dexterity. The above will give him work enough for the next few weeks; therefore I will say no more at present. Beale's or Carpenter's books will show him how to adjust and use the microscope, and the former shows all the operations necessary for the study of histology.-A FELLOW OF THE LINNEAN SOCIETY. [44790.]-L. and N.W. Engines.-Lucknow, Ap., 1868 Sirocco, September, 1874; Harrowby, October, 1878; Delhi, Ap., 1868; Senator, Sept., 1874; Peel, March, 1862; Hector, September, 1870; cent. profit; but of course it was not so, as they must be run in a crucible, preferably a plumbago one, as being cheap in first cost and lasting well also. On having a reply to my questions as to quantity, and if gas supply be available, I will give the desired information. But I should strongly advise a gas-furnace for small quantities.-SUNS LIGHT. [44794.]-Induction Coil.-Such a coil should give in. to in. spark; but if the insulation be imperfect, the spark might be shorter, though [44803.]-Firegrate for Lancashire Boiler. perhaps not altogether invisible.-J. BROWN,-Your boiler is about 30-h.p., and I should Belfast. recommend you to use firegrates, say, 7ft. longfirebars in two lengths. Dead-plate from 15in. course. I should also incline the grate a little, so that the end of it nearest the bridge stood about 3in. lower than the front end. To carry the front end, as also the middle and back ends of the bars, I much prefer a simple piece of square-bar iron with the ends bent down-say, 3in. to 4in.-and these bent ends curved to fit the plate can easily become the doorframe, and the furnace-tube. This saves drilling any holes in the furnace, which I greatly object to. The deadbar that carries the one end of the first length of piece of tee-iron with the web cut away to allow firebars. Even better than the square bar is a of the ends being forged down to fit the tube. Don't have any holes drilled in the furnace.-SUNLIGHT. Memnon, July, 1864; Waterloo, Feb., 1864; Star, mals.-The following account of the method of to 16in. long, and the width of furnace of [44796.]-Calculating Live Weight of Anicalculating the weight of animals by the pen may be found useful to J. O'S." :-Rule 1: Multiply the square of the girth of the animal by the length, both in inches, and the product, multiplied by the decimal 07958, will give the content in cubic inches; which divide by 576, and the quotient is the weight of the animal in imperial stones of 14lb. length, both in inches, and divide the product by Rule 2: Multiply the square of the girth by the 7238, and the quotient is the weight in imperial stones. Rule 3: Multiply the square of the girth by the length, both in inches, and the product multiplied by the decimal 00013816, the product is the weight in imperial stones.-PHILODEMUS. Nov., 1860; St. Patrick, October, 1874; Tennyson, Nov., 1869; Roberts, July, 1864; Princess Alexandra, January, 1863; Thunderbolt, October, 1874; Firefly, February, 1865; Clyde, Feb., 1863; Sanspareil, January, 1866.-DIOMED. [44792.1-Tricycle.-You cannot do better than get a machine with from 40in. to 44in. wheels, of pocket will permit, a machine that drives both the open-front class most certainly; and if your large wheels. If you want to save expense, then you might have one with single drivers. But at the present moment I am awaiting the testing of the machine I mentioned at page 65, and which promises to be the best I have yet seen. I will, is soon as I have given it a practical test, cquaint you with the result. Next to this new machine, I should myself buy an open-fronted one [44805.]-Hot-water Heating. So far as I with either both or one of the large wheels driving, But although this is a very good rule, still, a wheel can see, your plan will do, with one or two exaccording to the amount I had to spend, with, of ceptions. Don't use the pipe from the tank T in course, back-steering wheels, say, 40in. to 44in, be of the class in which the chain is made with is, if the reduction of the width was balanced by the boiler, or, at least, do not connect it with the a pipe from the bottom of the coil direct back to and preferably chain driving-gear. But that must conjunction with the return from the coil. Carry inti-friction rollers. The brake is certainly best additional strength otherwise. The reduction of back flow from the tank until they reach the lowest m the drivers, either on the hubs with a steel brake and, or with spoon brakes acting on the tires. If ou are not over-strong muscularly, then have the wheels driven with level gears. That is, the treadle bait makes turn for turn with the driving-wheels. f fairly robust, then have your 40in. or 44in. heels geared up to equal 50in. But don't go over hat, or you will find that at hill-riding it will erribly tell against you. Therefore, for easy nding at a slight loss of speed, try 40in. wheels, level geared. I myself much prefer the chain to the intermediate wheel for the drivers, although there is a wheel lately introduced that is likely to lo good work. There is one point more I would nention that makers do not appear to consider. It s to have your back-wheel not less than 18in. n diameter, and 20in. to 22in. is better still. ride with 20in., and it gives a command and traightness of steering that the smaller wheel fails afford. For ease in riding, adjust the seat well orward. But do not too much reduce the weight on the back-wheel, or you will find that the steering s not so certain. Such a machine as you describe would suit you well.-SUNLIGHT. [44793.)-Rook's Tables of Cost and Proat.-"One Who Had to Leave School at Eight Years of Age" should notice the heading of the different columns in Mr. Rook's book. If he wants o put on 27 per cent. to the cost price, he will ind the amount in the third column. If he wishes o have 271 per cent. of the money received from ny transaction as profit, he will find it the ourth column. The rule for this fourth column as follows:-As 100 less the rate per cent. is to 00, so is the amount given to the amount required -and in the case he gives, may be stated thus: As 72 100: 10s. 13s. 91d. Il business men should calculate their profit on he return of the money, and not on the cost price, cause there is no profit realised until the merhant has got the money safely into his pocket gain. Then, and not till then, he calls this amount r the purposes of his proportion 100-out of the oney he has to replace the capital originally insted-and the remainder is profit. Hence, whilst spital may return over 100 per cent.. a business ever can return 100 per cent.-G. HIRST, Whitby. 44793.1-Rook's Tables of Cost and Profit. -The "Return" column may be found by mulplying the cost by the rate per cent., and dividing 100, less the rate per cent. Thus, in the example ven, multiply 108. by 27, and divide by 72 (that 100-275), and the result will be 3s. 94d., which, ded to the cost 108., gives the figures in fourth lumn. This may be simplified by being turned to a vulgar fraction, and then reduced 5 11 5 29 = = should have a hub 6in. to 7in. between the spokes. space would not matter as long as you ran on good [44799.]