-Organ.-A clarabella would be too strong for the organ, but a small-scale open wood pipe, with inverted mouth, would be a decided improvement in every respect.-J. D.-W. [35557.]-Electro-Magnetic Machine.-Wire No. 14 is 2.03mm. or '08in. thick, wire No. 16 is 1-587mm. or 062in. thick, wire No. 18 is 1.219mm. or 048in. thick. You do not use or want to use a battery with your magneto-electric machine. Any attempt to do so will only bring you waste of money and efforts. The magnets are to be excited by the currents induced in the revolving armatures. WIESENDANGER. [35560.]-Chloride of Silver Battery.-Little current could be expected if water only is used, because the internal resistance would be enormous, and there would be nothing to aid in setting up the action except the little quantity of salt, in the water. Chloride of zinc solution should be used.-SIGMA. [35564.]-Negative Collodion.-Will it not pay tools male and female are cut on a "hob," which and straightened after the teeth are cut, and for a Hand. [35567.] Screw Cutting by [35571.]-Flaw in Steam-engine Cylinder.I once stopped a similar leak by boring an oblique hole in the steam port side and putting in a soft charcoal iron rivet. If your flaw is so situated that a long drill through the ports will reach it try it. A rust joint might answer, but it is very unlikely.FINEM RESPICE. [35572.] Railway Engines.-The L. C. & D.R. Possess at the present time 162 main line, local, and goods engines. That number also being the highest on any of their engines.-G. L. S. Macculloch in Transactions of Geological Society; [35573.] Geology of Channel Islands.Mr. Godwin Austin in Report of the British Association at Birmingham, 1849; Mr. Godwin Austin in Geological Quarterly Journal, 1851. Also "Duncan's History of Guernsey and "The Channel Islands," by Ansted and Latham.-A. E. Day CASTER. [35579.]-Improved Leclanche.-Horn carbon no doubt means the retort scurfing from which plates are usually cut.-SIGMA. [35580.]-Electrical Taste.-The action is comproduces the sense of taste, these nerves being plex. No doubt a direct action on the nerves arranged for that purpose, just as when the opti nerve is acted on there is a sensation of light. But the saliva is also decomposed, an alkali is set free at one pole, and an acid at the other; these do actually disintegrate the skin if the action is prolonged, and will produce sores.-SIGMA. [35581.] Registry of Bills of Sale.-Bills of Sale should be registered at the Master's Office of the Queen's Bench in King's Bench Walk, Temple. If "A Stitch in Time" wants to know what changes have recently been made in the law relating to such documents he should obtain (for a few pence) a copy of the Statute on the subject passed last Sear sion.-SPERANS, Lincoln's Inn." [35583.] Eccentric. If I understand this correctly, the answer is that an eccentric requires to have "all" the throw that you want, whereas a crank has only one-half of ditto.-A., Liverpool. [35583.]-Eccentric.-Find the exact "travel" of the valve, half of which is the distance from the centre of the eccentric to the centre of its revolu tion, if you have a direct connection with the valve spindle or arms-i.c., cranks of equal length ca the counter shaft; if not the difference of their "travel" will have to be taken into the reckoning. [35567.]-Screw Cutting by Hand.-The tap from which you desire to take the thread for your-FINEM RESPICE. chaser should be revolved at a good speed in the [35584.]-Organ Query.-I should recommend lathe. Let your chaser-which should be smooth the piccolo, and make the CC to same size as ten. I and soft at the cutting end-be presented upside in the principal, but cut the mouths very low and down, and firmly pressed against the revolving tap voice softly, it will then give life to the organ.until the threads are deep enough. Slant it a little away from cutting edge by holding a little higher than level. Harden dark straw colour.-S. M. M. feed happens to be put on.-FINEM RESPICE. J. D.-W. [35585.]-Married Women's Savings. - A married woman can dispose by will of such property Inn. as is referred to in this query.-SPERANS, Lincoln's Mix A and B in equal proportions for wet plates; it will act for a few plates. Dry plates I have not which is a parallel master tap of large diameter, [35567.]-Screw Cutting by Hand.