The owner has the benefit of being able to utilise the full height of his lathe centres, has a firm and convenient support for his rests, and can fix or shift them with the minimum of trouble. For those turners who come under divisions 2 and 3, the bed must be got up true. It should be planed at one setting, if possible; for the channel of the bed, which guides the tenon of the loose headstock must be parallel with the slide face, and the top of the bed parallel to the top or flat of the V, and square to the slide face. The slope of the V looks better outwards, but yet am inclined to think that it is not superior to the other plan. Certainly, the lip of the carriage has a better hold on the vertical back of the strip; but if this part wears away, as it surely must in the course of time, owing to the strain on it, the carriage will rock or tilt on the face, and I do not see how the sloping edge can help to take up this looseness. It seems as if the upper and lower V's were placed at a disadvantage from being on different sides. But in the other arrangement, if either part wears away, the slide will still by its weight tend to keep close to the face, and the lower V will prevent any looseness. In the plan, I have drawn the top V strip with broad wearing surfaces, and a tolerably wide flat and sharp chamfer; or, in other words, the V is of smaller angle than usual, and is cut down to get a good broad flat. Both the rack and the screw would be better in the space between the strips; but as this cannot well be more than 3in. wide by about 1fin. deep, perhaps there would not be room. Probably some of our pattern-making friends will describe the best way of moulding such a bed. Would it not be well to part the pattern along the dotted line, taking out the channel by a core, and wiring on the V strips, and casting them down wards. The sand in the lower space at the back of the bed to the left of the dotted line, would then rise above the general level of the half-pattern; would this cause any difficulty? There should also be a few slots through the piece from the V to the channel, and through the bottom of the latter into the ribbed space at the back. June 10. Orderic Vital. E. F. Baker. the same as series of valuable or ordinary chucks to them, on round constantly; the salt prevents the metal from certain conditions, which should run true on the oxidising, and when it is finally quenched at a bloodtransfer system, to one thousandth part of an inch, red heat the surface is so excessively hard that no but of course cannot tell how long they would last file will scratch it, and the mandrel is still so true so, through the handling of different workmen, to the collar to which it has been fitted that only a whether they are amateurs or regulars, as some have few turns with oilstone dust will be required to a great repugnance to keeping their mechanism in clean off the black. The extremely hard surface clean and good working order, tumbling their ap- obtained by the ferrocyanide is very superficial, but paratus and various tools under and on the top of a life's work at the lathe will not wear it through. one another anyhow; consequently it can easily Boring the back centre, or tail screw, be understood by this system of procedure, nothing the mandrel, is much a matter of fancy, and can remain true for any length of time. scarcely worth while as a wire-saving contrivance. I once worked with a foreign lathe with a hollow centre, which, used for drilling, worked unpleasantly hard. I should never use this back LATHE MATTERS. entrance for knocking out work or driving out the [22907.]-HAVING been much occupied for the front centre from the mandrel. This centre in my 6in. last two years, I have not been able to fulfil my foot lathe is fitted with a long taper, and jams promise of sending description and drawings of a in very tight; it has a cross hole, through which I novel screw-cutting arrangement. This I will do pass a tommy and twist it out. This hole I someshortly. As the question of lathes is now receiving times utilise for fixing a rod or dogs of various much attention in your pages, I venture to remark forms for light turning, thus dispensing with the that any attempt to establish a universal thread carrier and catch plate, which are often in the way for a mandrel screw is not likely to be successful, or cannot be used. I should not think of wasting because, amongst engineers and others, the Whit-my time by turning up small rods or wires in a 6in. worth thread, proportioned as in screw bolts, has lathe; a small one half this size is best for this long ago been considered and accepted as the work. As regards the friction of foot lathes, this standard, and is so mentioned in the catalogues of to one who works for hours at a stretch for days some of our best lathe-makers. It can be matched together is an important consideration. In order everywhere, and fitted perfectly without any diffi- to give stability to the chucks, they should have a culty, and any light turner that could not finish wide bearing on the mandrel face, and this, therethe thread off with a polishing cut, and an air-fore, must be of considerable diameter; but many tight fit in the gauge nut, and draw the tool slide run into the error of proportioning the length of the out to the last turn so as to bring the bottom of the bearing to its diameter; all the lightest-running thread up to the surface, might seek employment foot lathes that I have seen have very little depth elsewhere. The pitch of the thread is not too of collar, and yet, after years of use, show coarse for the diameter. Many of our best brass- no signs of wear. I know one very easy-running turners prefer even a coarser thread, because most 6in. foot lathe that has been in constant use of their work intended for accuracy is held in box- by one turner for over twenty years; this has a long wood chucks, and for them a fine threaded mandrel mandrel, and a depth of collar only half the nose is an abomination. A rotating cutter is all diameter of mandrel neck; but for all the work very well for cutting the spiral grooves in twist- that it has done there has been no wear in this drills, but it will not finish a machine screw accu- part. Your correspondent, "F. A. M.," contests rately, such as that on a mandrel. The chaser or this point on the authority of rudimentary treatises, any other cutter not consisting of a single plane but in the case of a foot lathe a large surface of oil must necessarily be a counterpart of the spiral of rubbed up is a creator of friction. My own 6in. the screw-thread, which increases in angle towards foot-lathe runs light, and yet has a very heavy TRANSFER CHUCKS. the axis; therefore, a straight prism will not fit weight to carry on the mandrel: this, with the the thread, neither will the angular edge of a cir- pulley and catch-plate, weigh 154lb., and if the [22906.]