-Erecting Small Engine.-Let me [44800.]-Daniell's Battery.-The fault is not in your zinc-plate, nor is the deposit copper. I think you will find, if you know how to detect it, that the deposit is iron, which results from impure acid or bluestone. If you use sulphuric acid, it should be colourless, while that generally sold, especially at oilshops, is tinged with yellow, due to the presence of iron. Is your bluestone clear, or is the appearance somewhat dulled, and are the crystals free from a whitish incrustation?-S. G. O. [44800.]-Daniell's Battery.--The muddy deposit is a mixture of copper oxide and the impurities in the zinc. It is caused by the soaking through of copper sulphate into the porous pot with the zinc, and zinc sulphate forms, and metallic copper is thrown down in an impalpable powder, which quickly oxidises into the black copper oxide. It cannot be entirely prevented; a rather finer-grain porous pot may be necessary. Use a semi-saturated solution of zinc sulphate instead of dilute acid, much less waste from local action then ensues. ELECTRICAL. [44800.]-Copper Deposit.-Daniell's Battery.-The querist has some sulphuric acid that contains nitric acid and, perhaps, arsenic; buy the purest you can get of some wholesale druggist, and mind and mix the solution some time before using; that is, let it be quite cold before you put it in the porous cell. I was troubled in the same way, but I now test the suspected acid thus-put an equal quantity of pure sulphuric acid with it in a glass and then add carefully a concentrated solution of sulphate of iron; if any nitric acid be present, a black ring will form where the two liquids meet.AN ASSOCIATE OF THE SOCIETY OF TELEGRAPH ENGINEERS. [44801.]-Brass-Melting Furnace.-Crucibles for above are made of fireclay, or of a mixture of fireclay and plumbago; but if "Amateur Brassfounder" will write to Thomas Fletcher, Warrington, as per advt. on page vii. of this week's paper, he will receive valuable information as to small furnaces and crucibles. - A WOULD-BE PIPER. Let level of the boiler. The pipe from the tank C may [44806.] Jet-Working. Small chisels of ordinary shape are used in turning jet on a lathe. The action is more of a scrape than a distinct cut. A knife the size of a penknife, with the point bevelled off, and then set like a chisel is used in carving-jet. Jet is first polished on a revolving wooden wheel with rottenstone and water, and then finished off on a board covered with stout leather-often porpoise-hide-impregnated with rouge or lampblack, mixed with a very small quantity of oil.-G. H. WHITBY. [44807.]-Lighting. - Reflectors that would stop light going upwards and send it out towards the sides of the room might answer. Try a flat tin plate immediately over each burner, with a portion cut away for the escape of heated air and smoke, &c. have found such an arrangement increase the illumination of distant parts of a room. The effect could be tried with one burner first, the others being turned off.-J. BROWN, Belfast. [44809.]-Electricity for Light, Motive Power, and Heat.-The proposed plan would, no doubt, succeed provided the windmill was large enough, cheap enough, the house stout enough to carry it, and the dynamo willing to work with such an irregular motor. The above are, I think, all the conditions from the non-fulfilment of which difficulty may be expected.-J. BROWN, Belfast. [44810.]-Soldering.-Have you tried dipping the soldered work into hot water, with a little ammonia in it. When well dried, you will not be again troubled with the beads of fluid.-SUNLIGHT. [44811.]-Crank-Shaft.-I should first borrow a couple, if possible, of hydraulic jacks, then remove the cap of the bearing; block up the end of the shaft, lifting it with the jacks until clear of the bearing, so that the brass can be removed. It need not be lifted more than about 6in. to Sin. Having got the one end lifted, next lift the other end in the same way, well securing the shaft from rolling either way. Now fit the new brasses to the shaft and also to the plummer-block, and level at a time of the shaft into its place again, and the both of them up true. Next lower down one end job is done without much trouble and expense. Such a job would not give me any trouble, from the fact that there were no beams overhead to lift by. Anything further you may want to know I shall be happy to tell you.-SUNLIGHT. The information 274 721 Now multiply by 11 and divide by and the result will be the same as above. All [44801.] Brass-melting Furnace. Much other figures in this column under the different depends on the question, viz., the quantity of metal rcentages may be calculated in the same way, you want to run at a time, and whether you have ad some of them may be turned into very simple gas or not at hand. If you only want to melt, say, actions. For 5 per cent. add 1-19th, for 10 per 2 or 3lb. at a time, your best and cheapest way, in ut. add 1-9th, for 20 per cent. add, for 25 per my opinion, is to either buy or (I do not know at add, and for 33 add 1. Some years ago I whether it is fair to Mr. Fletcher to say this) ew a large wholesale firm who invoiced a certain make an injector furnace of that gentleman's of goods at cost price with 10 per cent added, pattern. If you have not got a gas supply, then it d as a large trade was done with little risk or is a question of the maximum quantity of metal you uble, they, at settlement, gave 7 per cent. die-would want to run. I would then describe a new 44814.]-Lathe. The small wheel, or rather ant. They supposed they had a clear 2 per class of furnace to do the same in. The metal speed on the mandril, must be according to the [44813.]-Kindergarten. that "India" asks for on this subject would occupy more space than it is likely the Editor would grant; but it will be found in a tolerably concise form in a 6d. pamphlet entitled "How the Human Plants are trained in a Kindergarten," lately published by Messrs. Sonnenschein and Allen, Paternoster square.-BLANKENBERG. class of work you are going to do. You do not nches from the fire and keep the pan moving with say the height of the lathe-centre. With a fly-a circular motion, to keep the contents from wheel of 24in. diam. the pulley on the mandril burning to the bottom. Go on thus till it becomes for wood-turning should be from 3in. to 3 in. dia- as black as Spanish-juice. Now put to cool for ten meter; but for brass or soft metal it should be minutes, then add one teacup hot water and larger, as it would drive too fast. For wrought- simmer till all is redissolved. When cold, bottle iron, even of small diameter, you would require to for use.-OSBOL-DESTON. still further reduce the speed, and for cast iron you would want back-gear to do anything with. Each class of work requires a different speed; soft wood the highest, cast-iron the slowest.-SUN LIGHT. [44817.]-Speed of Pump.