-A "hob," tried. "E. C. R." may get the same information with a large number of grooves in it, is set revolvthat I have on this subject from the British Journaling in the lathe and the chaser blank" cut upon Photo. Almanac, 1879, p. 70, price ls., Greenwood, it by running it over it precisely the same as in 2, York-street, Covent-garden, W.C.-"DE chasing a screw in the lathe. I have cut several SANTRAILLES." chasers with ordinary taps, but in a screw-cutting [35553.]-Photographic. "E. C. R." will re- lathe geared up the same as if cutting the same quire some neutral potassa oxalate and ferrous oxa-pitched screw, but it is a risky job if too much cross-water has to rise in the piping. This rise is partly late; to make the developer: dissolve 80 grains of the first in 4 fluid ounces of hot water, then add 20 grains of the latter. Stir well with a glass rod, let cool, and filter. It keeps well in a well stopped bottle, but exposed to the air spoils in an hour or two. I developed 12 "quarter" (4 × 34) plates in the above quantity, and then found it useless. Mr. J. W. Swan says when it has become useless by exposure to the air it may be restored by putting in it a hank of fine bright iron wire, and the restoration may be hastened by warming the solution with the wire in it, and that this will also restore its activity when exhausted by use. Captain Abney says the ferrous (not ferric) citrate of iron and ammonia has the same property.-FINEM RESPICE. [35554.]-Electrical.-Examine your batteries carefully, and you will find that the zinc plates touch the carbons in some place, or that a connection has been made somewhere between them.WIESENDANGER. [35568.]-Magnetic Bell-pulls.-The magnetic room Growing. This question is complex. First, [35588.]-Hot Water Apparatus for Mushas to heating house: It is evident that the boiler is too shallow, and the pipes too near each other: they should be as far apart as possible, and the distance needs to hold some proportion to the height the due to the circulation in the boiler itself, but still more to the difference in the specific gravity of the warm and cooler waters in the ascending and descending systems; a good boiler, &c., has often been advertised in these pages. As to heating beds for culture, I saw a very neat apparatus for the purpose at the Paris Exhibition. It was simply a metal case with a double-bottom, containing water, with [35569.]-Patching Football Bladder. Get a and a burner of any kind, or lamp, placed beneath of course an opening or pipe to prevent explosion, small screw with a flat head and a small flat nut. and regulated to maintain the desired temperature. Put the head of the little bolt into the ball through Those which I saw were meant for parlour gardenthe hole and screw on the nut, which should be, of ing, and might be fitted up as ferueries, tropical course, rather thin. You will be able to hold the hot-houses, and so on, but the plan might be adapted head of the screw outside the rubber, and when you to any purpose with very little trouble, and where have screwed on the nut tightly you can file it off gas is available the temperature would easily be kept the nut inside if you like by placing it first on the or automatic regulators are in existence for the level. This will make it air-tight. You can put at about the desired point with very little attention, end of the screw.-Os. purpose.-SIGMA. [35591.]-Loose Railway Wheels.-Yes, they have been tried quite 30 years ago; the idea is a loose wheel turns a curve better than if fixed on the axle. An account was given of this method in the Engineer some years ago, but I forget the date. perhaps "A Novice will look to the back Indices [35569.]-Patching Football Bladder.-Drop [35554.]—Bichromate Battery. Probably the guttapercha on the hole two or three times until Covered.-WALLACE. connection to the carbon is destroyed by corrosion of the metal in contact with it. I have known a [35570.]-Bichromate Battery.-The carbon similar effect produced at the zinc where joined plates of a bichromate battery may consist either of to the rod. Test by another battery and galvano-artificial or sawn gas-carbon. The latter are cheaper. meter to see where the circuit is destroyed.-SIGMA. Each element must be in a separate cell; but you-Tox. [35593.]-Daniell's Battery.-You are quite right in using a concentrated solution of sulphate of copper. The battery will act well a day or two after being first charged, viz., as soon as sulphate of zinc has been formed in the porous cell through the action of the battery. If you do not get the desired results state your connections, sizes of different parts, and more especially whether your trough is water-tight and does not leak from cell to cell, and I will answer your queries.