-As several illustrated ideas of transfer cular cutter. Where the most perfect accuracy of extra division or worm-plate is attached, 2111b. chucks have appeared in " our" ENGLISH ME-fit is desired no chuck should be fitted as left from The mandrel is 8in. long from shoulder to end, CHANIC, I shall be glad and pleased if you will the screw-cutting lathe, for the same reason that no 1in. diameter behind the collar, and at the neck allow mine to appear likewise. highly-finished hole should be left from the slide- the diameter is 1in. for the bearing face of the rest where a standard rimer is to be had. The chuck; the depth of the collar is in. The mandrel last fitting scrape should be given by passing nose is screwed to the Whitworth standard, in. through a plug tap the exact counterpart diameter, having nine threads per inch, and the of the mandrel thread; such taps should always mandrel is bored throughout with a hole. I be the accompaniment of every first-class lathe. always keep two oil cans, one containing sperm It would be better to have at least three-viz., a oil, and the other common benzoline oil. In order taper, a plug, and, lastly, the finishing tap, as it is to diminish the fag at a quick speed I use a drop not every amateur who has access to a screw- of the latter; the relief is immediate. I am always cutting lathe. His means of fitting a chuck would using this oil for easing clogged slides, and oilbe: first to remove the bulk of the metal by the stones and slips. hand-chaser, and then pass the taps through in succession. This being done it is next necessary to ascertain that the screwed end of the chuck bears equally against the mandrel. The rim of this is touched with reddle, and the contact parts scraped away till a bearing takes place equally all round then the finishing cut is taken over all parts of the chuck. This is a usual practice, and a precaution that should always be seen to by whatever means a chuck is fitted. This has been described in Holtzapffel's "Turning and Mechanical Manipulation," published thirty-eight years ago, which contains the best and most interesting essay on screw-cutting that had ever been written; and it is this firm, so eminent for excellence and accuracy of workmanship, with near a century of workshop experience, that is accused of malpractice, from the conceit of one that has had no practical experience this way. The best material of which to construct a lathe mandrel, is the mild homogeneous or Bessemer steel, that will scarcely harden by quenching at a bright red heat. The length, after being roughed down, should be bored quite through while revolving in the collar-plate with a twist drill or half-round bit. It should then be turned down to near the size and afterwards annealed. A plug of hardened steel, drilled through and suitably coned, should be driven in the end for the back centre, as this saves putting this end in the fire. The mandrel should now be finished, and finally a transverse hole drilled through, about an inch and a half behind the collar. This to me is very useful, as it enables a screwed rod with an eye to be used for sent a back centre one, that of B a screw, or tra- admitting a cross-pin through the mandrel, so that versing. The chuck No. 1, has a recess shown at anything with a central opening can be drawn C, which fits over the circumference of mandrels at hard up to a chuck face, or gripped between plates, A and B, which must be both the same size exactly, as for turning the edge of discs or building also fitting one and at the same time up to the face up glued woodwork. Finally, the screwed of each, thus making, as it were, two solid or sound end of the mandrel has to be hardened. fittings. The mentioned chuck can be relieved from This should be done at a very low heat, its first position and transferred to mandrel B, which to prevent warpage. Bend a stout piece of sheet has three fittings, two facets, and one circumfer- iron half round, to contain the end of the mandrel, ence, consequently will transfer from one to the other, or vice-versa. After 40 years of practical experience in mechanical manipulation, I believe that a true system of transferring is thoroughly practicable when the operation is conducted by skilled workmen. Of course there are now, as at former times, a quantity of near-enough men, who do very little better than talk big things or sheer twaddle, causing no end of mischief, but eventually justly find their proper level at the proper time. The illustrated mandrel A is intended to repre FICI FIC 2 8 If the mandrels are made perfectly true, and the fittings likewise, I would guarantee to make a and heat up gradually; as soon as the mandrel shows account of the perpendicular stroke of the treadle, Most lathes are unnecessarily hard to work on which is unfavourable for the free muscular action of the leg. The treadle should swing from a centre higher up than usual, so as to bring the centre of vibration near to a right angle with the hip joint; if the back centres are raised 1ft. or 15in. from the floor, the fatigue will be lessened; also the swing or connecting rod is usually set in the wrong place, for instead of being taken as a perpendicular from the crank spindle, so as to equally divide the throw of the crank, as in a double-acting steam engine, the point of oscillation should