-If a lift pump is driven fast the barrel does not fill. I should consider that a 5in. pump with 24in. stroke should not be driven over more than 30 to 35 strokes per minute at the outside, as that would give at least 120ft. of piston (or rather bucket) speed per minute, and that is quite enough. Therefore, the length of stroke you name would be the outside when coupled with the speed quoted. Is the above the information you desire?-SUNLIGHT. [44821.]-Clarifying Temperance Drinks. Light and Bright' "will advertise his address, I can assist him in this matter. I have had a good deal of experience in this business.-R. B. [44823.]-Inhaler.-To G. H. WILKINSON."M. R." has no need to change the camphor [44826.]-Transparent Decorations. Use tracing-cloth for your screen, and paint your design with transparent oil-colours. Perhaps it would answer your purpose to place the screen in front of a window. Have the window open and exhibit a design on the screen by the aid of a good magic-lantern. You could have a slide specially painted, and, by the use of a powerful lime-light with the lantern, produce an illumination far superior to the method which you propose.-G. FRYER, Swansea. [44826.] - - In Transparent Decorations. reply to "G. D.," some years ago my father and myself made some very pretty transparencies in the following manner :-We got some good stout Bristol board (a species of cardboard), and cut the designs out with a sharp penknife. I think there were were two, one for each window, and as we were neither of us good draughtsmen we transferred the outlines with carbon paper. One was the royal Crown and motto and the other the Prince of Wales plume and motto. We then procured a couple of steel punches, and made two borders round the outside of each square, after which we painted the cardboard back and front with lamp, black and size, to prevent any light showing through. The various parts of the design we covered at the back with tissue paper of the proper colours, as, for instance, white for the plumes of the Prince of Wales crest and crimson for the Royal Crown. The two borders of round holes were of various colours, and after the whole of the designs, &c., were covered with tissue-paper over with a solution of gum-arabic. Altogether they were made semi-transparent by being painted QUERIES. [44831.]-Strength of Boiler-Plates - Wou "Sunlight" kindly give the rule for calculating a bursting pressure of different thicknesses of boiler-plas and the safe working pressure of the same-a rule wit example showing the relative diameters and thickness of plates to the bursting pressure -Joux Walere, [44832.]-Heating Small Greenhouse.-W any of your readers kindly inform me the best way heat a small greenhouse which is built close up to ind kitchen wall, on the other side of which we have a burning all day! I should be glad to know how to unle the heat from same, it being an old open grate with ore and boiler.-T. SHARRATT. [44833.]-Logarithms.-Will some of your reale oblige me with the authors and publishers incivi Young's Essay) on the computation of logarith with the most extensive tables that are publishe S. E. D. 144834.1-Division Plate and Fan-Blowers Will any correspondent kindly inform me where with driving-bolt, which connects cone-pulley with a division plate should be placed that it may not intere wheel on lathe-spindle? Also, what prevents & blowing-fan working, some fans of amateur ma merely churning the air without blowing properly? MAMMOTH. on the side of the [44535.]-Bleeding.-To DR. EDMUNDS.- Seeing you kindness in answering several correspondents, I bar taken the liberty of asking if you would give me al From a child I have been subject to excessive blee from the nose, seldom stops unless plugged or I falut attribute the commencement to a fall which caused b wound head. every local advice, and three physicians in London, d I have t each prescription has stopped the bleeding for 3 and kept my head constantly cool with cold-water bat night and morning, and thus prevented bleeding in the nose for a month or two, I have then frequ bled from the bowels. I am always trying or taki something. I am 30, eat no meat, total abstainer, minia -H. C. but it has soon returned. If I have been extra care order for small trowels 7in. long, 14in. wide, and fl 144836.]-Hardening Trowels.-I have a lar water at all, if he puts into the bottle a few pieces the tout ensemble was very good, and those not in thick. I find great difficulty in hardening them, a of camphor; without doing so the strength soon begins to diminish. I hope "M. R." will continue the use of the inhaler, and I have no fear but that he will derive ultimate benefit from it. Another very good plan of inhaling camphorated air, and one, too, that in construction is rendered portable, is to get a small piece of quill, say, about one and a half to 2in. long, open at both ends, stop one end with a small bit of cork, fill the tube with angular bits of camphor, stop the other end with another bit of cork, the corks should have a hole or a piece cut out of their sides, to allow air to pass through. The mode of using it is to place the end in the mouth and breathe through it; it looks very like an ordinary toothpick, which many people are in the habit of keeping in their mouths for a length of time together. I know of a gentleman in Liverpool who declared to me that by means of this simple apparatus he had warded off an attack of severe bronchitis which threatened to become chronic.-G. H. WILKINSON. the secret had no idea how cheaply it had been done. Possibly it would be an improvement if coloured gelatine were used instead of tissue-paper, as it would intercept less light.-ENCORE SANS PEUR. [44830.]-L. and N. W. R. Engines.-The following passenger-engines are at Camden-viz., 2183 Antelope, 2184 Reynard, 2191 Snowdon, 2192 Caradoc, 2194 Cambrian, 870 Fairbairn, 871 Proserpine, and 872 Wizard, all "Precedents." Also the "large Bloomers," 887 Knowsley, 889 Camilla, 891 Duke, 994 Ariel, 998 Una, and 1003 Tamerlane. There are also the Euston and Camden shunting-tanks, some six coupled saddle tanks that work goods over the N. L. R. to the docks, one or two of Webb's new side-tanks, and a lot of goods engines. Sorry I can give no information as to the other sheds.-W. B. P. UNANSWERED QUERIES. The numbers and titles of queries which remain unanswered for five weeks are inserted in this list, and if still unanswered 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. E. Stretton to 44364. Arranging Pianoforte Music for Full Band or 44242. Undulatory Theory of Light and Heat, p. 484. 44244. 44245. Orchestra, 484. 44247. 44252. L.B. and S.C.R. Engines, 484. 44255. [44824.]-Photography. The following are two methods by which a high glaze may be imparted to photographs without the aid of a rolling-press. 1. Take a clean sheet of glass-preferably patent plate; rub it over with a little beeswax dissolved in methylated ether, so as to leave a thin film of wax imperceptible to the eye; coat with plain collodion, wash until all greasiness has disappeared, flood with a dilute solution of gelatine, lay the print or prints carefully down upon it, squeeze to remove all surplus gelatine and chance air-bubbles, allow to dry, then strip and mount. 