-WIESEN DANGER. QUERIES. [35598.-Emery Wheel.-I have an 8in. by inch emery wheel, which has been burst in halves by keying on a shaft. How can I mend it and fix it on the spindle again so as to be safe for running at a high speed again? supply of steam, and don't want to inject more than is necessary.-SOLUS. [35616.]-Hardening Bicycle Bearing.-Will anyone inform me how to harden the inside of the hub of my hind wheel. The hub is of soft iron and wears away very quickly.-C. S. (Arrow B.C.) [35617.]-Measurement of Sunshine.-Will someone give a description, with a sketch if possible, of the instrument used for this at Greenwich and elsewhere. [35618.]-Clacks.-Will any readers give figures of the various kinds of clacks used for heavy pumping.PRATICE. -E. M. APPRENTICE. [35619.]-Path of the Sun.-What would be the size and shape of a figure traced by the image of the sun formed by a glass globe, say 2in. in diameter, on a spherical surface at the focal distance from the globe, at the end of a year.-A. T. [35595.]-Hand-made Bank Paper. This paper is made in single sheets, in wire moulds, from fine linen pulp specially prepared and ruu into vats. In fact, it is just the old-fashioned process of making all classes of paper. Bank papers are now made by hand to secure strength, privacy, and uniqueness. The "water-mark is simply from a design in wire, stitched on the gauze moulds, which [35601.]-Chemical.-If, to a solution of 5 parts of raised design gives impression to the pulp. There iodine and 2 of iodide of potassium, in 40 parts of are six manufacturers in England, who make this rectified spirits of wine, I add a little liquor potassa, I get a class of paper a speciality. The largest and best bright yellow precipitate, insoluble in water and alcohol, firms are Messrs. W. S. Hodgkinson & Co., Wells. but soluble in ether, can any correspondent tell me what is thick, it seems to me not sensitive enough.-J. E. F. reaction takes place and what is the precipitate?-MEDICUS. Somersetshire; and Messrs. T. H. Saunders & Co., Dartford, Kent.-JIB. (35098.]-Extracting Oil from Cod Liver (U. Q.)-First well dry your cod liver and place it in a basin, then place the basin in a saucepan half full of water, and let it simmer for two or three hours; be careful not to let any water in the basin with the cod liver.-ALBERT SMITH. UNANSWERED QUERIES. The numbers and titles of queries which remain unanswered for five weeks are inserted in this list, and if still snanswered are repeated four weeks afterwards. We trust our readers will look over the list, and send what information they can for the benefit of their fellow contributors. [35602.-Atomic Weights.-Will Mr. Allen kindly tell me what are the "peculiar relations between the atomic weights of the elements," to which he refers in his letter, as it seems to me that the atomic weights of barium, strontium, and calcium, instead of differing, as is the case with methyl, ethyl and propyl, in an equal ratio, present no mutual relation whatever.-MEDICUS. [35603.]-Brass Alloy.-Can any reader inform me what alloy is used in the manufacture of a new kind of brass that is now being brought from America? It is used in the keys of nearly all the American locks and also for steam joints. It is a red brass, coarse-grained, tough, and turns up easily, it is also one of the cheapest kinds of brass in the market.-S. A. BATH. [35620.]-Air Pump Valves.-I have an air-pump (single barrel), which at present has no valves. What kind of valves are best, india-rubber clack valves, or conical metal ones? The piston appears to be intended to act without a valve, being formed of a cup-shaped leather, with the edge turned upwards; but as the leather [35621.]-Saltpetre.-How am I to tell pure saltpetre from impure? If I salt a ham or piece of bacon with saltpetre from one shop, it is always soft and wet; but when I buy from another shop, and cure with it, the ham or bacon is quite hard and dry. The difference, I am told, is in the saltpetre.-A SUBSCRIBER FROM THE FIRST NUMBER. [35622.]-Electric Light.-To "SIGMA "or others.I have 30 quart bichromate cells, each containing 1 plate of carbon and zinc-size, 7 x 34. I want a light ten yards from cells. What should be size of conductor and carbons to produce best result.-E. C. M. [85623.]-Organ Stop-In the church organ here, there is a stop of pipes which, after going up straight for about six feet, goes off at an angle of 90° for about two feet. I wish to know if someone will be so kind as to tell me [35604.]