UNANSWERED QUERIES. We trust Since our last C. R. M. has replied to 43383; F. Barker Cooke, 45263, 45308; A. W. Soward, 45308, 45552; An Old Subscriber, 45552. make into a stiff paste with strong gum-water. [45909.]-Oxygen and Hydrogen.-OxygenI tried these, but found them very friable. gas, whether it is obtained from the red oxide of Subsequently I tried two other plans. One was to mercury, from chlorate of potash and manganese, strongly compress the paste as above into pieces of and any other bodies, is one and the same gas, and The numbers and titles of queries which remain unanbrass or tin tube. Tin will do if the joint is folded. is, therefore, just as well suited for lime-light pur-swered for five weeks are inserted in this list, and if still What was neatest was short pieces or sections of purposes. In all cases it is best to pass the unanswered are repeated four weeks afterwards. drawn brass tube, cut to the length of a lime oxygen through a wash bottle, and if the our readers will look over the list and send what information cylinder. Then compress into it the pasty mass, water is saturated with caustic soda, so much they can for the benefit of their fellow contributors. and pierce a hole for the lime pillar. Next, well the better, as the chlorine gas evolved is thereby dry in an oven, and see that the heat is kept up absorbed. By this the light is increased, as the until the cylinder is dry throughout. Now examine chlorine, which would otherwise have been carried the tube, and placing the joint on the tube at the over with the oxygen considerably reduces the reverse side to the jet, expose it to the hydrogen light; therefore the abstraction of it is a decided flame first and get warm. On turning on the gain. Add to this that chlorine gas is most deoxygen-gas the heat quickly fuses through the structive to the gas-bags and we have another brass shell, and impinging on to the mass behind reason for wishing to eliminate it. We might dry a good light results. Without the metal case the the oxygen by passing it through a drying tube, cylinders are apt to wear away by the expansion, but that would be needless for general purposes. chipping off corners and the outside parts. Slaked It would be considerably cheaper to use sulphuric or powdered lime is no good, as the lime once than hydrochloric acid for the production of hydrohaving absorbed water you can do nothing with it. gen, as you would soon find out if you tried it in Try this and let me know how you succeed. It practice.-SUNLIGHT. will not be as good as a proper lime cylinder, but will be found a fair substitute.-SUNLIGHT. [45905.]-Tests for Air and Water. The impurities occurring in air and water are usually present in such minute quantities as to require chemical analysis to detect and estimate them. A detailed description of these processes would occupy far more space than is usually devoted to replies to queries. I must, therefore, refer the querist to such works as Fresenius' "Quantative Analysis," Bunsen's "Gasometry," and Wanklyn and Chap man's "Water Analysis" for information. If, however, "H. S." simply requires a few qualitative tests, I will do my best to help him. The most accurate method for determining the hygrometric condition of air, is to aspirate a known volume (10 litres) through a weighed U-tube containing pumice saturated with strong sulphuric acid. The tube being weighed after the experiment, will show by its increase in weight the quantity of aqueous vapour in the 10 litres of air. some of the most delicate and refined methods of ANALYST. 45358. 45349. 45384. 45105. Sulphate of Strontium, 290. Velocity of Water in Sewers, p. 387. 45579. Metallurgical, 387. 45569. 45606. 45617. To "L. W." and "W. L.," 387. Chatterton's Compound, 357. QUERIES. [45916.1-Launch.-Many thanks ty"Sunlight" for his kind offer. In the "Address Column" last week will be quite large enough, for I cannot now change it. In reply [45909.] Oxygen and Hydrogen. - The 45591. source of the oxygen used for lime-light purposes is of no consequence, provided the gas be pure. It 45618. is merely a matter of convenience and expense. 45620. If H. Richards desires to try the chloride of lime method, he should make a thick paste of bleachingand, to prevent frothing, a small quantity of powder, add a little solution of cobalt chloride, paraffin oil. This mixture he should heat to between 70° and 80° C. The gas, before being collected, may be passed through a wash-bottle containing water. The object of a "wash-bottle" is to remove any traces of soluble gas, and to retain any solid matter mechanically carried over. Thus, in the preparation of oxygen by the usual method (by heating oxide of manganese and chlorate of potash), small quantities of chlorine and of carbonic acid gases are evolved. These are contained therein be rendered slightly alkaline. In stopped by the wash-bottle, especially if the liquid the preparation of hydrogen it is more economical to use sulphuric than hydrochloric acid. For although 31b. of the latter will go as far as 4lb. of the former, still as, roughly speaking, commercial [45917.)-Launch-I hope this will be seen by muriatic acid contains but one-third its weight of "Sunlight" before he has replied to mine of last week. pure acid (the residue being water in which the Since writing before, I have about decided to make my gas is dissolved), whilst oil of vitriol is practically launch 23 or 25ft. long, fearing 20ft. will not be very without water; it is evident that about 91b. of another of same size, or I could get up new castings, as, satisfactory To my present 4 by 5 cylinder I could add hydrochloric acid, as met with in the market, so far, I have nothing but the castings. Would two cylinare equivalent to the 4lb. of sulphuric acid. If ders 4 by 5 be too much power! or, if you advise another these figures are multiplied by the respective set of single-cylinder castings, please give dimensions; I prices of the two acids, it is seen that the first-prefer horizontal boiler. Please give me measurements of named is about five times as expensive as the second.-ALFRED W. SOWARD. [45905.]-Tests for Air and Water.-Most of the impurities in air are from organic matters in the state of putrefaction, and can be generally recognised by the nose. Of other impurities the chief is carbonic acid gas, of which there ought never to be more than 04 per cent. To see if this is the case, you only need a 10oz. bottle with glass stopper, and some lime-water. Having filled the bottle (by moving it about) in the air, you then add about a tablespoonful of lime-water, and then place the stopper in and shake it; if it does not become cloudy, the amount of carbonic acid gas is less than 04 per cent., and, therefore, not [45910.] Ink for Sketching on Terradangerous. Tests for impurities in water: The Cotta.-Try Brunswick or Japan black. Thin most common and dangerous impurities are from with a little turpentine if necessary.-J. KENDALL. organic matter and lead. First, then, to test for organic matter, add some dilute oil or vitriol to the [45912.]