2. Mount the prints in the usual way, size with a clean solution of gelatine, say, gelatine 20gr., water loz.; allow to dry, and then coat with mastic varnish, which, for this purpose, may be conveniently diluted with 44253. an equal bulk of turpentine. An ordinary copying-44362. press is not of much use, except to keep the prints 44263. flat after mounting; but too much pressure must not be applied, or the prints will not dry. Put them face to face with a sheet of blotting-paper between to absorb moisture and prevent sticking. The time of exposure does not depend upon the size of plate or image, but upon the proportion of aperture to focal length. In order to take the large head, you would necessarily bring the camera much nearer the sitter; the conjugate focus of the lens being correspondingly lengthened, and the time of exposure increased. You cannot, however, fairly expect 44514. a 4-plate lens to cover a 4-plate properly. If you work in the open air and have a good light, you would probably succeed better by using the front lens alone. See my replies to queries 44008, 223, and 582.-PHOTOS. [44825.]-Colouring Water.-If W. Law will use burnt-sugar colouring he will find it to answer his purpose; this is what spirit-merchants use. you get good burnt sugar it will leave no deposit. R. B. If [44825.] Colouring Water. In an iron saucepan that will hold, say, one quart, put two tablespoons water and 4lb. loaf-sugar; gently boil till it begins to turn dark. Now lift the pan a few Curious Splashing, 454. Dental Electric Engine, 484. Union of Lancashire and Cheshire Institutes, 485. Overhead Motion Pulleys, 481. 44281. Gold Pellets, 485. 44291. 44295. the Manufacture of Bread or Cake, p. 581. Perambulator, Folding, 581. Ferret, 581. Paper-Making, 581. Scrap-Book, 582. 44536. Tangent Galvanometer, 582. Waterproof, 582. 44540. 44543. Getting on in the World, 582. University College, Bristol.-We have received the calendar for the sixth Session of University College, Bristol. It shows a course of lectures extending over all, or nearly all, the chief branches of a liberal and scientific education. Special attention has been paid to its chemical and engineering departments. Each of them in its own way combines theoretical with practical instruction. when I dip them in the water, they bend all forms. Ar information on keeping them straight will be grateful received by-COUNTRY BLACKSMITH. maker-Will you please say if a balance tool [44837.]- To "Seconds' Practical Watch pump-centre is a tool of any utility to a jobber who t not got a mandril? If so, say what kind of work cant done on one? WOBANG. Are the uprighting tools useful? nitrate of silver 2dr., ammonia spirit 3dr., dist [44838.]-Hair-Dyes. The following hair dy water 10z., I have tried with good effect to the be but fear that nitrate of silver injures. Will anyo recommend a safe preparation? The following is s not to hurt: hydrosulphuret of ammonia 1oz., potas solution 3dr., distilled water 1oz.; to be used as a application. When dried, apply: nitrate of silver lar ever, intolerable. A nutgall preparation is sold, b distilled water 2oz. The stench and pungency are, how question whether it does not contain the objectioned silver nitrate. Has anyone tried pure nutgalls! H "Walnut Pomade" been found of use for grey beard Lastly, I find it next to impossible to stain the rootst the hair with my dye, but have touched them w Bond's Marking Ink, which seems to have little effec B. C. Z. [44839.]-Electrical Contact, Motor, &c-C "Sunlight," Mr. Lancaster, or any one tell me if the is any reason why nickel, which is near y as hard as and does not oxidise readily, should not be used for dis trical contacts? Also, can they help me as follows! wish to make a small electric motor to work a 3in. cett fugal fan for blowpipe work at about 1,500 revolutions minute. I should like it to be on the same axle if pa sible. Would one like that described two numbers ba How much wire would be required on each magnet; ha do, or would one more like Froment's engine be be many magnets? What battery power? Any assista sketch if possible, would much oblige.-ОMEGA. [44840.]-Swan's Electric Lights.-How Bunsen cells would be required to keep one Swan burning?-OMEGA. [44841.]-Violin-Making. - To "FIDDLER."you ever try the following? Fiddle, ordinary shape, instead of f-holes a in. slit down centre of belly f end to end. The bridge would straddle the slit anda the two free edges. Of course, the belly must be thicke -C. P. T. [44842.]-Paper-Staining.-What will prevent l from putrefying when mixed with colours for have to be kept a fortnight, and is in a very liquid sta staining and yet not spoil the colours? The mixture -C. L. B. [44843.]-Paper Type.-In common, I dare say, many other readers of the ENGLISH MECHANIC, I like to know something of the paper-type process, principally for music. It is said to be much che than other processes, and if that is so, then no domá will become popular.-W. J. C. [41844.]-Reed-Organ.-I am constructing an on the suction principle, with 23 sets of reeds, but get them to speak quickly. I am almost sure the 12 are in. deep at CC, to at top C; all the notes lies in the channelling. As I have them at present, key on same channel, all the channels same le should I have them divided? Kindly give the pr length and depth of channels and length of pallet for one row of broad reeds, bent Sft. Turbans: 4ft., and row of celeste from Mid. C. I have s!! volumes except 23 and 24, but cannot get satisfactory formation. Also if they think the ordinary is a proved any on the suction principle.-BOMBARDOX. IT. 44845.1-Cleaning Lacquered Curtain Rods. Would any reader of the ENGLISH MECHANIC kindly lige by giving the best method for cleaning polished Ass curtain rods, which are lacquered, but have got ite covered by dust, &c., by lying by for some years, i the dust cannot be removed by any method known me without removing the lacquer. Could any of tell the best way of removing this ?-IGNO44846.]-Old Zinc Battery Rods.-Having over wt. of old zine battery rods which I wish to recast, after recasting a few I find them too brittle-can 7 of your readers give me a remedy for this defect?41847.)-Mathematical Works.-Will some of "mathematical readers kindly advise me what ks to read for the 4th stage examination of the nce and Art Department?- WALSDEN. 1STER. 44848]-Chemical Diffusion of Gases.-Disdation.-Does the rate of diffusion of gases vary 1 the temperature? If so, in what proportion? Can one recommend a cheap work which treats fully on sociation ?-WALSDEN. 949.1-Raising Flour.-Is it possible to lift from the bottom of a silk to a height of 20ft. by a m! If not, what size should belt and buckets be to 4 sacks per hour, the best place to receive and fer the flour? A sketch will oblige-DELTA. 4850]-Cooling Water from Condensing gine. Is it possible to cool the water from coner, which runs into reservoir and is used over again inually by a blast of air being put into the pipe by a able fan? A lift in this direction would be esteemed Four.