-Gold Paint.-How is the powder which is what stop it can be. I expect it is some eight-foot metal sold for gold paint made, and what is it composed of?-stop; but I can't find out what it is exactly.-ORGANIST. J. W. D. [35605.-Enamel on Gold Ring.-I have a gold ring which was at one time enamelled with blue enamel; but with constant wear, the enamel has cracked and fallen out. Would any of your readers kindly give me directions for re-enamelling it, so that I could prepare the enamel Since our last C. Crawford Cory has replied to 31861'; and do it myself.—J. W. D. Albert Smith 35098. [35606.]-Gilding Books.-Shall be glad if someone will inform me how to gild book edges, and how to decorate the backs, giving as much information as possible, with directions for making the mixtures required, .e., for coating of white of egg and water, &c. I have tried once or twice to gild edges, but find, when the leaves have been turned over a few times, the gilt has come off. I think, therefore, I have not had the proper mixtures.-G. T. C. [35607.]-Medical Coil.-TO SIGMA.-In am about make a medical coil in accordance with the instructions given by "Sigma," in the 10th and 11th volumes of the ENGLISH MECHANIC, and as I am anxious to make it as cheaply as I can, I should feel obliged if he or any other reader who has had practical experience, would give me some hints on the making of the contact-breaker (a vibrating one). I have never seen any electrical apparatus, and I am in the densest ignorance of how they are made. I should like to be told whether, in soldering wires to binding screws, a soldering iron is used. Would it not do to loop the end of the wire around the screw? Is there any absolute necessity of soldering platinum on the spring and screw of the break, and if so, what weight of it would do, it is very dear? İ trust "Sigma" will be good enough to answer my questions, and help me over my difficulties.-TAU. [35608.1-Poultry.-Keeping hens only for the sake of eggs, I should be very glad if "G.P.A." would tell me what food he considers best for this object. Also, does he keep his hens contined?-BIRKENHEAD FOWLKEEPER. [35609.]-Verge Watch.-Will "Seconds' Practical which keep good time in the pocket, moving so rapidly as to gain ten minutes or more per hour when laid flat.-A YOUNG HAND. some [35610.]-Aneroid Barometer.-Having, time ago, purchased one of large size, mounted in strong brass case, I found, on comparing it with a standard one, that it reads 0-63 too high. In every other respect, it is quite perfect, the daily changes agreeing with those of Steward's Barometer, as printed by the Globe. Can the brass cap, with the glass which carries the moveable index be removed, and the pointer be put back without injuring the instrument? If so, any instructions from "Mr. W. J. Lancaster," or other equally obliging contributor would be esteemed a favour.-ANEROID. [35611.]-Casting Steel.-Can any reader inform mould after the manner of cast iron. Why not melt it in me why steel cannot be melted and poured into sand crucibles? What is the plan adopted by makers of cast steel spanners and the like; and is the steel of the same quality as tool steel ?-D. R. N. A Powerful Spectroscope.-A new spectro-Watchmaker" state what is the cause of verge watches scope of remarkable power has just been brought to the notice of the French Academy by M. Thollon. Its chief feature is the use of sulphide of carbon prisms, which are closed laterally, not by plates with parallel faces, but by prisms of the form of Amici's e., having curved sides meeting at an angle (which, however, is much smaller than Amici's prism). The refringent angles of these prisms are in an opposite direction to that of the sulphide prism. Two of these compound prisms are substituted by M. Thollon for the simple prisms in a spectroscope, which he formerly described to the Academy. Without going into further details, we may simply state that an enormous dispersion is obtained; with a magnifying power of 15 to 20 times, the spectrum has a length of 15 metres. The angular distance of the D lines of sodium is about 12', whereas that produced by M. Gassiot was only 3' 6'. This instrument should throw considerable light on the structure of the spectrum, and M. Thollon has already noticed some interesting facts. The lines of sodium and magnesium present a dark nucleus passing into a nebulosity, which becomes gradually merged in the continuous spectrum. Many lines have been split up, and all that have been thus resolved have been found to belong to two different substances. One of the hydrogen lines presents a nebulosity without a nucleus. M. Thollon remarks on the magnificence of the spectrum of carbon from the electric arc observed with the new instrument. The spectra of iron, copper, and magnesium in the same arc were also seen with admirable clearness and brilliancy. These new spectroscopes have been constructed for M. Thollon by the able optician M. Laurent. [35612.]