but guessing at the meaning, I should say, yes. There are no "pint" cells of the improved battery; the principle involves large cells; and my remark as to the current yielded applies to the regular size in half-gallon jars. Made on a small scale, there would be too little surface to the negative element, and both power and constancy would be sacrificed. As to the coupling, a simple trial will tell best, as in my ignorance of the length of wire I cannot be sure. Probably two cells in series would be quite sufficient, and very likely one; and, therefore, the "quantity" coupling would be preferable.-SIGMA. P. S. Since writing the above I learn that a misprint is the cause of my remark as to capacity of the cells, which should have been "3 three pint cells." These would suffice, but if by 6 convolutions is meant simply 6 single turns of wire, that would not be enough, and would be very bad economy. A length of wire should be used, giving resistance equal to that of the battery, an explanation, which many will not perhaps understand, but which will be made perfectly clear at an early date. you have a leading screw to the lathe-bed then [4818.]-PLANING MACHINE.-"Tometer's" query on this subject seems to be its own answer-How can he fit up a planing machine when he does not know how patterns are made? Answer-how can he ?-J. K. P. [4816.]-CLEANING FURS-SABLE AND OTHERS.Thoroughly sprinkle every part with hot flour and sand and well brush with a hard brush. Then heat with a cane, comb it smooth with a wet comb and press carefully with a warm iron. For ermine use plaster of Paris instead of flour and sand, and treat in the same way.-J. [4795.]-ENAMELLING SLATES.-The slate having NASH. been reduced to a perfectly level surface, a coating of [4844.]-NUMISMATIC.-In answer to Mr. Samuel colour, either red, green, or black, is applied according to the stone, it is intended to imitate. For black, Man-Smith, I beg to give the following suggestions:-Procure a piece of mahogany, size about 18in. by 12in., and oneder's tar varnish is sometimes used with good effect. The slab is then thoroughly baked in an oven heated eighth or three-sixteenths of an inch thick, according to the thickness of the coins required to be exhibited. from 180 to 250deg., from twelve to forty-eight hours Then with a carpenter's centre-bit drill holes of the reaccording to size. The next operation is dipping. The colours, say grey and white, are then floated on to the quired size entirely through this board. These will form the cells. For the bottom, screw on to the pierced board surface of a cistern of water over which they float another piece of mahogany of the same size, but only naturally into the shapes of the streaks of colour seen one-eighth of an inch thick. If the coins are fine and in marble. The slate, with its black ground, now burnt valuable, a piece of silk velvet may be glued upon the in, is "dipped" into the surface of the water receives from it the thin coat of colour. The slate again has to bottom board before screwing it to the other. This will appear through the drilled cells, and will form a smooth go into the oven, and when sufficiently hardened, a coating of enamel is applied. Another baking to harden surface for the coins to rest upon. When the coins are the enamel and the slab is then vigorously pumiced to arranged in their respective places, a small oblong label reduce it to a level surface. Baked again it is once more below the cell for each coin. I do not mean the names should be pasted on the upper mahogany board, just pumiced, and this time goes into the oven with the to be placed under the coins, so that they have to be pumice wet on its surface. If necessary this last lifted up to show the labels; but on the upper board operation is repeated. The slab is then ready for polishing below the cells themselves. When all the foregoing is which is effected firstly by woollen cloths and fine sand, completed, a sheet of glass, of the exact size of the board, next by the finest and softest French merino, and lastly should be placed over all. It may be slid into grooves by the hand and powdered rotten-stone. The" dipping" in a neat edge fixed round the whole tray. This, I think, process is not applicable to imitations of all stones. Some granites for instance are best imitated by and would be very safe if the glass was strongly fixed would be a very serviceable manner of exhibiting coins, splashing; others by splashing and sponging combined, into the edge. The only drawback is not being able to while some have to be hand grained.