-DELTA. movement to the armature. As partly shown in Fig. 2, FIC.2 4851.] Biscuits. Will some of your many TAUR. 44854.1-Hot-Bed.-As we are so unsuccessful with ordinary hot-beds, and as we require a steady heat some months, I am thinking of making a shallow e or galvanised iron tank, about 2 or 3in. deep and .by 3ft., filled with water and fitted with an exhaust It will be heated by a lamp underneath. Can of your correspondents kindly tell me if the water Ecirculate? If not, will it if I cant the tank a little I put the lamp at the lower end? If this design is not eticable, can someone suggest something better to LOS. 44855.1-Induction-Coil Peculiarity.-I have induction-coil containing 2lb. of 38 silk-covered wire, and in about 44 sections, between plates of paraffined ser. It gives with one 6in. Bunsen, a spark 1 in. long. I expected this coil to give a shock beyond Jurance, but in this it fails, the shock being comparaely weak. Does this indicate any defect, or is it on ount of the smallness of the wire? The coil is atinuous, as tested by a battery and galvanometer. E. F. [44856.]-Coins.-Will any of our readers kindly give s sorge information respecting the value as curiosities the undermentioned coins? 1 is a silver coin, rather rger than a shilling, Charles II., dated 1668. 2. Also Wer larger than a sixpence, William III., with a Nunder the head; both the above are in excellent ndition, and are much alike in appearance. 3 elieve is a coin (silver) of James II. with III., on the verse side, above which is a crown; there is also an ription round, but I cannot read it. 4 is a thin coin, on one side of which is a crown inside a globe thacross over the globe, all inclosed in ornamental order, inscription round it-GLVGKBESGHERTIST: IN: CEWERT, on the reverse side is the inscription TANNSKRAVWINGKEL: INNVRENBE (-): in the sarate are 3 crowns and 3 Fleurs-de-lis placed in a circle with a central flower. 5 is a coin, evidently of same ationality as No. 4, but older, as the figures are much ore coarsely drawn. The inscription is hardly legible, bat is different to inscription on No. 4, and the letters are larger.-BLUE DANUBE. [44857.]-Electric Engine.-I want to make one of about the same power as an ordinary model steam [44858.1-Options.- I have lately seen several advertisements recommending investors on the Stock Exchange to give their attention to the system known as "options," and I have examined some of the prospectuses which seem feasible enough, but should be glad to learn if they are bona fide or not. Do ordinary brokers, bankers, &c., make options a part of their business, or are they only dealt in by the more speculative portion of the Stock Exchange?-VENTNOR. [44859.]-Balancing of Locomotives.-Can any reader give me a formula for calculating the balance weights in locomotive engine wheels, and the angle which a line (drawn from the centre of driving-wheel to centre of gravity of balance weight) makes with the crank nearest to it ?-J. F. C. PANTAGRAPH. 19.99 [44869.]-Faulty Battery.-I have a two cell galvanic battery by "Stroud," which, after repeated trials, I have failed to get to work satisfactorily. Will any of "ours" kindly inform me the kind of acids to use?-hitherto I have simply used sulphuric acid and water, but as before stated, they have not had the desired effect. There are six brass pillars on the battery top, which I think don't connect properly with the cells; therefore, I shall be glad if a drawing can be given with the reply showing the proper connection of the cells with the pillars and the handles to the latter. Must all the wires used be of one thickness ?-CAPTAIN. [44870.1-Railway Rolling Stock.-I shall be glad if any of my fellow-readers would kindly enlighten me on the following:-I wish to know how the length of the wheel base is ascertained when building carriages, wagons, &c.? That is, the wheel base "centre to centre of journals," of a wagon 15ft. long is about 9ft. But how is this ascertained? A plain simple answer will greatly oblige-INGLEBORO. [44871.]-Steam-Engine Indicator.-I wish to make an indicator suitable to use with a condensing glad if someone will give me the necessary instruction engine. I am thinking of Richard's form, and shall be how to make one, specially with reference to the following points. 1. How is the piston packed? 2. What size steel wire must the spring be made of? 3. What special points must be considered in making it to work with a vacuum? 4. What dimensions had I better make the cylinder? Will someone kindly give me a sketch of the principal casting, with all dimensions?—AMATEUR. [44872.]-Waterproof Paint or Jak.-How is for coloured advertising bills? Could a medium (or vehicle) be made of shellac or resin ?-TICKETS. [44860.J-Leak in Iron Flue.-Could some fellow-waterproof ink or paint made as used by poster painters -DIOMED. [44862.]-Piano.-I bought a piano about 3 years ago at a sale of new pianos. It will not keep up to pitch, and now the pegs in the wood block wont hold; they have pulled holes in the block quite oval. What would be the best thing for me to do to cure it myself? HECTO. [44863.1-To" Sperans."-Will you kindly say how the property of a married woman would be legally disposed of who dies intestate during her husband's lifetime?-ANGLO INDIAN. [44864.]-I.M.E.-Will any reader kindly inform me the qualifications, etc., necessary to become a member of the Institute of Mechanical Engineers ?-ANGLO INDIAN. [44873.]-Steel Drops.-Could any of the readers of this able paper give me a receipt for removing from a tablecloth and carpet the stains occasioned by spilling a bottle of steel drops thereon? Soap and water has been tried without success.-MANA FORTE. [44874.]-To "Sperans."-Will you advise me? A. died in 1879 leaving £2,000, appointing B. and C. executors, and owing D. £20. C. died very soon after testator, and B. realised the estate. Repeated application is made to B. by D. for payment. B., then, after having got possession of testator's estate and owing to loss in his own business, goes into liquidation and his creditors discharge him. No notice has been taken of D. in the against B-W. business. Has D. any remedy in civil or criminal courts [44875.]-An Old Experiment by Faraday.An old but interesting experiment of Faraday's was the moved between the poles of a powerful electro magnet. resistance to motion and the heating of a copper plate Can anyone tell me whether the placing of the whole with the result?-F. M. apparatus in a perfect vacuum would have interfered [41876.]-G. E. R. Locos.-Would some corre- [44866.]-Phosphatic Manure.-I wish to test the DUNBOD. on?-COLUBER NAT. [44878.)-Microscopic.-(1) Can "F.R.M.S.," or [44867.)-Gilding.-I want to gild a deal panel and some strained paper. Will someone kindly inform me good lin. crank that I have got, and propose to do so used for attaching the leaf to them! When the leaf is to the way shown in the accompanying sketch. A is a of rocking beam fixed (at b) in bearings on bed- put on is it then sized all over? These gold panels piste (not shown), 4in. from centre at b to centre at c, propose to paint on in oil.