fall midways, and divide the front half of the revolution of the crank, as the whole force is given on this down stroke; this, with a short connecting rod, will cause a quicker rise or return stroke to the treadle, but this is no disadvantage. The hook of the connecting-rod should be lined with a half shell of lignum vitæ, which acts very smoothly in spite of dust. In a 6in. foot lathe with a heavy driving wheel, the centre support at this end is rather a weak point. If the crank axle runs in bearings or brasses it is apt to go hard. If supported by rollers, these at length will cease to roll, by wearing more in one place than another; a better way is to attach a roller to a short swing bar or lever close under the centre, the other end of the bar being drawn up by a bolt and spring washer, so as to raise most of the weight of the wheel off the centre. The front-slide lathe is not a novelty. I recollect a very beautifully finished foot lathe on this pattern, by Roberts, of Manchester, 40 years ago. Messrs. Cooke have carried out the idea very perfectly, and in such a substantial form that it will stand firm under very heavy work. I consider this the most serviceable form of lathe for the amateur mechanic; indeed, for some work, such as turning long slender rods requiring intermediate supports, it will easily effect that which in other lathes would be a difficult operation. I do not give much attention to fancy or ornamental turning. I use my lathes mostly for the construction of mechanism, but for this work the overhead gear, A. Yes, that I can. Out of a numerous list of such instances, extending over 13 years, I will select the most modern-viz, the successive tides for ten days between April 19 and April 29, 1884. They are as follows: Date. 1884. Calcu- Obserlation. vation. Errors. Bar., Wind, &c. drill socket, and extra slide-rest, cutting frames, SCIENTIFIC DIALOGUES ON THE TIDES.-IX. [22908.]-Q THE results obtained by the tables you have given seem sufficiently definite as to the heights and times of high water; but is it not desirable to have a means of ascertaining the height of the tide as marked on the gauge, at any time throughout the day as well as at the exact time of high water? A. This can be done only approximately. Various tables have been given in different works on the subject more or less accurate. I have recently contrived what has been termed a "tidedial," which shows at a glance the times of high water morning and evening, and the time of ebb tide; also the heights of high and low water, and the height of the tide at all intermediate times throughout the day. It is simply a graphical method of exhibiting the change of level in the surface of tidal water, which is alluded to by Sir G. B. Airy, the late Astronomer Royal, in his "Treatise on Tides and Waves," the principle being that the tide, in its rise and fall, will approximately cover and uncover equal arcs of a vertical ft. in. ft. in. 20 20 10 20 2 21 22 0 217 19 6 20 9 20 4 21 8 21 28 6 28 5 28 29 27 8 27 1884, gives an account of a public meeting recently convened at Rotherham to condemn the Yorkshire Sunday Closing Bill. The announcements invited working men to "Don the red ribbon, and come in thousands." Some 2,000 people assembled in the college yard, then a dray appeared for the speakers to use as a platform, and then several individuals who looked as if they had freely partaken of what are called "stimulants." A Mr. Bullen, who is said to have the honour of having founded "the red ribbon league," was present, and a Mr. Bellingham acted as chairman. There were also present Councillor Gregson and others, who appear to have come to represent those who did desire to have 30-0 E.N E., fresh. a Yorkshire Sunday Closing Bill. Mr. Bellingham, who described himself as "a Yorkshire artist," but of whom I have never before heard, was the leading speaker, and he is reported to have delivered himself as follows: Bar. falling. +3 28 6S.S.W, fresh. 3312 Mr. Bellingham said they had met that night to oppose the fanatical system of teetotalism that was brought against the comforts of the working men. The remedy of teetotalism meant that their morals were at stake. (Laughter.) The morals of the working classes were at stake. (Loud laughter.) The teetotalers said that the morals of the working classes were lost by going to a publichouse on 3 28 9 N.N.E.strong Sundays. (Applause.) He said that the morals of domestic society were enhanced by working men going to the public-house on Sunday rather than by carrying drink to their homes for Sunday. No one was justified in preventing a freshments on a Sunday if he liked. A man who working man who chose to go into the midst of beautiful scenery at Wentworth from having relived upon water all his life was not very beautiful have a quart of beer, whisky, sherry, claret, or to look upon. Why should not a working man port? (Laughter.) The man whose fanaticism wished to prevent a working man from having what he liked had no right to live. (Uproar.) He was an abomination to the laws of nature. He was would, stick out for keeping open publichouses entity, and said, "I am wiser than God." They and for sociability. between the 21st evening and the 22nd morning, Notice how the extraordinary jumps of the tide as also between the 22nd evening and the 23rd morning, are anticipated. Q. How do you explain the presence of such huge sandbanks in the estuaries of tidal rivers; they cause much impediment to free navigation, and are a great source of expense to the various harbour authorities? circle in equal times, whereof the radius is the half in very many instances, although perhaps not opposed to the laws of God, and made God a non A. If you glance at the map you will find that confluence of tides either of the same or of universally, these sandbanks are caused by the different ages, superimposed on each other. It is so in the Thames, the Severn, the Mersey, the Other speeches followed, then wild uproar; then Ribble, Morecambe Bay, and in the Solway. The the following resolution was put to the meeting by mighty tides which enter these estuaries