-Mathematical.-If a vulgar fraction water, and then some Condy's disinfecting fluid has a finite square root, the numerator and de(potassium permanganate), which is diluted with nominator of the fraction will be exact squares, ten parts of water to one. If much has to be when the fraction is reduced to its lowest terms. added, it shows that the water has some organic In the examples given in this query, 343/1183 has matter in it, and is, therefore, unfit for drinking. a finite square root, as when reduced to its lowest The other impurity (lead) can be tested for by add-terms it becomes 49/169, the square root of which ing some hydrosulphuric acid to the water, and, if it is 7/13; the next two examples have no fiuite becomes coloured, it shows that there may be some lead in it. I have not time to mention other impurities and tests, but these are the chief. To determine the hygrometrical state of air, you must have a table of the tensions of aqueous vapour.HG. results." found my address. I am sorry he does not consider my engine drive a boat up to 25ft. at fair speed; and it was on this to query 44607, he said a 4in. by 4in. cylinder should authority that I started the engine. I should be obliged for any suggestions from Sunlight" in addition to the plan (which he has kindly promised), sufficient for a need hardly add that I shall feel under a great obligation novice to get the right lines. Also, the address of a reto "Sunlight" for offering to communicate with me through the "Address Column "CANADIAN SUBSCRIBER, liable maker where I can get a horizontal boiler. [45919.1-Filtering Feed-water for Boilers.above subject? I have two 40-horse boilers fed from a Can any of your readers give me any information on the river, the water of which is at times very thick and muddy with silt or "warp," as it is called. I had square root, but the fourth has a finite square root, thought of putting down a long tank divided into com3 11. The algebraic expression given in the query partments, arranged as a labyrinth for the feed-wa'er to may be put in the form 17x (xy) (xy); the pass through, and so allow it to settle before pumping last factor is a cube, and in order to make the into boilers. I require about 600 gallons of water per hour. Can any of your correspondents suggest any filterwhole expression a perfect cube we must multiplying medium, or any better arrangement than the above? the remaining factors by their squares, therefore -FILTER. the required multiplier is 289 (x y)2.M.I.C.E. [45420.]-Audiphone.-Can any reader give me any information concerning an instrument called an audiconstructed of vulcanised indiarubber, made into the [45906.] Tests for Air and Water. "H. S." will do well to get Church's "Plain Words about Water" (Chapman and Hall). It costs but a few pence, and contains a lot of useful estimation of nitric acid in commercial nitrate of form of a ladies' fan, with silk corus running round the [45915.]-Nitrates.-The process given for the phone, for the assistance of hearing? I am told they are information. I am afraid that there are no "ready soda will only answer for nitrates of the alkali edge for the purpose of drawing it into a more or les methods of ascertaining the impurities in samples metals. For other nitrates, I prefer the following: concave form; and for the purpose of hearing is held of air and water, so as to obtain comparative Weigh out 0-5gram. of the sample into a tubulated between or against the teeth. I am given to understand Such results can only be obtained by retort, add about 100cc. of strong soda-lye (free that they are to be procured from a firm in Scotland, but careful analysis, the methods for conducting which from nitrates), and connect the retort with a bulb-whether it would be of any practical use to me as au the price is two guineas. Now as I do not know are to be found in the textbooks. If required, I tube containing 10cc. of normal acid solution. assistance to hearing public spek rs (really, the only will explain them; but this seems hardly the place Drop into the retort, through the tubulure, a few thing for which I should requir- it--being partially deaf). for anything so comprehensive. ALFRED W. SOWARD. strips of thin sheet aluminium, immediately replace I do not feel myself jus ified in laying out so much withthe stopper, and allow the whole to stand for a few out first putting it to the test. If auy reader who has [45909.]-Oxygen and Hydrogen.-Oxygen hours. The aluminium will gradually dissolve, seen or used one could give me any further hints as to the construction I have no doubt I could make one prepared from chloride of lime would certainly be with the evolution of hydrogen, which will com- sufficiently wel: to test their efficiency before buying a as effectual for limelight purposes as that prepared pletely reduce the nitric acid present to ammonia. more perfectly-made instrument. I may mention that it in the ordinary way, for oxygen is oxygen, from The contents of the retort are now heated to boil-cust the possessor of one 30s. to have one of the ribs whatever source it is obtained. I should not, how-ing for about an hour, so as to distil the whole of repaired, without which it was perfectly useless. Any inever, advise H. Richards to attempt to prepare it the ammonia into the standard acid. It now only formation will greatly oblige-C. H. A. B. from that source, as nothing would be gained remains to titrate the contents of the bulb-tube thereby, either in the way of convenience or with normal soda solution, so as to ascertain how economy. The use of the wash bottle is to arrest many cubic centimetres of the standard acid have any particles of the materials that may be carried been neutralised by ammonia, and to multiply this over mechanically from the retort; it is also useful number by 063, which will give the weight (in in showing the rapidity with which the gas is being grams) of nitric acid in 0.5 grams. of the sample. generated. Ordinary commercial sulphuric acid The above process is applicable to all nitrates, even will yield, when decomposed by zinc, more than when present in minute quantities, such as occur twice as much hydrogen as an equal weight of in samples of well-water, the ammonia in this case commercial hydrochloric acid, and as these acids being estimated by means of Nessler's reagent. are retailed at about the same price per pound, Nitrates may also be reduced to ammonia by the sulphuric acid evidently has the advantage in point copper-zinc couple; but I have not found it give of economy.-ANALYST. such good results as the above method.-ANALYST. [45922.]-Chrysoide.-There is an article of the above name made into harness furniture, buckles, &c. Will any reader kindly tell me what are the met als entering into its compos tion? and when used for the above purpose, what character has it obtained as to its wear, strength, ease to polish, and liability to tarnish, and is it well adapted to form harness furniture ?-ENQUIRER. [45923.]