-DEVONIENSIS. ain. between centres at c and d, which gives fin. [44868.]-Pitch of Screw.-Will any reader kindly cagine of 2in. piston diameter. I should like to utilise how the wood and the paper are prepared, and what is readers of the "E. M.," give their experience as to the I What objectives should I find the most useful? (3) capabilities of Zeiss' objectives for histological work? (2) Would a binocular or monocular be the best? (4) Have not Zeiss' lenses a greater working distance than Hartnack's?-A. B. C. 1:5053 144879.]-Secondary Battery.-Would one of ours kindly give me minute information respecting a Planté or Faure secondary battery, especially regarding the situation of the terminals! I want one that would, when fully charged, equal a quart Bunsen for about an hour.-ELECTRICIAN. [44880.1-Dew-Point.-To MR. W. J. LANCASTER, MR. CLEMENT WRAGGE, AND OTHERS.-Would either of the above gentlemen explain the effects (so to speak) of the dew-point? I have a complete set of meteorological instruments, excepting an anemometer, and know exactly how to find the dewpoint by Glaisher's tables; but what I want to know is this, What use is it in predicting weather when found, for I always conclude rain will fall when the two thermometers read nearly alike? Suppose the dry bulb 50, wet 46, the dewpoint then is about 42°. Would rain begin to fall if the dry bulb fell to 42° If that is so, it seems somewhat contrary to me, for, according to Deschanel, Ganot, Buchan, and others, if the temperature rises, dew is not deposited, whereas, the thermometer always rises before S.E, S., and S.W. winds, which are generally accompanied by heavy rains. The fullest explanation will oblige-M.M.I.Sc.S. [44881.]-Bath.-The bath as fixed in my house is made of zinc and painted on the inside. Hot and cold water are laid on. The expansion causes the paint to crack and peel off. Will any of "ours " tell me of a manner to mix the paint to prevent this, or a good substitute for paint? And, also, how to proceed to get the old paint off before repainting ?-C. F. A. [44882.]-Chemical Equations.-Will Mr. Allen, or any other gentleman, be so kind as to inform me, through the ENGLISH MECHANIC, the way to write chemical equations with one, two, or three salts, or acids and salts reacting on one another, with examples, and the "why and wherefore" of each ?-DUFFER. [44883.]-Naval and Merchant Services.-Will some reader kindly inform me the best course to adopt to train a youth for chief engineer on man-of-war or firstclass merchant steamer? What apprenticeships are necessary? What is probable cost of same? Is the above occupation cousidered a gentlemanly one?-PENE LOPE. 144884.]-Problem.-Can any of your readers assist to a solution of the following problem?-Given the triangle ABC, sides and angles all known, also the angles d and d1, made by the three points A B and C from D, whose position is not known. Find sides A D, BD, and C D, and other angles. The principle of the proposition is involved in an operation of surveying with the plane table, but I have never seen it explained. The position of D is found by construction, and can be accurately fixed by the angles as shown, and how the distances from A it to the other points can be calculated by trigonometry is beyond me.-Y. S. [44885.] To Canoeists Will an experienced canoeist give me a few hints as to the dimensions of a canoe which shall at the same time be a good sea-boat, capable of carrying plenty of sail, and pretty fast under paddle alone? Also, a few hints relative to description and dimension of sail found, from experience, to be the most handy and effective.-QAYIQJI. [44886.]-Siemens' Dynamo-Machine.-To MR. R. KENNEDY.-Would you kindly send sketch and a short description of the method of winding the wire on the field-magnets and armature of the above machine? I should like particulars of one with about 12in. field-magnets.-G. B. C., B. L. [44887.]-Instrument for the Measurement of Angles.-About a year ago I put a query in the columns of ours" as to the measurement of the sides of triangles when two angles and one side are known, and "F.R.A.S." gave a very clear explanation which enabled me to master what I could not comprehend by studying any of the modern books on trigonometry. I now wish to have advice as to the best means of measuring angles with tolerable accuracy and without going to the expense of a theodolite. I have tried a large semi-circular protractor, but find it very unsatisfactory.-EDINA. [44988.] L. and N. W. Engines. "DIOMED."-Many thanks for your reply. Perhaps you, To or someone, would further oblige me with the names and classes of Nos. 7, 97, 117, 222, 364. 479, 481, 626, 723, 802, 806, 896, 1158, 1372, 1519, 1528, 1672, and 1678.-W. B. P. [44889.1-Cane Blinds.-I wish to try to make a cane blind. Would anyone kindly tell what cane to use and how to bend it?-W. J. A. [44890.] Midland Engines.-Will any correspondent kindly furnish me in your next issue the particulars of the last Midland numbered 1470 to 1499 now running on the Southern passenger engines division, size and heating-surface of boilers and fireboxes, stroke of piston, diameter of cylinder, and size of wheels? Also, working pressure and weight of engine. -X. [44891.]-Turning Shafting.-Will "Sunlight" please describe the "box-centre" referred to in his reply, 44735, p. 73? Can I turn a shaft 18ft. long in my self-acting screw-cutting lathe, which will only admit 12ft. between centres? Can the work be as well done and as quickly, with the box-centre as between centres in the ordinary way! Please describe method of doing it. NO NAME. [44892] Connecting - Rod.-Will some reader kindly give a mathematical demonstration, with diagram, of the so-called "angularity" of the connectingrod, and formule for different lengths of rod, &c. 1J. F. M. [44893.]-Water v. Gas.-I wish to know which is the cheapest and most efficient motor for blowing an organ in a church. In the town I refer to, gas is fairly cheap and pure. The only drawback to a water-motor would be the frost, as the motor must be outside the building. experience with one or both motors. Any hints would Perhaps some of your readers have had oblige-J. F. M. [44894.]-L. and S.W.R. Bogie Engines.-Will some correspondent kindly give me dimensions of SouthSharp, Stewart, and Co. in 18771 They work the fast Western bogie engines like No. 355 and 367, built by trains between Salisbury and Plymouth.-E. W. J. obliged to "Sunlight" if he would kindly give a specifi 144895.1-Small Boiler.-I should be exceedingly cation of a Cornish boiler suitable for a 2 h.p. engine, and return him many thanks for his advice concerning Vertical Boilers in Brickwork. I may add I have plenty of room.-TIRED OF TURNING A CRANK. [44896.]-Paper -making.-What advantages are gained by using two slices" what is the difference between starch, farina, and the soon the machine! And, called paper-finish ?