meet the Mr. Bullen::fresh-water currents which descend by the river: channels from the hills beyond, and when their velocity is checked by impact on the land, and by collision with the stream, they deposit the mud and the sand which they have scoured up in their transit, and thus form the sandbanks peculiar to these localities. In the dial, as thus depicted, the time of high water is indicated at one minute before two o'clock, and its height 24ft. Also the ebb takes place at 35 minutes past eight. The height at four o'clock is seen to be 18ft., tide falling. The height at half-past nine o'clock is 8ft., tide rising. Q. As the heights of high water are so very variable in the course of the interval from springs to neaps, and vice versa, so in like manner must be the heights of the water at ebb-tide. Is not this the case? "That the working men of Rotherham, Masbro', and neighbourhood, assembled in public meeting in the College-yard, Rotherham, condemn the Sunday closing of publichouses as tyrannical and unjust, and an interference with the liberties of the people, and call upon their Parliamentary representatives, Messrs. Fitzwilliam and Leatham, to be in their Q. But it is generally thought that these sand-places in the House of Commons on the 18th of banks are continually shifting, and fresh surveys have to be made periodically in order to render the navigation more secure? A. The height of the water at ebb-tide has its diurnal inequality in a manner analogous to that which is observed at high water or flood tide; but the general rule is this: the lowest ebbs occur a day and a half before the highest spring tides at Liverpool, and the highest ebbs occur a day and a half before the lowest neaps. When there are two tides during the same day of unequal magnitude, the lowest ebb is that which follows the highest of them. A. It is quite true that the sandbanks at the mouths of rivers are perpetually changing; and a very satisfactory reason can be given why it should be so. We have to remember that when the moon advances from south to north declination, she sometimes crosses the Equator at an angle of 18°, and sometimes, viz., in nine years later, at an angle of 28°. Now this causes a vast change in the direction of the motion of the tidal current, for water has the property of retaining its direction of motion as well as its velocity, in a manner peculiar to fluids. The consequence of this is that the sands which, when deep below the surface of the water, are tossed about like feathers by the superincumbent pressure, travel along the bed of the sea in the direction of the tide, and remain in the place in which they are last deposited. More than this, the mouth of the estuary keeps widening, for old Neptune is too greedy ever to give back to its rightful owners the land which he has robbed from them by his successive encroachments. Q. You seem to assert that the predictions which are calculated on the theory which you have enunciated are remarkably in agreement with observation, and that the peculiar zig-zag alternations in the heights of successive tides are perfectly anticipated by your method. Can you give a practical example of this? ERRATUM.-There is a slight error in the working out of Example 2 of the time of high water at Liverpool on Aug. 1, 1884. For "Moon's lower transit B.," read "Moon's upper transit." James Pearson, M.A., F.R A.S. Fleetwood Vicarage, June 11. June next and speak and vote against the Yorkshire Sunday Closing Bill.” When the chairman called for a show of hands about 150 were held up in its favour. The word "contrary" was followed by a forest of hands and the waving of caps and loud cheers. The friends of Sunday closing, who had been somewhat indig nant that they had been refused a hearing, now turned the tables on the promoters of the meeting, and Councillor Gregson told the chairman that the majority was 100 to 1 in favour of the Sunday closing of publichouses. The wildest disorder prevailed for a short time, but the result of the voting having been ascertained, the great body of those who were in favour of Sunday closing began to move away. ALCOHOLIC BEVERAGES. [22909.]-I AGREE with Mr. Ansell as to the truth of what Johnston says-i.e., that "in the ardour of this crusade statements have been made by over-zealous champions of total abstinence which are not quite borne out by chemical and physiological researches." But what I don't see is how that fact bears upon the truth or falsity of what I said in my remarks at Bedford Chapel, those remarks being, as I understand, the subject of the present discussion. Will Mr. Ansell make that clear? Then, can Mr. Ansell point out any beneficent reform in which over-zealous champions have not made statements which break down on critical investigation? Take, for instance, those benevolent philanthropists who have lately adopted the red ribbon as the badge of a party which desires "to prevent a poor man from being robbed of his beer." A newspaper lying before me, dated June 2, Now, Mr. Ansell is a sensible man, and wishes t consider this subject fairly. What I would suggest is that I have no more to do with statements made by fanatical teetotalers than Mr. Ansell has to do with the arguments advanced, no doubt with purely philanthropic intentions, by this eminent "Yorkshire artist," and the founder of "the red ribbon league." But if we are to make a comparison between the red ribbonites and the blue ribbonites, I confess that I would rather go with the blues than the reds on this question. It would be very interesting to have a list of the philanthropists who belong to "the red ribbon league"" and compare it with a list of those who think that on Sunday the morals, and the wages, and the comfort of the working men are safer outside the publichouse than inside of it; who think that the working man excursionist who goes to see the beauties of Wentworth instead of spending his time inside the publichouse in the pursuit of sociability," should take with him his wife and his daughters and a comfortable "tea basket," and get at some cottage for a sixpence the use of a room and boiling