-KAPPA. see both sides of the coins. This may be remedied as follows:-Let the cells be pierced entirely through a piece of mahogany board, which is of the exact thickness of the coins. Then fix a sheet of glass on each side, dispensing with the second mahogany board. Thus by turning the tray over, both sides of the coins may be seen. This latter mode, having much the appearance of picture frames with glass back and front, is used for the medals in the Sonth Kensington Museum. A number of these frames are hinged vertically to a circular pillar, and may be looked at and turned in the same manner as the leaves of a book stood up on one end. I hope that the above notes may be of some use to Mr. Smith.HFNRY W. HENFREY, M.N.S., &c., &c. [4799.]-SCIENCE AND ART DEPARTMENT.-To obtain a medal it is necessary first to pass the elementary grade examination, and then the next or any subsequent year, to be one of the best half dozen or so who have passed first-class in the advanced stage. A selection of five or six of these is made by the examiner, and they have to undergo a further examination the same year. The best of these then gets the gold medal; the second best, a silver; and the two next a bronze each. Medals are not given for the honours (examination. I am not aware if any rule has been laid down as to whether one who has passed in honours can subsequently be examined in the advanced grade class examination of the same subject, and so obtain a medal. The only way of ascertaining is by letter to the Secretary.-IGNORANT IRISHMAN (A Gold Medallist). [4812.]-VERTICAL SLIDE REST.-In answer to "Tometer " I send drawings of a vertical slide to bolt on to the top of an ordinary right-angle slide rest, only for that purpose the bracket should be stuck on higher up the back of the slide than shown in the drawing. If [4845.]-ELECTROLYSIS.-If "Work" means what he says-viz., that he has tried to decompose water, neither six nor 60 cells will do it; in fact, water is not an electrolyte at all, and if pure is not capable of electric decomposition. If he means what is commonly called decomposition of water, that is to say, sulphuric acid dissolved in water, three Bunsen's cells willdo it freely without the coil; but if he is using the secondary or shocking current the "quantity" is so slight in this that he would only produce a few microscopic bubbles of gas.-SIGMA. [4846.]-LOGARITHMS.-" Work" states the question wrongly; or rather, the number given as answer must be wrong. The decimal point ought to be six places more to the right. As to working the example, Work" should read the introduction which always accompanies every table of logs., and which instructs how to use the column of differences.-J. K. P. [4847.]-NATURAL FORCES.-The best writings on these subjects are scattered through many papers in the scientific periodicals and transactions; few of the text books go fairly into the principles. Grove's "Correlation of the Physical Forces" was the first work on the subject. Tyndall's "Heat as a Mode of Motion," worked out the idea for that force, and Balfour Stewart's "Elementary Treatise on Heat," and Cazin's excellent little work," Phenomena of the Laws of Heat," are valuable contributions. Electricity remains yet in some confusion; even such a man as Tyndall feebly talks about the advantages of, for the present, working from the supposed two electricities, though admitting that there is probably no such a thing at all as electricity. One of my main objects in my papers is to clear this point up and give coherence to the vague views at present straggling about the scientific world. If "Thinker " has not read the earlier part of that series, commencing No. 242, I think the perusal might aid him; and, further, I wrote several papers expressly to make the correlation of the forces, and the most modern views of the subject comprehensible, and these papers might probably form a useful preparation for wider study. They are contained in Vol. X., pp. 58, 204, 288, 399, and 461; or in numbers 211, 217, 221, 226, and 229; but were not fully completed as they emerged into my present work, which engaged all my spare time.-SIGMA. [4855.]-BATTERY CONNECTIONS.-The best way is to solder the upper edge of the platinum to a strip of copper, coating the solder and copper with paraffine to protect them from the acid.-SIGMA. scopist would show "A. L. B." "how to do it" in five a jockey on the other (taking care to reverse the figures, [4866.]-WATERPROOFING TIMBER ROOFS.-The Mammoth Theatre, Berwick-on-Tweed, is roofed with thin boards, covered with composite millboards nailed down to the wood, and well tarred over; this is perfectly boards were procured from a neighbouring mill, and waterproof, and very durable. I understand the milldid not come to more than 2d. per square yard-J. LAMB. beating seconds is 89-13929in. in length. To ascertain [4869.]