-O. soda ash is often quoted as so much per degree. What [44897.)-Chemical Calculation.-The price of is the meaning of this, and how can I calculate from it the price per ton ?-0. [44898.]-Jet-Exhauster.-Can any of your readers give an accurately dimensioned section of Smith's exhauster, stating greatest vacuum which can be ǝb(vacuum brake) or any other successful steam jettained with, say, 50lb., 75lb., 100lb., and 120lb. pressure? -L. [44899.]-Repairing Geneva Watch.-Will some reader kindly help me to put a new mainspring in a Geneva watch? I have unscrewed the bar and taken it mainspring inside) from the bar.-AMAteur. out, but am at a loss how to separate the barrel (with geological treatises that these concretions are designated [44900.] Septarian Nodules.-I find in old Ludi Helmontii. Will someone kindly tell me the meaning of this name?-L. CLAY. correspondent recommend a battery for an electric clock? I want one that will give a fairly strong current, and be [44901.]-Battery for Electric Clock.-Can any constant and require setting up less frequently than a Daniell.-ELECTRICAL. [44902.]-Reducing Oil of Vitriol.-Will some of your correspondents give me a rule for calculating the quantity of water required to reduce oil of vitriol of sp. gr. 1:350 to 1.370, or any higher sp. gr. to a lower one. The answer in plain figures.-TONNELIER. [44903.]-Model Loco.-I wish to make a model locomotive. Will some reader kindly inform me if the following dimensions will do?-Boiler, 12in. long, 4in. diameter, heated by spirit-lamp; single-action cylinders, 1in. bore, 2in. stroke; driving-wheels, 5in. diameter. Would double-action cylinders be better? And, if so, what size?-NOVICE. USEFUL AND SCIENTIFIC NOTES. A Visit Hospital. to the London Temperance (situated about three minutes' walk from the Gower "Of the Temperance Hospital, Street Station of the Underground Railway) I can chairman of an Infirmary Board of Management, only say, after an experience of twenty years as that anything more perfect than the arrangements of the building, the character of the nursing— carried on entirely by lady nurses-and the unmistakable religious tone which pervades the whole establishment, can hardly be conceived. This is quite irrespective of the speciality of the hospitalthe absence of alcoholic remedies in the treatment of disease. To anyone interested in hospital management, especially if they should have the good fortune (as I had) of being conducted through the wards by Dr. Edmunds, the Senior Physician, I can promise that a visit to the Temperance Hospital will afford a treat of no ordinary kind, and another evidence, if any were wanting, of the the efforts of all who are engaged in this great extent to which the blessing of God is resting upon work of national reform."-The Rev. Canon Ellison, M.A., Rector of Great Haseley, in the "Church of England Temperance Chronicle. bearing this name is now being exhibited in London The Molecular Telephone.-The telephone at 37, Walbrook, E.C. Its special feature is the sounds being produced in this instrument by one non-use of a detached metallic diaphragm, the pole of the magnet, of peculiar construction, resting upon, or rather in contact with, any substance not actually impervious to sound. examined the receiver, and tested it with plates and We have fragments of wood, glass, ebonite, and even of cork, of irregular shapes, and found the articulation excellent, the crucial test of sibillation being completely satisfactory. One practical advantage of this form of telephone is that it will bear rough usage, no nice adjustment of diaphragm to magnet as in the ordinary telephone being necessary.-The Electrician. ANSWERS TO CORRESPONDENTS. All communications should be addressed to the Editos of the ENGLISH MECHANIC, 31, Tavistock-street, Corat Garden, W.C. HINTS TO CORRESPONDENTS. 1. Write on one side of the paper only, and put drawtitles to queries, and when answering queries put the ings for illustrations on separate pieces of paper. 2. Put aumbers as well as the titles of the queries to which the replies refer. 3. No charge is made for inserting letters, queries, or replies. 4. Letters or queries asking for adsuch information, cannot be inserted except as advertise tools or other articles can be purchased, or replies ginag dresses of manufacturers or correspondents, or where ments. 5. No question asking for educational or scienti information is answered through the post. 6. Letter not forwarded; and the names of correspondents are not sent to correspondents, under cover to the Editor, re given to inquirers. ... Attention is especially drawn to hint No. 4. The space devoted to letters, queries, and replies is meant for the general good, and it is not fair to occupy it with ques tions such as are indicated above, which are only of indiselves, lead to rcplies which are. The "Sixpenny Be vidual interest, and which, if not advertisements in themColumn" offers a cheap means of obtaining such infor The following are the initials, &c., of letters to hand up mation, and we trust our readers will avail themselves of it to Wednesday evening, Sept. 28, and unacknowledged elsewhere: HILLMAN, HERBERT, AND COOPER.-Rev. W. L. Pendered -J. H. Makin.-A. H. Fison.-John Noble.-J. C Frank.-Foster Bros.-H. Palmer.-Rev. W. C. Brace -F. Shelley.-E. C. Rothзram, -R. H. Blyth.Ball.-Gordon Salt.-Boyd Moss.-Cosmorama.-W. J. Barker.-F. W. W.-C. C., Uxbridge.-Country Lad.-Aconite.-Novice.-A. W. K.-M.I.C.E.-B. E -Keraulophon.-T. G. A.-J. H. M.-El Capitan -J Hale.-T. B.-Sufferer.-Working Tom.-R. CrownGas Bath.-C. P. T.-Murano. - Young Ireland.-XW. H. B., Bradford.-Hard Up.-J. F. E.-W. Gras ger.-G. H. Wilkinson.-Darkey.-Poor Man.-Pl Almoni.-Cotswold.-Engineer.-A Young SmithWm. Allen.-F. H. Wenham.-J. Brown, BelfastH. M.-Crankshaft.-T. Stone.-Set Rod -Spe Salvo.-F. D.-M. R.-Old Thumper.-W. RichardsIndia. SCOTLAND. (We know of no book on the subject, ba there are articles in the cyclopædias, and in such work as Watts's "Chemical Technology.")-WAB. (To do not repeat the query, and we cannot remember it. J. REYNOLDS. (We do not know, but should ima not.)-F. YELWOC. (You should procure Proctor's "Half-Hours with the Telescope" or Webb's "Cl tial Objects for Common Telescopes." A 3in. is a good size, but a 2in., with a first-class o.g., is quite lar enough for a beginner. See many places in bac volumes.)-GEORG FENWICK. (See any book on As tronomy, or p. 12 of the number for Sept. 9.)-J. J. C (There are Lardner's "Rudimentary Treatise on the Steam Engine," Baker's "Steam-engine," with rulet and examples for practical men, and Steam and the Steam Engine," by Sewell and Clarke, all pab lished by Lockwood and Co., Stationer's Hall-cour E.C.)-REFLECTION. (Balmain's luminous paint is See p. 471, Vol. XXX.; p. 77, Vol. XXXI., and other places in the last three volumes.)-J. F. (Try Mr French, 89, Strand, W.C.)-WM. PETERKIN. (Sump' soaking, with an occasional shake. Water boiled filtered will do. A wineglassful.) GEO. WH-0 (Answered on p. 76)-MINERAL OIL. (Don't you th such a recipe would be commercially valuable! W believe something can be done with camphor, bergam and other scents to mask the odour. See p. 575, N 595, for a patent process.)