water and a pint of milk. I confess I go with those who recommend him to adopt the latter plan when he goes to see the beauties of Went worth or to visit the beautiful gardens at Kew. It is not the publichouse or the sociability" that I object to; it is the drink and the associations which prevent the working man's wife and daughters from sharing with him the "sociability" and the "refreshment" and the beauties of Wentworth or of Kew. Referring for a moment to the other quotations from "Johnston's Chemistry of Common Life," we have two propositions submitted by Johnston in the paragraphs cited. One is that "ardent spirits, by the changes they undergo in the blood, supply a portion of the carbonic acid and watery vapour which, as a necessity of life, are constantly given off by the lungs." The other is "that they diminish the absolute amount of matter usually given off by the lungs and kidneys." Now if Mr. Ansell will show how as much energy can be got out of a man when his products of oxidation are diminished as when they are at their normal amount, he will have shown the principle upon which a machine for producing perpetual motion is producible. If Mr. Ansell will consider what I have said as to alcohol being always a narcotic or stupefier, whether taken in small doses or in large, he will see that Johnston's fact as to the diminished excretion of oxidation products is precisely what we should expect when the general sum of the man's working power is lessened-i.e., when it is under the effect of a narcotic. Under the action of a" stimulant" the man's oxidation products would be increased, just as under the action of a blower the fuel in a fire is burnt up more quickly, and the oxidation products which leave the chimney are increased in amount. James Edmunds. Grafton-street, Bond-street. FICT According to Professor Ferrini, one of Catella's armatures placed between the poles of a 60-light Edison (Zold pattern) instead of its ordinary armature, increased its power so that it could be used over 100 lamps." FIC 2 BEES AND THEIR STINGS SMO KING. lined with insulating material and entirely filled up | which print is to be made, with water containing with soft iron wire wound round. Then straight gelatine, and lay the wet paper on the glass, rubbing strips of copper, eight millimetres broad and two down flat with a straight-edge. Dry for about an millimetres thick, are screwed across the outside hour, then peel it off the glass, starting at one (like the bars of the Edison armature), from the ends corner. The print is perfectly waterproof, and can of one set of radial projections to the other, forming be mounted and washed. When putting the the parallelogram section. But in order to connect negative on the sensitive plate, place the ink lines the ring all round in a continuous circuit, these next the plate. After cleaning glass thoroughly, external strips of copper are connected at their two rub it with powdered French chalk, and the collodion ends to pieces which project not from the same film will strip off easier. If any of your readers [22910.]-MR. GRAHAM ANSELL'S theological internal strip but from adjacent strips. Thus the have tried this method will they specify which is argument (letter 22829)-I leave Dr. Edmunds to external bar will connect the anterior end of the the best sensitiser in their practice? W. C. M. deal with the rest of his letter-seems rather weak. first strip with the posterior end of the second, and He has not forgotten, he says, Who it was made the so on. Every third strip is carried along the axle wine at Cana. Has he forgotten, however, on the and connected to a segment of the collector. This other hand, who it was that said, "Look not thou construction is certainly simpler than that of the upon the wine when it giveth its colour in the cup,' &c.? And, in the face of that apparent contradic-Edison armature, and might be adapted to many tion, does it not occur to him that there is a previous different types of machines. question to be disposed of-namely, what sort of wine was it which was made at Cana? That there was a "wine" used by the ancients perfectly nonintoxicating, and therefore clearly not included in the very specific warning quoted above against even the " use of alcoholic wine, is well known; and probably Mr. Ansell is aware that the original Greek word was used indiscriminately for grape juice, whether sweet or fermented. The same difficulty occurs to those who seek support from St. Paul's sadly worn advice to Timothy, "Use a little wine for thy stomach's sake." What was the wine? And even if it were proved to be alcoholic, are we quite certain that St. Paul knew what was good for his friend's condition? Some people seem to think that that Apostle was specially inspired not only to preach the Gospel, but to prescribe infallibly for bodily ailments. Had that been so, surely he would have found his hands pretty full, I fancy. Lastly, let me remark that whatever this wine may have been, it certainly was not such wine as the port and sherry of the present day, because distillation, and consequently fortified wines, were known. T. B. C. PAPER WITH ONE SURFACE. [22911.1-IN my letter (22875) there are three errata: Line 1, for "stated "read" started." Line 25, after "other" insert fullstop. For "with" read "With." The construction seems to be much more simple than that of an ordinary Gramme ring or a Siemens armature, especially so if the strips could be procured ready stamped out. Could someone give me the leading dimensions I inclose tracings of the Figs. referred to.. POLISHING VULCANITE. [22915.]