-Brazing Bicycle Forks in.-Will any of your numerous correspondents inform me of the best method of brazing bicycle forks in ?-ROBERT WIGHT. [45924.]-Lathe Chuck.-Will "Sunlight," or some reader of the "E. M.,' explain how to make an iron self-centring chuck for 6in. centre lathe? The jaws will not be required to move all at once. I require four jaws; can make it myself, as I am a-CARRIAGE SMITH. [45925.]-Model Multitubular Boiler.-Will "Sunlight," or some other gentleman, tell me how to make a model multitubular boiler, 12in. long, and 4in. diameter; how to create a draught, as it is to be stationary; and if soft solder will do for joints?-C. H. PHILLIPS. I am [45926.]-Bookedge Gilding.-When I have used the prepared glair, and laid on the gold leaf, I allow them to dry for a few hours. Then when I try to burnish them, I find the gold leaf come off. I previously scrape the edges, and the stone of the bu nisher is agate, so that these are not the causes of my failure. I should be obliged if any of your readers could tell me the cause, and so help me out of my difficulty.-R. NORBIS. [45927.]-Belgian Tank Engines. anxious to obtain particulars of the ten-wheel coupled tank engines used on the Belgian State railways, with a drawing if possible. Being of such an uncommon type, this would no doubt interest many other readers. haps the Flying Dutchinan" lection he mentioned in a former number.-GROSVENOS. can give one from the col[459281-Spherical Rest.-I have access spherical rest of foreign make, the worn-wheel of which feeds the tool up to its cut. Answers admirably for making billiard-balls, but it is useless for o namen at turning or drilling, as the number of teeth in it are not susceptible of division. It has 59 teeth, and is advanced one tooth at a time by a complete revolution of its taugent screw, which, therefore, drives it forward 1-59th part of the circle, or 6'10172. to fit changewheels to the tangent screw, so that one Will anyone say how I am complete turn of the driving-wheel will drive the tangent screw so much short of a comp ete revolution that it will move the worm-wheel exactly 1-16th of the circle.GERERE ADMI. to a [45929.]-Magneto-Electric Machine.-May I be allowed to inquire through your paper whether any of your readers have made a magneto-electro machine according to the description given by Mr. Cuttriss, Vol. XXX.. pp. 142, 188, 315, and if so, how it works? Or would Mr. Lancaster give an opinion on the same! If any report and opinion has beod already published since Vol. XXX., I should be quite sati-tied with a reference to it.-R. J. JONES. [45930.1-Cupola Work.-Will any of your readers kindly suggest the best possible means of preventing sparks flying from a cupola? I have two cupolas working alternately every week (about five feet apart) under a very strong pressure of bla-t, and, unfortunately, a timberyard is about 40 yards distance from them; and in the summer time there is great danger of a stray spark doing serious mischief.-J. L. [459311-Oboe.-To "VULCANITE."-I was much interested in your remarks in "ours" of 20th ult., and should be very glad if some information could be given as to the method of making an oboe. Also the kind of tools used, and the correct shape of the bore and especially the mode of tuning the instrument, that being the most difficult and critical part of the whole business. It would also be a great advantage if the best mode could be ascertained of correcting the intonation and tone of defective notes in an old oboe. Also, whether any method is known of restoring the bore when it has become worn out of shape, by lining with wood or otherwise? Is vulcanite & good matial for obees? answers in clarionets very well, I believe.-W. S. B. It [45932.1-Exhausting Large want to exhaust a arge cylinder, and I wish to appeal to Cylinder.-I some of your readers as regards the construction of an air-pump. I may say that I have got a special pump (Cameron's patent), if, by a little alteration, this would suit the purpose.-J. W. [45933.)-Legal.-To MR. WETHERFIELD.-A. and B. entered into partnership last August, entering upon premises to carry on business. They each paid in an equal sum of money, and each to receive half of all profits. There are no articles of partnership, nor any waiting whatsoever. They have a lease predated from May next for 4 years, and each are parties to it- -conjointly and severally. A. has proposed a disse lution, offering B. the alternative of Paying A. out, or A. will pay B. ont. B. can't raise the capital, and refu-es a dissolution on the ground that as he is a party to the lease, it is. sufficient evidence for him the co-partnership was intended for that period. landlord is willing to take either as tenant. The case The is in Scotl-nd. Does this come under the case of a "Part nership at Will"? Can A. force a dissolution? Is B.'s posi- F. I. D. [45035.1-Clarionet-Tuning.- I should be much obliged if Mr. Fryer would give a little more detailed description of the instrument he recommends for clarionet tuning on page 481, and say if he thinks it would be sufliciently accurate for laying the bearings of an organ. ANGULUS. [45936.]-Electro-Motor.-I have a machine of my own invention and make, which works at present by two levers, and I should like to work it by electricity-if possible. The object in this machine is to revolve a shaft with a number of brass wheels. I wish to set this shaft in motion and let it stop where it likes, and when stopped to be held in position by ratchet wheel and pawl. This I have on now, worked by lever No. 1. This lever at extreme end works about 1fin., and is released momentaily. No. 2 lever works about 4in., ani pulls at about 141b.-64 CRUSOE. [45937.)-Engine-Tubes.-I cannot keep the tubes of a nearly new portable engine which I have tight for shop, which has done a deal more work, gives no trouble. long together, although a sister engine from the same I have been forced to expand them twice in about 18 months. The engine has a bad firebox, the iron being [45939.1-Electro-plating-Will (45940.]-Beam Engines.-Will any fellow-reader chief expense is in crushing that up tine. The ore is toler- [45942.]-Compressing Gas. A friend of mine [45945-Expansion Link.-Would " [45946.]-Pumping Gas.-Would any of our pipe is in, diameter. I would like some practical infor- [45947.1-Condenser-To "SUNLIGHT," OR OTHERS, 145948.1-Nut Making.-Can this be done with tio on my copper-bits coming off after a few heatings, [45951.]-Shot - Making.-Will any of our kind [45952 -Intermediate Receiver.-I should like WETHERFIELD.-If an innkeeper has taken a license FER, 3, 1882, months? or, in other words, can two licenses be grate in the same year for the same house -Asxiots, [45954.1-Melting Zino.