-P. NUTTALL. We have given plenty of recipes for "graph" processes. pp. 20, 159, 170, 189, 241, 479, Vol. XXX., and p. 545 Vol. XXIX.)-STAMPER. (Heat it. If you mean in rubber stamps, sulphur is mixed with it.)-A Groves NESS. (Not easy, but oxalic acid, strong solution bo ing hot, will discharge the ink, and weak solution o chloride of lime will bleach the paper. Use hot wat and blotting paper to wash the oxalate out. With little practice you may obtain good results, but we s pect you will have to tint the paper.)-AQUATIC. indices of back volumes, and get Fletcher's, of War rington, catalogue.)-JOHN STEELE. (Mastic vari See p. 538, No. 776.)-HYDROGEN. (There is a bonaseller of that name at 69, Ludgate-hill, E.C.)-Cas WAY. (We answered you some time ago. It is a quem tion for a surgeon. The operation is very simple ARITHMETICAL IGNORAMUS. (Yes, that is correctnear enough.)-MOBLEY BOB. (Datum means some thing given; in the case in question a line, as a sea-level, from which to measure altitudes.)-BOEKINO CORK. (Water in a steam-boiler at a pressure of has a temperature of rather more than 400 FahrF. W. (See answer to "J. J. C." above.)-McLAURA (See the instructions for making similar machines recent volumes. How can any one say whether you a clever enough to make it, or tell you the approxim cost when no size is mentioned ?)-ALF. ILLINGWORT ("Electricity," by Sir W. Snow Harris, Lockwood o Co., Stationers' Hall court, E.C., 1s. 6d., is a good boo on the principles, but we suspect you want to know how to construct the machines. There is no book of the kind.)-OUT OF WORK. (The aniline dyes are the plest. A good process for black was given on p. 1 and there are many recipes in back volumes.)-FEL (To answer such a question would be invidious, but probably Dixon's, with his book, would suit you -M. C. P. (Bisulphide of carbon, or mineral naphtha Shred the rubber fine, and shake occasionally GOLD. (Answered a few weeks ago. See the index published with the last number.)-GAUGE. (See p. 6 last volume.)-W. J. F. (Not if it is of any use as a conductor.) -PHILODEMUS. (Longmans, we believe) DARKEY. (See indices for descriptions of Bunsen ba tery. At least 30 quart cells would be required)-J\\\ SANDHAM. (London, of course.)-T. RILEY. (We d not know, but possibly M. Detaille, or some of o other French correspondents, might notice, and reply to an advertisement in our own "Address" column.) best The English Mechanic AND WORLD OF SCIENCE AND ART. FRIDAY, OCTOBER 7, 1881. SPIRAL APPARATUS. By J. H. EVANS, THE last specimen of turning illustrated being that of spiral work, I propose following on with a description of the apparatus, and as it is an adjunct easily added to any lathe worthy of it, I consider the illustrations will be of considerable value to many. I intend, in the first place, to show the apparatus in its original form, or rather, as it is generally adapted, and later on I will illustrate the various improvements I or pinion, according to the pitch required, on Fig. 1, working in the slot, seen distinctly All the work upon which spirals are to be cut, must, of course, be screwed on to the nose of spiral chuck, which is, of course, a fac-simile of the mandril-nose, and consequently all the chucks belonging to the lathe will go upon the spiral chuck. In working, however, it will be necessary to come to the permanent arbor, Fig. 6; the object of this is to change the direction of the screw or spiral from a right to left-hand have added to it. Before alluding to the turn the work in its place on the spiral figures on the engravings, I think a short chuck, because, if it is turned on the mandrildescription of the actual machinery, so to nose and then placed upon the chuck, it speak, will be advantageous, especially to will not be absolutely true, unless a transfer that is to say, reverse the direction of the the uninitiated in this particular branch of chuck be used in the first instance; these slide-rest screw as compared with that of turning, which in workshop parlance is we shall come to anon. To proceed, there are the mandril. For example, three wheels screw-cutting; but, as adapted to orna- 16 wheels and pinions, and to give the will cut a right-hand screw, four a leftmental turning, the productions are termed numbers will be sufficient without occupy-hand, and so on. I intend to give a table of Elizabethan twists. First then, the apparatus ing space with illustrations of all; the settings when this apparatus is completed, consists of a train of wheels, which form a numbers will be 144, 120, 96, 72, 60 (two), but I may mention that it must be fully connection between the lathe-mandril and 53, 50, 48, 36, 24, 20, 18, 16, 15, and on understood that the main screw of the slidethe main screw of the slide-rest,' and it will the permanent arbor a pinion of 30 teeth. rest should be no other than 10 threads to be seen at once that one cannot be moved These 16 wheels and pinions comprise the inch. The arbor, it will be seen, can be without the other; consequently, to divide the whole set in its present form, and are moved to any part of the radial arm when the work into different parts, it will be considered quite sufficient for all practical fitted to the straight slot F, Fig. 1, and will obvious that the pulley will be useless, there- purposes, inasmuch as the coarsest combina-admit of any possible change being made; fore, what is termed the spiral chuck, must tion of the arrangement can be made to pro- and it is by this means that the various be substituted; this chuck is fitted on to the duce one turn in seven inches, and the finest wheels employed are connected to the spiral nose of the mandril, and in front a revolving 320 threads to the inch, the latter being chuck and slide-rest. In most cases only ratchet-wheel, with 96 teeth and detent, is sufficient to form simply a smooth cut over fitted. As before stated, I am describing the a cylinder. An infinite variety between apparatus in its original form, my principal these two may, of course, be obtained. object being to show the improvements in the arrangement I now make. On the back of the chuck is a fitting on which any of the change-wheels can be placed, and in working with it one of the wheels must be on the chuck, and that gearing into another wheel VOL. XXXIV.-NO. 863. The radial arm A, Fig. 1, is fixed to the headstock by means of the screw B, Fig. 2, which passes through the circular slot C, Fig. 1, and having a thin steel washer under the head, it holds the arm in its place without extreme pressure. The circular ring D, one intermediate wheel is used, employing the single arbor only and the three wheels all in one plane, consequently the spiral produced will depend upon what I may term the two main wheels-viz., those on the spiral chuck and slide-rest screw; for instance, if both are of the same number of teeth, the mandril and slide-rest screw will turn equally, or turn for turn, |