-WITH all due deference to Mr. Mundie (vide letter No. 22880, p. 327), I think he and other observers of animal and insect life fall into error by considering that insects do not vary in character, as well as all other living creatures. I have seen bees so fierce by nature that to go within a hundred yards or so of their hive was to make certain of a eting, no matter how little offence was given by the unfortunate human being who ventured near them. I have seen others which would stand great provocation before they attempted to sting. I must own to having a thorough disbelief in all hard and fast theories as to the behaviour of animals, birds, or insects. I believe they all have their characters as well as man. If "Os" (letter 22882, p. 328) considers that the desideratum in a pipe and in tobacco is to be able to smoke a maximum of the latter with a minimum of its special physical effects, I can only recommend dry Turkish tobacco and a new pipe for each charge. only say that I consider dry tobacco a waste of As a considerable smoker myself, I can money, and "clean" pipes an abomination. I suppose "Os" holds in abhorrence what are called "sweet" pipes? I doubt if many smokers will Garrison Gunner. [22913.1-THE polishing of hard rubber-whether it is called ebonite or vulcanite-is an art that is little understood, and as a matter of fact there is rather more in the skill obtained by practice than in the actual processes. The cutting and working into shape is done much in the same way that one agree. un- would pursue in the case of ivory or ebony, and when the turning and filing is completed emerypaper or cloth is used to remove all tool marks, and ELECTRICITY AS A VIBRATION. is best used dry. When the surface is freed from [22916.] (1) IN reply to your correspondent (letter all scratches, and presents a smooth, even appear-22854), I think his assertion is by no means a proof. It is then ready for the first polishing material, knows, not a plausible idea, but an experimental ance, it should be brushed or wiped quite clean. My suggestion of two opposite charges is, as he which is fine ground pumice stone and water, used fact; and, even on his theory, these two opposite on a cotton flannel pad or wheel, as the case may vibrations would cause the effect he states. The demand. Use this until the surface shows a fine, sound rupture is an intense vibration of the air, so smooth, dead finish. It should then be carefully violent as to shatter the gold-leaf diaphragm, for washed to remove all the pumice. It is now ready the leaf was not so tightly fixed as to vibrate for the third operation, which in nearly all common according to the sound, which it naturally would work is the last finish given, and consists in using do, like a drumhead, or any similar acoustic ARMATURES FOR DYNAMO. putty powder or oxide of tin and water on cotton arrangement. [22912.-YOUR contemporary, Iron, pub-flannel as before, in place of the pumice stone, lishes a paper read before the Society of Arts by which, if properly done, will give the article a fine Prof. Silvanus Thompson, in which the following gloss. In cases where the very finest attainable (3) If electricity is such a vibration, how do we paragraph occurs, and it will be no doubt of interest finish is desired for first-class work, the surface is get charges? for as yet we do not know how to pen to many amateurs. gone over again with lamp black and refined sperm-up vibrations; we cannot pen up sound, nor arrest oil used on the palm of the hand. There is one it. Agan, as far as we know, sound is purely word of caution, however, that should not be mechanical, and the essence and power of elecomitted, and that is, the greatest care is always to tricity in any case is not mechanical: it is an be exercised to avoid heating the work when polish- inherent property of matter, whereas sound is an ing, as that would destroy all. The results I gave I had worked out myself, as they are mentioned in Professor Tait's address; but I have not seen his paper on "Knots," to which he refers. Pl. My reason for calling your attention to it is in order to elicit information from those of your readers who may have constructed the armature of a dynamo on the same principle as to its efficiency and construction. Having recently been successful in the construction of a small Gramme dynamo, I shall probably undertake the construction of a larger and more powerful one, and for this reason also would be glad of information as to this particular class of armature. The following is the extract from page 478 of Iron for May 30, 1884 : "Before leaving the subject of ring armatures I should like to refer to a form recently devised by Signor B. Catella, which I think might be recommended to amateur constructors of dynamos as being easily made. Figs. 1 and 2 show its general arrangements. The armature resembles that of the Edison dynamo in being built up of copper strips. These are separately cut out, and consist each of a straight piece having two arms, and projecting at right angles. A sleeve of insulating material is placed over the axle, and round this these copper pieces arearranged to the number of 240, or so, having their arms projecting symmetrically round in two radial sets, one near one end and one near the other. The channel formed thus between the two is H. S. R. BLACK COPYING PROCESS. (2) I am arguing on purely experimental lines, not theoretical. abnormal state of matter. (4) Are, for, instance, other electrical phenomena explainable by your correspondent's vibratory theory?-as influence, induction, voltaism, thermo, and pyro-electricity. I fear it is not quite safe to say that electricity is a vibration, simply on the ground that a spark ruptures paper. (5) In the matter of resistance, I may go further than does your correspondent, and say a pipe resists the passage of water, air resists the passage of a bullet both such objections are as widely different as is his from the reality of electrical resistance, though they may look well metaphors. Cautious. THE ACCIDENT AT CHESTER AND FLORA OF EPPING FOREST AND [22920.]