-I should be very glad galvanic-battery purposes. I have tried over d melt zine so as to be able to form it into solid I could through your columns obtain knowledge, again, but always get it in a kind of porous state, is of very little use for that purpose. If the flux used in melting it I should like to know what t AN AMATEUR MECHANIC. [45955.] magnet with commutator and mail pulley rece Magneto-Electric Machines -! have a permanent 6in. horseshoe magnet and nee revolving in front of the hosphoe mene il between two centres, the poles of the cleanes other, touching the commutator. From each reha most touching, and two brushes, insulated fre by connecting the te minals, or by connecting is wire led to two terminals. I can get sparks in slote some of our electrical friends, will assist me in the induction coil, but n t without. If Mr. Lancer I shall be greatly obliged.-J. E. W. able [45956.1-Magnetic Variation.-Can any of tell me what kind of oil is this from what er á á what substances or chemicals undergo a change in dat [45961)-House front.-My house is built dṣe if you would kindly describe the best methods fores 3 question, which has given rise to much s your readers kindly give their opinious on the flo [45963.1-Range of a Projectile.-Will somet engaged on both sides of the a gument -Two S amongst friends of mine, men of admitted ability be the same calibre, fired with similar charges of pos and projectiles of equal weight to give the same range of the two proj etiles! and if so, why, al high, and the other at the top. Both guns are fis velocity), are placed, one at the base of a dỡ m horizontal position. Will there be any difference d what extent? To take an extreme case, suppose 10,000ft. gun is tired under similar conditions from a b What will then be the horizontal range exhibition in Melbourne, some very beautiful theory, and (b) in practice ?-GRAVITY. 145964,]-Glass Transparencies -At the Many of them were copies of well-known pictures!! t sparencies on glass were shown n the Belaian or the Dresden gallery. Some appeared to have been b in; others partly etched and partly burnt; but of teel about them. I should be glad it some of our contits them photographs, but could give no further intorta am not sure. The persons in charge of the eart could tell me how they are den, or refer me to some mol reader of "E. M." kindly tell me what is the that gives details of the process.-AN OLD FELLOW [45965.]-Musical Wire Gong.-Will size musical wire gong that can whether it could be heard easily at 200 yards distal v be procured the open air -H. T. -- Is the ma [45966.]-Legal.-Will Mr. Wetherfield answer a following?-A bother died some time back, and die having di d since my brother); and now another 92 wife and five children unprovided for. My sister-in-a brothers has married my sister-in-law. west to live with ray father, he being a widower h legal ? and who is obliged to maintain the childr previous marriage my father S. F. F. H. or my brother centre of the arbor, from which a pivot has been br PRACTICAL WATCHMAKER."-Your mode of findi [45967.] Broken Pivots. - To seems complicated, and to require expensive tools, you not show a simpler way to find the replace the pivot?-NAGLECTED APPRENTICE. have broken a large marble mortar in three press heavy Pounding. Will anyone tell me the best waƑ * <P> 145968.-Repairing Large Marble Mortar-i pair it -GaoOCER. 45969.1-Boiler Power.-I have a 27 ft. by Galloway tubes in each. I hope some of our readers | 10in. boiler with two flues, 2ft. 3in. each, with th** oblige-O. C. show me a simple way to find the horse-peri, ** 145970.]-Drilling Hard Steel.-Would" Practical Watchmaker," or others, kindly let me know he best way to drill hard steel, such as a click spring of bar Geneva ? and also whether I can buy separately the rilling apparatus belonging to the turns for drilling the oles for pivots, &c. If so, what would be the probable pst 1-E. W. E. [45971-Metal Planing.-Will anyone suggest an rangement to alter my pla aing machine, which works ekwards and forwards on rack and pinion, so that the andle will turn one way only, to adjust length of cut. ust stand close to machine while working? Bed 24in. ylin.-LONG TOM. (45973.1-Flywheel.-Would a flywheel be of much e to drive bin. backgeared lathe instead of by foot! If best size for wheel?-LONG TOM. 45978.]-Parrot.-My green parrot's nose runs-what the canse what the cure? It lives in the country, d regularly goes upstairs to bed on account of cold J rats.-JOHN ALEX. OLLARD, 136, Fenchurch-street. [459741-Jute and Cotton.-I bave a sample of th, said to be a misture of the above. How am I to ove it! And I want to ascertain its value.-MICRO. [45075-Boiler for Model Engine -Could any ad reader give me the sizes for a boiler to work a horintal engine of 3in. bore and 5in. stroke, so as to drive amateur lathe, 4i. centres, to turn iron? would a Aller engine not do?-G. M. L. 43976.1 Hall Marks. In your No. 706 of tober 4, 1878, much information has been given as to marks of the Goldsmiths' Company, by which the te of the marking and presumably, therefore, the king of the article, can be ascertained. Can any der inform me what other companies have bad this cess of hall-merking, and in what places was it done? 1 what were the marks? I am from the North (Lanhire), and some of my ancestors came also from Yorkre. I have some old silver plate with marks which do appear to correspond with those of the Goldsmiths' apany. Hence my question above.-Z. Y. X. 13977.1-Artificial Cable. - Will "Sigma," or le other electrician, tell me how I can make an artifiI cable to represent one of the Atlantic lines, so far as rents and signals are concerned? Will the tappers of ingle-needle answer the same as mirror keys? mend any better oil, or can anything be added to it to lessen the unpleasant odour -OTTEE. [45984,]-Condensed Milk.-Two of my friends are feeding their babies on condensed milk-d luted, of course Would Dr. Edmunds recommend this in the absence of muk from one and the same cow?-Buzz BEF. [45985.1-Debtors in the Isle of Man.-Will Mr. F. Wetherfeld say how I can recover a small amount from debtor in the Isle of Man (under three pounds) most quickly and inexpensively? I believe the English county-courts have no jurisdiction in the Island.-KAPPA (England). frigerator in a st re-room, something after the following [45986-Refrigerator. -I want to build a small redescription, to be built into a recess in the wall, the lower part to contain a block of ice about 2 or 3ewt., and the upper part to be fitted with shelves and hooks to contain meat, soups, &c., when the weather gets warmer. Will any fellow-reader kindly tell me the best way to construct it, and what materials I must use in order to make it as successful as possible, and the ice not to melt too fast ?CONFECTIONER. [45987.]-Siemens Dynamo-Machine.-Is the core of the armature used in the 70lb. Siemens machine a solid block of iron, or an iron cylinder fitted on a wood block? Is the outer surface turnished with recesses for holding the wire coils, or is it equal all round? What is its length and diameter? Also, if recesses are used, what number, and what depth and width? Is the wire envelope which incloses the fiel magne's wound directly on the iron bars, or is it wound on wood bobbins? -LANCA SHIRE. if a fin. objective of 70 is capable of resolving Fleuro[45988]-Microscopical.