-LENGTH OF PENDULUM.-A pendulum the length of any pendulum giving a required number of beats per minute use this formula 39-13929 x 602 r being the number of beats required. So in the query of "Electro-Magnet, No. 1," 36-13922 x 602 17-39524 in. which is the length of 902 a pendulum beating ninety times per minute, or one beat = two-thirds of a second.-J. NASH. QUERIES. [4870.]-HARMONIUM CASE.-I have a large harmonium in walnut case, the polish of which is" rusting" so to speak, that is, a number of rough patches and streaks have appeared nearly all over the surface. Can any friend tell me what I can apply to restore the polish again, short of French polishing, as I am no hand at that? The draw stops in the above instrument are mahogany, covered with a coating of black varnish of some sort, very hard, giving the appearance of the "stop" being made of solid black wood. Can any reader tell me what this composition is, as I wish to coat two extra mahogany stops in a similar manner to correspond with those already in the instrument?-IVORY. [4871.]-TRANSPARENT SIZE.-I will thank any of my fellow subscribers to inform me of the best sort of size to fasten gilt paper or tin-foil on glass; and as the gilt side of the paper is to be next the glass, the size must be clear and transparent, and such as not to tarnish the lustre of the paper or the foil, and at the same time cause either of them firmly to adhere.ELECTRO MAGNET, No. 1. [4872.]-PRESERVING MUSHROOMS.-Will any reader tell me the best way to preserve button mushrooms so as to ensure their keeping during the winter and retaining their white colour?-A MAN COOK. [4878.]-BRONZING GUN BARRELS.-I want the exact mode of the black and white bronze given to gun barrels at the present time, to wit, the burning recipe: how long in, how often scratched per day if boiled till black, if so, how the figure is brought out. I have the copper trough for boiling, and the lead tank for taking out; do pretty fair but not the exact thing; will seme bright man give the particulars, and oblige ?-THE AMATEUR. inform me the qualifications for the above situation? I BER. [4877.]-PORTABLE WINDMILL.-Will John James [4876.]-COD-LIVER OIL.-Would some medical reader of the MECHANIC kindly answer the following [4856].-WENHAM'S PARABOLOID.-If this be fitted with an adjustable stop by which the light may be re- questions? Whether cod-liver oil, which has been kept gulated, and be also capable of very varied focal adjust-place, is still a good remedy for weakness and loss of for 7 or 8 years in pint bottles closely corked in a cool ments, there is no reason why it should not be used with flesh, or whether its good qualities have become imthe whole series of powers. But my querist can obtain pared by so long keeping.-THE WIFE OF A SUBSCRIa very good dark ground illumination by the aid of his mirror alone, if that be fitted so as to be capable of being thrown out of the axis of the instrument, the stage be there and the apperture thereof sufficiently large. I do not know that it is possible to tell" A. L. B. how to do this. A few trials will enable him to hit upon the right position of the mirror. He must bear in mind that no light must be thrown upon the lens, but just by one side of it. The object on the slide will refract a portion of the pencil and cause it to pass into the objective, carrying with it its message. Any micro (reply 4612) kindly favour me with information as to windmill for pumping? I want a means of keeping a cistern supplied at a convenient height, for domestic purposes, bath, watering garden, &c.-FRED. Row, M.D. [4878.)-STIFFNESS OF FINGER-I am a violinist, and for the last two or three months have experienced s painful and increasing stiffness of the first finger of left hand, especially about the knuckle joint, which has SEPT. 23, 1870.1 ENGLISH MECHANIC AND WORLD OF SCIENCE. 23 [4910.]-POROUS CELLS.-Which are the best to use naturally almost entirely prevented my playing on the relief, they being more durable than the limestone. You will see at once that it is a dangerous undertaking to instrument. If any of your numerous readers can suggest a remedy he will render me, and perhaps others attempt to get good specimens, as we should have to climb high, which would endanger one's life. Now as I similarly situated, a great service.-ROBERT HALL. [4879]-SECRET CODES.