-Lever Escapement.-I shall be glad if "Watchmaker or any other kind correspondent can oblige me with a sketch and short descriptfon of the action of the above; have searched a lot of back numbers to save others trouble, but cannot find it.-D. R. N. [35613.]-True Spiral.-Is there any method of describing a perfectly true spiral? If so, the way to do it would oblige.-J. Y. L. [35614.]-Fungus on Milk-cans.-Would Mr. fellow-readers can help me with a diagram and dimensions [35624.]-Vinegar Adulterated.-A sample of vinegar is supposed to be adulterated with sulphuric acid. How would you ascertain the presence of sulphuric acid in vinegar?—AKROOMENOS. [35625.]-Clements Driver.-Can anyone give me a description and sketch if possible, of the above or any other useful driver, also, overhead motion, the best shape of uprights, and in what manner are they fastened to lathe-bed or standards.-D.R.N. [35626.]-Medical Coil.-I have one of these in case with small 2-cell battery of zinc and carbon plates arranged in a horizontal position. How is this excited? I was advised bisulphate mercury, mixed to a pasty consistence with water; but this failed to work the coil, although the galvanometer gave evidence of a current. I saw some time ago in this paper, Gaiffe's chloride silver battery advised for coil, will someone please tell me how this is arranged? I want something portable and small as possible. I should think, however, the present arrangement will answer when properly excited being made for the purpose.-WATTY. [35627.)-S.E.R. Engines.-Can any correspondent tell me why the 4 p.m. express is taken by a 6ft. single; also, if any of the 6ft. 6in. have vacuum brakes.-B. [35628.]-Safety Hooks.-Would any reader give drawing of the best safety hook against overwinding ?PRATICE. [35629.]-Mining.-In firing shots in the night-time, whether would you begin at the intake or return, and why?-PRATICE. [35630.]-Dry Soap.-How is the soapy smell imparted to dry soaps? Is it ordinary soap ground up with the soda ash, or something else! Irish moss, for example. -DRY SOAP. [35631.]-Miners' Questions.-How would you proceed to repair the sides of a shaft so as not to interfere with the ventilation? 2. How would you fix an ordinary bricking ring in bad ground? 3. A water ring. 4. How would you prevent surface water from getting into the shaft? 5. How would you place props in a steep mine? In wide work, when the roof is bad, which way would you carry the working face?-MINING STUDENT. [35632.]-Tallow.-Will anyone inform me a good way to test tallow such as used for steam-engines?— TALLOW CUP. [35633.]-Building Society (Property Tax).Will someone kindly inform me whether property bought through a building society is subject to Property Tax under Schedule A-AGRICOLA. [35634.]-Soda Test.-I shall feel much obliged to any correspondent who can inform me how to best soda as I understand there are various qualities? I want to be able to know good from bad before I use it.-N. J. B. [35635.]-Steel Pliers.-Can any of your readers say how the jaws of pliers are made so as to fit accurately into one another? Are they manufactured in two pieces or more, then welded?-J. P. [35636.]-Malleable Cast Iron.-Will "A. D. P." or any other reader kindly assist me with a description of the process in the manufacture of malleable castings in Iron-Information as to books on the subject will oblige -DRAUGHTSMAN, [35637.]-Leather Pressing Rollers.-I am a worker in the "Preparing Room" of a flax spinning mill. with certain kinds of flax, the leather pressing rollers "lick up" so very much at times, that they make bad work. Can any of your readers advise what I might do with the pressing rollers to make them work well?OVERSEER. [35638.)-Phosphoric Acid in Superphosphate.-Carbonate of soda in excess and a little nitre are added to the solution of the superphosphate, and the whole is then evaporated to dryness and gently ignited, |