-I shall be glad to know sigma fasciola.-CHARON. [45989.]-Lake Bottom.-I am anxious to form a small artifcial lake of rather less than an acre in extent in the middle of a wood where a space has been cleared. To a considerable depth below the surface it is entirely peat, and in wet weather is frequently covered with flow from a small drinking-fountain. Can any of your water. The only supply besides rain would be the overreaders suggest a really practical way of making the bottom in order that the water may keep clear? An answer would greatly oblige-J. [45990.]-Organ Pipes.-Having partly made a set of wood stopped diapason-pipes for a small chamberorgan of four stops, would "Uranium," or some other of our esteemed organ correspondents, kindly advise me in the following?-The height for eutt ng up mouth of 4ft. CC, tenor C, and mid C? Thicknes of lip for each of those named and should the lip be left squre on edge, or rounded inside and out? Also the depth to cut in cap for windway for each of above, size of hole in block for foot, size of hole through foot? Should the CC pipe be 4ft. long from block, or allow thickness of stopper longer? And what would be a suitable wind-pressure for voicing such pipes, and how is it measured-say, if water fall lin. in tube, and rise 1in. in the other? Is this called 1 or 2in. pressure Information on the above would be esteemed a great favour by-D. W. C. the WATCHMAKER," OR "A FELLOW-WORKMAN."- What is [45991.]-Watches. To "SECONDS' PRACTICAL tion a sharp cuting substance to be used after the graver proper use of the white powder "Diamantine"? Menin reducing watch and clock pivots, and arbors; also a finer "stuff" for giving a black gloss and finish. NEGLECTED APPRENTICE. 45979.)-Medical-To DR. EDMUNDS.-A little girl, [45992.] Compensating Expansion Balances.-Will auy watchmaking subscriber tell me how expansion balances are compeusated?-P.VOTE. like the opinion of your railway correspondents upon the [45993.-Railway Distant Signals. -I should question of distant signals. Should they be dises or arms! and in approaching a junction, should there be two "distants" or one The object of the question is to obtain the best opinions, and to ascertain the latest improvements ucoa the different lines, because I find the siguals in many districts very defective. Should green [45994.1-French Polishing Fretwork.-Can anyone inform me how to French polish small fr-twork articles, such as carte-de-visite frames, spill cases, &c.! I have tried the ordinary polish, but cannot use it to my sat sfaction, as its "clogs" all the fine parts up. Is there such a thing as brush polish, and if so, how is it made and used? I should like to know if anyone has tried ordinary varnish, very fine, and applied two or three times. Any information will oblige-R. T. T. [45995.]-Embossing and Gilding on Glass. -Would some correspondent give me a few hints on embossing and gilding on glass, and the materials used? 5980.]-Legal-Will Mr. F. N. Wetherfield kindly r the following-A man dies in Melbourne, Aus--G. W., Leamingtou. , intestate; amongst his papers is found a memo. of vishes, a copy of which is sent by his next of kin (nephews) to his next of kin in this country (nieces) their signature of acceptance (these nephews and es are cousins, not brothers and sisters). AccompanyThis memo. is a statement, to the effect that the heir w, eldest nephew, gets th- land, &c., as he would in country, &c., &c. Now, the legal advisers of some e nieces say that in Australia there is no her atand the advisers of the others say that Australia an English colony, is subject to English laws, ch is right? Also, can you say what is the probate on an intestate's estate, nephews and nieces inherit-PARTICIPATOK. 5081.]-Test for Oils-Will someone kindly give etical, but simple, test for relative values of olive, , and rape oil-not one as against another kind, but which is the best of two samples of each of above, [45996.]-Watches. -To "SECONDS' PRACTICAL WATCHMAKER,' AND "A FELLOW-WORKMAN."-You recently gave some excellent instructions for springing and timing Geneva and lever watches; you give five beats to the second in Geneva watches, and nine beats to the two seconds in lever watches. May I ask does this rule apply to watches of all sizes, say, for instance, may I spring an eighth or tenth size, or an eighteenth or twentieth size watch after the above rate? If the above counts only to apply to one size, how shall I determime all the other counts for the different sizes 1-NEGLECTED APPRENTICE. [45997.)-Paper-Making.-How can I make a paper that will not stretch when damped?-W. O. T. [45998.1-Slide-valve.-Can someone inform me if it is possible to apply a slide-valve to a cylinder 6in. bore, and 6in. stroke, so as to cut off steam at one-third of the stroke, and to retain it to nearly the end of the stroke? The dimensions of the portholes are:-Exhaust, lin. by 2in.; steam-holes, in. by zin.; in. space between exhaust and each steam-hole; length of steam-chest inside, 6in.-CRESCENT. 5982.]-Photo. Transparencies-Can a positive sparency be taken direct of any objec: on ordinary ine plates, so as to obviate taking a negative first, printing from that when one copy only is required. [45999.]-Jewellers' Solder.-Can any of your by what formula?-MEM. readers tell me if there is any particular solder for 983.]-Oil for Microscope Lamp.-I have used making p'atinum adhere to gold! I have tried both microscope the best paraffin and Belmontine that silver and gold solder, and find it breaks away with the procure, but find the smell it gives out very dis- least strain. Also, if there is any way to keep it from cable in a sitting-room? Can any of "ours" recom-warping when heated ?-JEWELLER. NOTICES TO CORRESPONDENTS. CORRECT SOLUTIONS to 718 by J. Schmucke, W. J. Jubb., H. Plan k, and S. L.; to 719 by W. J. Jubb, and S L.; to 720 by W. J. Jubb, H. Planck, J. Schmucke, S. L., and Q. P. Q" (two solutions); to 721 by W. J. Jubb, H. Planck, and S. L.; to 722 by W. J. Jubb, H. Planck. J. P. (neat, and not so easy as it looks at first sight), S. L. and J. Schmucke; to 723 by W. J. Jubb, H. Planck, J. P. (very pretty), S. L., and J Schmucke. C. P. (Dalston).-Many thanks for further contributions. A. WYLDE.-Not up to the mark. Have written. Shall be glad to have further attempts. THE THREE BROTHERS (Yokohama).-You will have seen ere this that you were anticipated. Thanks for coinmunication. C. H. C.-Thanks. Always welcome. F. M-You are quite right-the king should be moved first. ANSWERS TO CORRESPONDENTS. All communications should be addressed to the EDITOR of the ENGLISH MECHANIC, 31, Tavistock-street, Covent Garden, W.C. HINTS TO CORRESPONDENTS. 1. Write on one side of the paper only, and put drawings for illustrations on separate pieces of paper. 2. Put titles to queries, and when answering queries put the numbers 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 addresses of manufacturers or correspondents, or where tools or other articles can be purchased, or replies giving such information, cannot be inserted except as advertisements. 