-I, in company with other know some little about chemistry I thought it was posof your readers, will be pleased to see a description of sible to act on the limestone with some acid, and therethe instrument of" cryptographer," (page 595). Also any by produce the same effect chemically in a short space further information of his plan that he may be willing of time that it would take ages to accomplish by the action of the atmosphere. Consequently I made a soluto disclose, as I have failed to discover it.-ARGUS. to four of water, but it acted on the fossils as well as the [4880.]-TO MILLERS-I have a pair of Derbyshiretion of sulphuric acid and water, sulphuric acid one part a brass in the bottom stone. It is 4ft. or 5ft. long, and has stones, 2ft. in diameter, also the spindle, which works in been driven from above. I have thought of fixing them to grind or kibble Indian corn, barley, or oats for cattle and pigs. I wish to ascertain how much work they will do? will it be worth the expense of fixing ? and also, the seemed to form a coating on the limestone that was in box in contiguity to the reed pan. Has any reader tried cannot see how the foot of the spindle can be lubricated. I think they have been originally fixed to grind paint. Informating relative to the above will much oblige. FARMER. [4881.j-CEMENT FOR SETTING STONES.-Can any of your numerous readers inform me how to make a cement for setting stones? I have tried mastic and isinglass, and most of the cements sold to jewellers for the above purpose, but they will not stand hot water. any one can give me a good practical recipe I shall feel much obliged.-RUBY. If [4882.]-VIBRATING CONTACT BREAKER.-Will any of your readers inform me how many times in a second a nicely adjusted vibrating contact breaker can be made to vibrate and what determines the velocity ? ARGUS. [4883.]-MAGNETO-ELECTRIC MACHINE.-I have made a magneto-electric machine which I wish to attach to an electro-magnet, so that when the machine is in operation the electro-magnet will support about two ounces. I cannot get the machine to work, and I appeal to you for help. The electro-magnet is perfect; with a few galvanic cells it will support an armature of 5 or 6 ounces weight. The coils of the magneto-electric machine are also perfect, when I send a current through them the cores become magnetized. The insulation of the contact breakers is also perfect as I can send a galvanic current through them to the magneto-electric coils. I should state that my magnet is 10in. long, each pole 1fin. x fin. full, and is placed as close as possible to the cores, so as not to touch.-A. SUTHERLAND. [4884]-GRIFFIN'S GAS FURNACE.-I should be obliged if any one could give me any description of Mr. C. Griffin's gas furnace.-LEVER. screw. [4885.]-DISCOLORATION OF LEATHER.-I am obliged to Mr. Scholefield for his sketch of press. Mine are round, the largest being 4in. in diameter and 24in. deep, upon which is placed the leather; the ram, which is about gths of an inch smaller in diameter than press, is then put upon the leather and pressed down with 14in. It will be seen that the pressure is very considerable, which I don't think any kind of wood (box included) would stand for any length of time. I have painted If it does not imthe presses, and intend trying that. prove the colour, I must re-bore the presses and case them with brass, and perhaps a zinc ram would then remedy the difficulty. I should like very much to get some information on hardening, if any brother reader could oblige. Could I soak them in any chemical which would hasten the drying? The time of pressing occupies about a minute, and that they may get thoroughly hard I have to let them remain in the presses all night. -G. A. G. [4886.]-DYEING.-Can Mr. Young or any other reader inform me of the best way of dyeing woollen black when it has been bleached with sulphur ?-F. W. HUDDERS FIELD. [4887.]-DIATOMACEOUS EARTHS.-Can any of your numerous microscopic readers give me any information respecting the cleaning and preparing diatomaceous earths? I have been trying for a long time, and with very ill-success. I have this week been examining some of Topping and Barnett's preparations, and I am disgusted with my own efforts, the last-named gentleIf any of man's slides being astonishingly beautiful. your scientific readers can give me a hint as to the manipulation, I should be glad.-F. G. [4888.]-STEREOTYPING.-I should be much obliged to "Amateur Stereotyper," who writes query No. 4784, if he would kindly say how he prepares his moulds of starch and whiting, and what success he has had with them. I should also be thankful to "George" (query No. 4742) if he will tell me how he obtains his music stereo, particularly if (as his query leads me to infer) the new process he speaks of is one which does away with the necessity of setting-up type. I am very much interested, as an amateur, in stereotyping, though hitherto I have met with indifferent success.