—THE Communications on the subject of REPLIES TO QUERIES. State to be stamped with the date of packing. The correspondent who does not give much information proposition was vigorously opposed by those in-about the parasites, but says 40 years ago he wrote terested in the canning interest, and did not become to the Lancet calling attention to the fact that law. The annual production in this line in the mackerel with worms were in season with the In their answers, Correspondents are respectUnited States-in fruit, meat, fish, and vegetables cholera morbus. Where are our biologists and fully requested to mention, in each instance, the title -is placed at 500,000,000 tins, or about ten for naturalists, or who can tell us something about and number of the query asked. every man, woman, and child in the country, and these worms? In my experience I have almost such a law, it was claimed by the manufacturers and always found these worms (Nematoda ?) in mackerel dealers, would seriously check, if not destroy, a when in their primest condition, and they are also [52520.] - American Organ. Like "Ornow prosperous business. It is not strange, how-to be found in bloaters at the same season-i.e. ganon," I am getting somewhat weary of the ever, considering the many forms of adulteration, Midsummer, at which time both fish seem to have a discussion, especially as very little light is being and sophistication in articles of food which superabundance of fat. The worms are mostly thrown on the subject. I think if "Organon" or have grown up in a few years past, that people are found coiled up on the roe, which, as a matter of Mr. Fryer had had the particular bit of experience very open to suspicion, and sometimes propose precaution, would not, of course, be eaten; but, if which has fallen to my lot in connection with this severe remedies. A great deal of glucose was sold we are to give up eating mackerel because of the particular instrument, they would admit I have in sugar and syrup and as honey before people worms, we shall have to give up eating a great good reason for the position I take. That position, suspected it, and the war between oleomargarine many other things-notably tripe, pork, and good briefly stated, is this: that good voicing is an and butterine and dairy butter seems now to be ness knows what else, for the microscopic worm the essential to good tone; but that unless the wood further than ever from a settlement, on account of bacterium seems to be everywhere and in every- (chiefly of the soundboard, and in a less degree of the passage by the Legislature of a law generally thing. I have some idea that Prof. Huxley, lec- other parts) is favourably disposed, a fiue rich deemed unconstitutional. The latest of these most turing at the Fisheries" last year, said that the diapason tone throughout cannot be secured. I conspicuous adulterations has been found in the worms in question were harmless even if eaten; should be very glad if the gentlemen named by recently-discovered adulteration of green coffee by and I have a suspicion that the "warning" exists"." would help us here, by, at least, giving an New York and Brooklyn dealers. The cheap only in the mind of some penny-a-liner, probably opinion on the matter. A maker of American Maracaibo and Guatemala coffees differ in appear suggested by members of the "fish-ring," who organs, in a large way of business, said to me some ance from the more valuable Java and some other don't like to see fish cheap. S. R. time ago, "We have just sent away the finestvarieties, the former being of a dull greenish hue toned organ we have ever produced." Now did he and without lustre, as compared with a glossy mean by this that his voicer had in that instance yellow colour in the Java. Thence was started a surpassed himself, or that, as I contend, and the practice of treating the cheaper coffees by rolling said maker agrees with me, the timber was prothe former in heated cylinders and sprinkling with pitious? The latter explanation seems the more gum-arabic water, to polish the beans and give likely, and accounts for the differences in instruthem more the appearance of Java. After this ments by the same makers, which certainly are not came the use of other colouring matters, and the all equally good. Coming back to "O.'s" remarks, officers of the Sanitary Bureau state that now both he may rest assured that the fault does not arise arsenic and lead are used for this purpose, as well from any defect of pallets or mute. I fail to see as chrome yellow, Prussian blue, yellow ochre, how these could affect the matter, if, as is the case, umber, Venetian red, and lampblack. The coffee they open wide enough, and close tight when shut. dealers say the injurious articles are used in quanNeither are the reeds loose in their cavities. "O." tities so infinitesimal that no harm can possibly seems to blame me for altering the sub-base; but come of their employment, but this is a statement if he had the misfortune (not fault, as he puts it) of which the public may well be highly incredulous; to find a bad result, after fitting it according to the the colouring matters have been used simply and plan given by "Elève," and recommended by only as a means of palming off a cheaper article himself, would he not have made some attempt to for a better, and the health officers have concluded remedy it? I have now fixed it vertically down that every cup of coffee made from the coloured through wind-chest, with free pallets over mouths beans contains one-sixtieth of a grain of arsenious of tubes, and find a considerable improvement in acid, a virulent poison. In buying coffee and many tone, and in the touch of that octave. I also think other articles of consumption, the consumer will "O." would fail to detect that any alteration had do well to be on his guard. ever been made. Perhaps, in describing the M. & H. voicing, the word abrupt was ill-chosen; but, certainly, the curve quickened as it approached the point, which was almost entirely below the block. I have seen good results from reeds with a less pronounced curve, and in some cases have obtained it myself. I would again thank "O." for the part he has taken in the discussion, and if he cares to reply to this, the matter may then be allowed to drop, unless Fiddler" or Mr. Schucht come forward. With regard to Mr. Fryer, I think I hardly understand him. First he says there is no difference in soundboards, and then goes on to say my experiment proves nothing: that, in fact, the M. & H. reeds were not adapted for any other board. Now, if reeds have to be thus specially tenor Creed from the M. & H. set, it is, within a