5. No question asking for educational or scientific information is answered through the post. 6. Letters sent to correspondents, under cover to the Editor, are not forwarded; and the names of correspondents are not 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 questions such as are indicated above, which are only of individual interest, and which, if not advertisements in themselves, lead to replies which are. The "Sixpenny Sale Column" offers a cheap means of obtaining such information, and we trust our readers will avail themselves of it. The following are the initials, &c., of letters to hand up to Wednesday evening, Feb. 1, and unacknowledged elsewhere: G B. STRIDE.-E. P. Alexander.-Lucien Powlett.-F. H. Bolton.-H. Scholefield.-Moore and Brown.-Sir F. Macnaghten.-Birch and Co.-J. K. P.-Waes Hael. J. Main.-8.-A. L.-Engineer.-J. W.-R. E. V.-F. A. Brooks.-W. H. H., Brixton.-Mancastrian Ted.F. W. Mackenzie.-L. W.-W. J. R., Chelsea.-R. T. B. -J. Kendall.-Xanthidia.-Woodleigh.-A Driver.F. Jones.-Alb.-A. Manock.-Sunlight.-A Fellow of the Royal Astronomical Society. PI. (Thanks; you will find the process for making artificial indigo on p. 537, Vol. XXXII., the number for Feb. 11, 1881, and Prof. Roscoe's lecture on the subject in Vol. XXXIII., p. 324. The last two questions in the query await an answer, as the manufacture has no doubt been improved, and the cost probably reduced, since Prof. Roscoe delivered his lecture.)-G, HUDSON. (We cannot help you to form mental conceptions. If you can count 100 in a minute, then it will take 10,000 minutes to count a million. You can easily reckon how many weeks. 2. Siemens' method of melting, steel by means of electricity was described on p. 555, Vol. XXXII., nearly a year ago.)-INOLE. (What is it you wish to point out? The boiler will not burst unless it is strained nearly to its bursting point; and the same remark is true of the membrane.)-VALETUDINARIAN. (Try whole-meal bread, wheaten groats, or a glass of cold water first thing in the morning. You will find a discussion of the subject in Vol. XV., pp. 365, 390, 441, 467, 491, 517, 544.)-AMATEUR. (Mere examination questions, answer d in any textbook. To the first, however: Richard shortened the length of pistonstroke and multiplied the travel of the pencil; but no one thinks of comparing them nowadays.)-A SUBSCRIBER, Stalybridge. (Dissolve pure asphaltum in oil of lavender, or, it common work, grind a little ivory black in some copal varnish. 2. For japanning, see pp. 36 and 236, present volume.)-E. MELDRUM. A good deal would depend on the "lamp"; but 30 possibly would do. See recent numbers.)-XERXES. (We cannot, because no such book is in existence. See p. 474.)ALPHA. (Edison's was described on p. 510, Vol. XXIX.; the new Gower on p. 510, Vol. XXXII. See also the indices of recent volumes.)-ANXIOUS. (Do you mean froth?)-A. B. R. (Make one of the machines described on p. 179, Vol. XXXIII., No. 840, or consult the indices, especially that to Vol. XXXII.)-HERCULES. (Keep) your diet as much as possible to meat and vegetables, avoiding starchy matters and sugar. To be stout at your age must be constitutional, and it would be advisable to consult a medical man before adopting any of the methods of reducing corpulence. You can do no harm by exercise, in moderation.)-A. J. F. (You will find a full explanation in Nos. 773, 774, It is simply a little apparatus with three punchers or pistons.) BOIL R. (For model boiler, you must refer to the last two volumes. Perhaps that on p. 286, Vol. XXXII., will suit you.)-Cosmos. (Do you want both, or what? Full directions have been given in back volumes.) TREADLE, Boston. (Do you mean bronzing (a sort of varnishing) or browning, done with acids.)-IMMOVABLE. (The conditions are too much-lasting, pliable, proof against moisture and heat. See p. 10, Vol. XXIX., or try dermatine.)-HARRIET LONG. (We gave an illustration of the audiphone on p. 42, Vol. XXXI. We do not know the address of the agents. A query on the subject is inserted this week. Watch the replies it may bring forth.)-DUPLEX. (See the index to the last volume. You will find your queries answered in recent numbers.)-F. G. SPENCER. (See answer to "Inquirer" on p. 460, or search the indices.)-INQUIRER. (Boil the tar, stirring occasionally until all water has evaporated. Have a heap of clean washed but dry pebbles, and mix the tar with them. When coated, lay them where wanted, level, and pour over a layer of hot tar, covering with dry sand or crushed fluorspar or limestone. 2. For much valuable inf rmation on working in concrete, see pp. 23, 47, 92, 155, 477, 617, 666, Vol. XV.)-F. S. C. (If you can get the glass where bare perfectly clean, you may be able to manage it. On a perfectly flat suriace place a piece of tinfoil, and spread a globule or two of mercury over it. Press the glass firmly down on that, and leave it for several hours with a weight on it.) -EDWARD JACKSON. (You will find a rule in most books on mensuration; but see a discussion of the subject in Vol. XII., pp. 131, 203, 227, 257, 282.)-A FELLOW OF THE GEOLOGICAL SOCIETY. (We have no space for the discussion of " Thought Reading," or whatever you like to call the phenomera just now. We had a fairly lengthy discussion on the subject not long since, which we suppose you read. If not, you had better do so, more especially "Sigma's " letters. There is not much more to be said on the matter than he said then.) -SCOVANDYKE. (We cannot ask Mr. Wetherfield, or any one else, to inquire into or give opinions as to the respectability of public companies or private trading firms. There are inquiry offices-Stubbs', for instance -which furnish such information, but only to subscribers, we believe.)-MANCHESTER. (The best thing is to give the ground a thorough good dressing of hot lime when turning it over, working it well in, and subsequently, as the crops appear, to sprinkle a little lime on the leaves when the slugs are numerous. 2. It depends on the crops, but it should, as a rule, be used sparingly.) -A. M. B. (Use ordinary rubber solution. You will not succeed in re-colouring it. "Sunlight" gave some good instructions on making cheap and handy lantern gas holders on p. 45, No. 834.)-ANNA. (The trustees under the will can surely employ a solicitor. We can hardly spare space to ventilate the grievances of a young lady who, after all, may patiently wait till she is fiveand twenty for the exclusive use of her maid, horse, and groom.)-REV. S. R. CRAIG. (We know nothing at all about the advertiser you inquire about, and cannot answer such questions privately. The first and last of your queries are inserted; we cannot spare space for the others.)-C. J. H. (Possible enough, certainly; but your arguments are of a negative and very nebulous character. It is easy enough to hint that rules of health and the like may be wrong; but have you anything better to offer in their place?)