-A CAMBRIDGE GRADUATE. [4889.]-HORIZONTAL WINDMILL. A question was asked some time back in your columns as to how Mr. Vallance proposed to stop or regulate his "horizontal windmill," described in No. 259, page 631, Vol. X., but I have not seen any satisfactory reply, which is much to be regretted, as the plan appears admirable; but as a fixture it requires a method of stopping which will ensure its safety in a gale. Mr. Vallance was not very clear on this point, and I am sure your readers would be much obliged if he would help us a little more.-C. D. C. [4890.]-THE PAINTER OF SEVILLE.-Could any of your poetical and dramatic readers inform me where I can find the above poem in print? I have heard it given as a recitation, but have been unable to find the piece in any book as yet.-ELOCUTIONIST. [4891.]-LONDON MATRICULATION EXAMINATION.--I shall be glad if any of my fellow readers of the MECHANIC will tell me whether they consider Todhunter's Mechanics for Beginners" sufficient for the natural philosophy paper at the London Matriculation Examination; also what book or books they would recommend for the thorough getting up of the chemistry, English literature and French for the above examination. -INQUIRER. contain fluorspar, for there was a piece of the limestone act on the same with an acid.-ATOMIC. SUBSCRIBER. [4895]-ELECTRICAL RESISTANCE.-Would some [4911.]-ORGAN.-Will any practical reader give me an opinion? Is there any insurmountable barrier towards tuning reeds (fitted in a common harmonium pan) in unison with organ pipes, and will the same weight of wind do? I purpose conveying the wind by a branch, from the chimney leading from reservoir to windchest of orharmonium pan is fitted for two rows of reeds. What open diap., and principal (metal) stop diap., and clarabella (wood). Another wood stop (to be added) will stops would give the softest tones? The organ has complete the affair. I look with interest for an answer to "J. W.," 4659. I have thought of placing a sounding and using the reeds with a second manual. The gan, whole requires muffling to hide buzzing? Does the contact of cloth with sounding box destroy the effect of the again. Unfortunately his letters ceased just as I belatter. Will be delighted to see "Adept" on the boards came a subscriber.-Å MERE NOVICE. [As we have said before, the last time we heard from "Adept " he stated he was very unwell.-ED.] [4912.]-CRACKED GLASS.-If a test tube, or any other glass used in chemistry, cracks from heat, an does not fall to pieces, is there any cement which will -QUILL-PEN. stick it sufficiently to use again in the flame of a lamp? [4918.]-ILLICIT STILL.-Would a still be called illicit which a person uses for making spirit for his lamp, or even to drink (please don't think I am going to), if he chose, so that he does not sell any ?-QUILL-PEN. [4914.]-M. DELAURIER'S SINGLE-FLUID BATthis battery-how the solution of neutral chromate of TERY.-Will some fellow-reader give me the details of soda and sulphuric acid is made and the elements used ?-R- N. [4915.]-SILVER COIN.-Can any correspondent in [4896]-SULPHATE OF MERCURY BATTERY.- [4897.]-GOLD LIQUID.-Will any brother reader be [4898.] NEPTUNE.-It is stated in a popular periodical that Neptune is supposed to have a ring like Saturn. Would some one be so kind as to tell me what is known on this subject ?-R. [4809.]-THE MOON.-Am I right in supposing that with a power of 300 the moon, whose apparent diameter is about 30, would appear as if it covered a space 150in diameter in the heavens?-R. [4916.]-BRASS COIN.-Can some correspondent tell me what coin this is, and the value? [4900]-CRAMP.-Would some correspondent oblige [4917.)-CHEMICAL NOTATION.-Will "Psi" kindly by informing me what is a good cure for cramp in the and same size as engraving.-SAN SEBASTIAN, legs?—J. E. Y. inform me where " The New and Old Notation of Chenistry" can be obtained ?-H. N. H. [4901.]-WATERPROOFING CALICO.-Can you in- [4902.]-VARIATION OF THE COMPASS.-Wishing [4904.]-PISTON.-I have a direct-acting vertical [4605.]-OLD MICROSCOPE.-Will "H. P." or some [4906.]-PORTRAIT LENS.-Could any subscriber [4907.] TANNING. Would Mr. Geo. E. Davis kindly give me an easy and reliable process, with numerical and manipulative details for an amateur, for estimation of tanning in commercial articles, such as sumach, &c ?-Scio. [4908.]-ENGINE VALVES.