boards are not all identical. Suppose we take, say, adapted to the boards, does it not imply that the trifle, the same size as a Munro reed, and notwithstanding its edges, will fit the Munro board, and the wind pressure will not vary more than is thus, to all appearance, in similar circumstances possible in any one instrument. Although it is the good tone is gone, and another, either more reedy or more dull, as the case may be, takes its place. Mr. Fryer admits the reed is good, and also argues that the board must be all right. If this is so, what I should like Mr. Fryer to do, is to tell me the reason the tone is not good, and to further explain, in detail, the nature of the adaptation required, as I fail to see what difference it can make to the reed which board it is placed in. His remarks about a different air pressure are not to the point, as, evidently, the reed can be, and is, subjected to a varying pressure in either instrument. A BOSTON despatch to the Providence Jurnal His seven conditions of good tone are all very well states that the recent experiments undertaken at in a general way; but depth of wind-chest is Harvard College to test the value of electrical certainly non-essential, as the finest tone I ever changes in the atmosphere as indications of coming heard came from a chest barely lin. deep. Mr. weather changes have been very promising. Though Fryer can find the method I adopt in voicing reeds the observations are not yet full enough to justify in an article by Eleve" on the "Munro Reed, decided statements, "coming changes in the direc-and How to Use It," in a back vol.-I think Vol. tion of the wind, rainy weather, and coming XXIII.—J. E. FLOYD. storms," it says, are foretold by the apparatus. 5631 - Electrical Testing.-Presuming The apparatus employed, which is substantially that Apprentice" has a Wheatstone bridge and that devised by Sir William Thomson, with some delicate galvanometer, join up battery to terminals adjustments, photographs every change in the Z and CE; join galvanometer up to terminals G, electricity of the air, and also indicates the degree GL. To test from 1 to 10w, the two 10 balances of change. at back of bridge should be open: 20 to 800w, the two 100 balances should be open: 1,000w, and above, the two 1,000 balances are open. Bear in mind that in the three sbere cases only two equiralent plugs are out, the others being closed. 1. Se that all pegs are firmly pressed in their holes. In putting a peg in it is not simply pressed in, but a screw-like motion given to it at the same time, care being taken that the fingers do not loosan other pegs. The bridge-holes and pegs should be cleaned at the least once a week, the pegs are leadei 122918.]-AN important report by Col. Rich has been published relating to a collision which occurred at Chester station on the 5th April between a passenger train and the buffer-stops, by which afteen passengers were hurt. The engine and tender belonged to the London and North Western Company, fitted with a steam brake and the simple vacuum apparatus; the carriages belonged to the Great Western Company, and were fitted with the automatic cacuum (of the leaking-off pattern, similar to that which caused the collision at Portskewet Pier, &c.) The brake pipes being the same system, the driver naturally expected he could work the brake on the carriages, and it appears that he did apply it at two stations; but, when required to stop at Chester, either the brake leaked off or the driver did not understand the automatic brake, the result being that the train ran into the buffer stops at the end of the station. Several railway companies use the same Clayton hose pipe, with various forms of vacuum brake. The result is that the pipes can be connected, yet the brakes will not work together. This fact has not been clearly explained to the servants on some lines. For instance, a Midland automatic vacuum vehicle which leaks off, another automatic vacuum as used on the L. and S. W., which does not leak off, and a non-automatic brake as used on the North Western may all be connected: a driver may be thus misled into thinking he has a brake throughout his train, when, in fact, he has control over perhaps only a few vehicles. Col. Rich, after giving details of the two brakes, reports: "It is a great disadvantage, as regards both safety, efficiency, and economy, that the great railway companies of the kingdom will not adopt a uniform system." The danger of using various brakes has over and over again been pointed out in your columns, but for years it has been clear that the companies never will agree until compelled, it is therefore to be hoped the Bill now before Parliament will be passed without further delay and before other accidents are caused. London, N.W. Clement E. Stretton. REPONSE AAN OLD PARISIAN lettre (No. 22831) d'An Old Parisian Amateur," autre. ses miroirs une figure parabolique; mais, s'ils ont J'ignore si "An Old Parisian Amateur" donne cette forme, je voudrais bien qu'il m'indiquat les moyens pas lesquels il y est parvenu, avec un polissoir dur et non-elastique. Je voudrais aussi savoir si l'on peut se servir de ce polissoir pour les petits verres qu'on travaille au tour. J'ai toujours trouvé le tripoli beaucoup inférieur au rouge, et à la potce, pour cette sorte de travaille: lequel, à l'avis d'An Old Parisian Amateur," Henry T. Vivian. doit-on choisir ? ME JOHN E. WOOTEN, general manager of the Philadelphia and Reading Railroad Company, WORMS IN FISH. patentee of the Wootten dirt-burcing locomotive, has sold his rights, says the Philadelphia Record, in 22919.] - A BATHER extraordinary announcement the patent for a sum estimated between 250,000dols has been made in some of the papers-viz., that a and 300,000dels. The purchase was made by an warning has been posted up at the metropolitan association of railway capitalists, who have formed hospitals cautioning the public against eating a company, of which Mr. Joseph Wharton, presimackerel, as they are infested with worms. In dent of the Wharton Switch Company, is the Vol. XXV. of this paper there is a reply from a chairman. |