-A. S. R. (There is no "Science of the Weather" yet, and we regret we cannot meet your wishes by opening a corner of the kind you mention. You will find some statistics of the nature asked for in " Whitaker's Almanack.'')-M. I. D. (Probably a cold, or caused by an abscess at the root of a decayed tooth. If the latter, have the tooth extracted at once.)-H. HABMAN. (Nothing that we know of will enable you to utilise ordinary water-colours for dyeing kid gloves.)-CYMRO. (Vellum is of the same colour as parchment, or a shade deeper.)-DYER. (There is no book of the kind, and we do not see how such knowledge is to be obtained except by long experience in the trade. Even experienced buyers in large City houses are at fault sometimes with unfamiliar materials.)-ONE IN TROUBLE. (Try Rendle's " Electric Paint Remover," advertised in these pages.)-H. CRIPPS. (Try benzoline.)-THOMAS. The theories" are rubbish, and the practice a delusion. There is no beneficial action at all, except that which is caused by the effect produced on the imagination of the patient. Do not waste your money on any such appliances.)-JOHN THOMAS. ("A." is certainly liable morally, and legally, too, if the agreement was stamped afterwards. How does he know it has not been?)-A. N. J. (Tea is not a good thing to take with meat. It hinders digestion. Plain water is best; but beer in moderation will not interfere with your riding. No special diet is necessary beyond a general adherence to the principles enunciated in the letter you refer to.)-H. T. (We never saw the prize puzzle referred to, and should say it was a hoax.) CARINO. (We believe we shall describe and illustrate the engine referred to shortly. There are several peculiarities about Scotch law that render it advisable that you should take local legal advice on the subject. A Scottish landlord has, we believe, powers that he would not be allowed to exercise our side of the Tweed.). LIBER. (Try a liberal application of paraffin.)P. W. R. (Your own medical man will pre-cribe a tonic equal in every way to the high-priced advertised preparation at a fourth of its cost, or get 30 grains of citrate of iron and quinine at any good chemist's; dissolve in a six-ounce bottle of water, and take one tab'espoonful three times a day.)-B. E. A. (The damp, in all probability, rises from the foundations, and nothing but the insertion of a damp-proof course will have any permanent good effect.)-A. W. CARLEY. (Fourpence, through any newsagent.)-COUNTRYMAN. (The best medium for advertisements for situations of all kinds in connection with the building trades is the Building News, published at this office. The charge is twenty words for one shilling.)-GAS ENGINE. (Yes; because the power is applied steadily, and the explosion is not so violent. With plain gas and air, a great deal of heat is imparted to the cylinder, which has to be extracted by means of water.)-DABBLER. (Put cuttings of zinc in hydrochloric acid until it will dissolve no more. Some add a little sal-ammoniac.)-G. GROVE. (Merely a theoretical term. You will find diagrams in Molesworth's Pocket-book.)-AMATEUB. (We are not aware that such a book is published; but you will find ample directions in back volumes.)-A CONSTANT SUBSCRIBEB. (Varies with the speed and weight of train. See p. 136, present vol. for a diagram. 2. You can use rubber solution by roughening the glass, or dissolve powdered shellac in strong ammonia solution. The latter must be kept some time before it is ready for use.)-IX YEARS' READER. (See a similar query, and watch for the replies.)-S. HUNT. (A "Gem" is not suited for such work. You could, however, cover the parts you do not want, and take the rest in the ordinary way.)-Ax AMATEUR PHOTOGRAPHER. (Must consult back volumes, or procure one of the many manuals of the subject. The question is too indefinite.)-W. P. H. (See p. 384, No. 692. Plenty of power with such a pressure. 2. He used what is known as the injector. Ten feet or more, but not with advantage- that is, vertical distance. The horizontal is limited only by the friction of the water in the pipe, which might be very long.)-DAUBER. (Dissolve 25lb. of soda in a gallon and a half of water. Melt 80lb. of tallow, and as it cools gradually pour in the soda solution, stirring all the time until it becomes "grease.")-C. TAPROBANE. (The subject dropped at the time owing to the decision of the Courts; but when space avails we may take it up again.)-R. P. (See pp. 36 and 236, present volume, for hints n japanning.-A RECENT SUBSCRIBER. (For hard soldering, see pp. 170, 264, 334, 455, last volume. Look through the ita. too.)-G. FRYER. (Fetter wait for Mr. D.'s reply. T other matter is really nothing more than such a d scription as can be found in the prospectus, asie rather too much of an advertisement )-S. W (Sprague's "Electricity," published by E. and Fy pon. Plenty of classes in London. Inquire at one a the Board Schools, where they are often held.)-A. La. GARD. (We do not know the cell named.)—Maraz (Yes, to most of your questions; but see the artic p. 413. By using glass cells it can be seen when th hydrogen is given off, and you cannot charge too ma though you may waste current. It is a question ti experience with the individual battery.)-R. A. G. T old form of Leclanché; saturated solution of sain moniac and water. You must melt the pitch out 1 "Weak eyes" are not necessarily synonymous wit short sight. If the latter, spectacles are cartuch needed, and they should be adapted to the sight. I child can read this at a distance of 10in., she is scary short-sighted.)-A NEW READER. (We do not see wh you can have. It must be piano or harmöntuma - the other. Ample information for the construmi 1 .. either will be found in our back volumes; but we late yet to hear of any instrument between the two su you ask for.)-Ć. G. (You will certainly not st. cheaper instrument if you want a reliable repla temperature.)-T. M. (Possibly a polypus; you had better see a surgeon) J. S. G. (They are drawn, b the process could not be worked economically small scale, and a description would occupy pages with illustrations fof plant, &c.)-TrsaDEL (Instructions for galvanising iron will be found cap 273, No. 739, and in many other back numbers, and japanning iron on p. 593, No. 726, and p. 611, No. 12 J. GREEN. (See Newton's Principia III. 10. He judged the earth to be between five and six times as mast the same bulk of water, which is the truth. We do za know to what ancient "geographer" you can be referrin AN OLD READER. (That you cannot be, or you would how many times your query has been answered. H ever, here you are again, though the "storm-glass" really of little use when made. Take a glass tube le long and lin. in diameter, closed at the bottom, nearly fill it with the following: - Camphor, tr sal-ammoniac, 1dr. Dissolve the above in 40% pure spirits of wine, then add distilled water, dropi; drop, until enough of a white precipitate is thr down. The top of the tube may be corked or coverd with a bit of wet bladder. In fine weather the fa clear, and the precipitate lies at the bottom of the tale but rises gradually on the approach of stormy weather J. HOGBEN. (Rub down a new surface to it, or bag another-cheaper, perhaps, than wasting your time ALPHA. (Dissolve solid paraffin in benzoline will take up no more, aud give the cardboard a casti each side. The benzoline must be placed in a small g or gallipot, and the cup placed in a larger vessel of Lat water.)-W. H. B. (No, you must have special appea ratus.)-YourG HAND. (Of course you will have ton the consent of owners of property, and of the hal authorities as well. If resident in a large town, ya had better employ the company.)-A. H. Goodw ("Sigma's" book is published by E. and F. N. Sp Charing-cross.)-J. C. A. (You mean provisional pro tion. Cost about £S to £10 108., including agent's fe and giving protection for six months.)-B. H. The is no book of the kind. The one mentioned give the principles, but not practical details, except as examp You will not be able to get anything better than is to f und in back volumes.) Every Workman connected with the Building Trad es requiring a situation should advertise in "THE BULL ING NEWS," published every FRIDAY, price Fourpesce at 31, Tavistock-street, Covent-garden London, W.C. "THE BUILDING NEWS" is the Principal Journal, regis senting Architects and Builders, and has the largest circu of any Professional Journal in the kingdom. " Every Workman should insist on seeing "THE BUILDING NEWS every week at his Club or Coffee House. He wil tr more" Lists of Tenders" for new work in it every week than any similar paper, and can thus judge where work is likely had. He is also specially invited to make use of "Inter munication" if he wants to know anything about his tra write to the Editor if he has any suggestions to make 4243 ad vertise in the paper when he wants work. The charge for Advertisements for Situations is One Skill for Twenty Words, and Sixpence for every Eight Words after The remittance should be made by Post-office order. B numbers cannot be sent cut of the United Kingdom by ordinary newspaper post, but must be remitted for at the rate 3d. each to cover extra postage. Messrs. JAMES W. QUEEN and Co., of 924, Chestnut-street, Ph delphia, are authorised to receive subscriptions for the States for the ENGLISH MECHANIC, at the rate of 16 25c. gold, or Thirteen Shillings per annum, post-free. The will be forwarded direct by mail from the publishing of London. All subscriptions will commence with the pum issued after the receipt of the subscription. If back na required to complete volumes they must be paid for at the r 4d. each copy, to cover extra postage. Vole XXIV., XXVI., XXVII., XXVIII., XXIX., XXX., XIII XXXII., and XXXIII., bound in cloth, 76. each. All the other bound volumes are out of print Scher would do well to order volumes as soon as possible after th clusion of each half-yearly volume in March and Septembe only a limited number are bound up, and these soon ri print. Most of our back numbers can be had singi. each, through any bookseller or newsagent, or 2id. each, from the office (except index numbers, which are 3d. cach, post-free, 3 d.) Indexes for each hair-yearly volume up to Vol. X. (except Tie II., III, IV., V., and X. inclusive. d. each. Post free d Indexes to subsequent vols., 3d. each or post-free, d. Cas binding, ls. 6d. each. Subscribers are requested to order Cases and Vols t their booksellers, and not to send direct. The regulations post-office prevent their transmission through the Post. slide, which forms the eccentric cutter, is And now a few words on what I claim as The English Mechanic worked by a strong spring, which keeps the a great improvement in this particular in AND WORLD OF SCIENCE AND ART. FRIDAY, FEBRUARY 10, 1882. THE ROSE-CUTTING FRAME. small steel roller always on the rosette, and strument. Fig. 3, it will be seen, is a small as the spindle upon which it is all fixed is drilling instrument, into which drills of any moved round by aid of the tangent-wheel shape may be fitted, on precisely the same and screw at the back, the front slide oscil-principle as any other ornamental drill; and lates, and the roller or rubber, as it follows the great advantage derived from it is that the figure, whichever it is that is on the in- the drill, which becomes the cutter, can be strument, will cause the cutter to follow out driven at a high speed, and by means of the the same kind of pattern on the face of the winch-handle, seen in Fig. 1, the whole wood, or whatever may be the material to apparatus is moved over the same ground, be worked. The production on the wood as it were, only at a very reduced speed, will not be a facsimile of the rosette, be- which gives the drill time to make a clean cause the diameter of the steel roller will cut; the depth of the pattern is, of course, not allow it to go to the bottom of sharp governed by the stop-screws in the tool-box of the slide-rest in the same way as for ordinary eccentric pattern. WE now arrive at a more extensive and, corners. The tension on the spring is consequently, more expensive, branch strengthened by adjusting the small milled of ornamental turning, and one requiring a head upon the end of it; and, if the spring further complicated assortment of tools. be made stronger, it will naturally admit of The present illustration is of an instrument its cutting a deeper pattern with the fixed which, for the production of patterns on tool. When this instrument was first introsurfaces, is a very interesting tool to work duced, the eccentric cutter in the front only As there are overhead motions of different kinds, it will not be out of place to refer to this particular adjunct to the lathe. Provided the band has to lead from the bar on which the driving-pulley runs, a difficulty vith, and the number of different patterns | extended on one side of the centre; but it opposite direction. There are, of course, a First, then, it will be seen that the front (namental turner. will present itself on account of the different and unequal positions the instrument must take in its course round the rosette. With the improved overhead motion I now make, this is overcome by the counterbalance weight, which will allow the band to give and take almost any amount; but in the other case it is different, the band is to a certain extent rigid. This I found a considerable drawback to my improvement, because scarcely anyone would be disposed to have a new overhead motion for the sake of one instrument only, and to overcome this obstacle I had some strong bands of small diameter made in vulcanite indiarubber, and they answered so well that I found them very useful. I have now stated briefly the object of this instrument, and how it works, and for the benefit of our readers I will endeavour to tell anyone caring to do so, how to make one for himself, as it is a very intricate thing to do, and requires a deal of explanation. I hope I shall not be blamed if I occupy a somewhat lengthened space in giving the various |