-Will Mr. Baskerville have the kindness to tell me if the cylinders and valves of stationary engines differ materially from those of locomotives, and whether the dimensions of the slide valve, steam ports, &c., given in his letter this week, are also applicable to a stationary horizontal engine?-C. H. WYNNE. [4909.]-INDIA-RUBBER WORKING.-I wish to meet with a work explaining the machinery required and the different processes india-rubber goes through in its preparation for covering cloth for waterproof garments? If any of your reader know of such a work or can give the information through your columns, I should feel much obliged. I think a good description in your paper would be very interesting to many of your readers, as the trade, so far, is looked upon as a great [4892.)-CHEMICAL ACTION ON LIMESTONE.-I have been collecting fossils in the limestone districts of Derbyshire, and amongst others I have found some limestone literally crammed with encrinite stems. In parts that have been exposed to the action of the atmosphere (or what is termed weathered) the limestone seems to have decayed and left the encrinite stems in bold secret.-AUGUSTINE. [4918.]-BICHROMATE BATTERY.-Will "Sigma' kindly tell me in what number does he explain the a copper one ?-T. J. O'C. method of fastening the copper to the carbon plates? Will a brass wire do as well to fasten to the zinc plate as [4919.]-LOWEST LINE OF PERPETUAL SNOW -Is there uniformity in the altitude of the line of perpetual snow on the peaks of mountains in the same latitude? On detached high peaks, like Teneriffe, it descends low for the latitude. On the Himalayas it is the descent is abrupt than on the north where the said that it descends lower on the southern side where The same thing is seen in America. tended table-land. descent is less perpendicular, and to an elevated exThe line of perpetual snow descends lower on Mount with its abrupt western slope, than on the peaks and ranges of the high table land of the Rocky Mountains. Hood, and other peaks of the Cascade and Nevada range, The temperature on the west sides of the great continents is milder than that on the east sides, or lower lands. Does that apply to the same degree at high altitudes ?-SABBAS. [4920.]-GEOMETRICAL PROBLEM.-The following was given last month at an examination in Germany. To construct a shall feel obliged for the solution. of the two other sides, and the radius of the circumtriangle, given the bases, the differences of the squares scribed circle.-JOHANN. [4921.]-PHARMACEUTICAL PRODUCTS.-I wish root, Cancer plant, and Sweet Gum-all American deto know the scientific names of the following:-Culver's nominations.-BERNARDIN. [4922.]-ASIATIC COIN.-Will some numismatic friend kindly describe the copper coin of which I send sketch (obv. and rev., are quite the same)?-THANKS. [4923.]-MOTION OF WATER.-Will some obliging philosophical friend inform me and those readers of the ENGLISH MECHANIC who may take an interest in such a question, why water poured into a funnel invariably runs [4924.-INSULATING.-"Sigma " said last week that round in one direction as it runs out, that direction being the same as the sun's course.-ZETETIC. he considered good paper saturated with parathue su perior to gutta-percha tissue for insulating purposes. Would the same material do for separating the tinfoil sheets of a condenser, or is a resinous substance (shellac varnish, for instance) necessary, and would not glass sheets but for their bulk be greatly superior? One question in particular I should like "Šigma's" opinion on, whether paraffine melted down from candles (that being the only form that I can obtain it in) is as good as paraffine in its unmanufactured state, as possibly it may not be so pure.-ZETETIC. supposing ample battery power available; and what is UNNOTICED QUERIES. In future, if any query remains unanswered for four Since our last J. B. Primus has answered 4281; "A 4422 [4925.]-VARIABLE STARS.-May I inquire of your courteous correspondent " A Fellow of the Royal Astronomical Society," whether any of the variable stars have been examined by the aid of the spectroscope? If so, what difference is found to exist between the spectrum of the star when at its maximum of brilliancy and that shown when at its minimum ? The only information I am acquainted with upon these points, is the case of T. Cor. Bor,, described by Webb, and which, being a "temporary star," bears, I presume, no analogy to the spectra of stars whose variations are regular. I shall feel obliged to your talented correspondent for the above particulars.-ALBERT P. HOLDEN. [4926.]-TOMATOES. Will someone inform me whether tomatoes are classed among fruit or vegetables. And where do vegetables end and fruit begin ?-E. G. [4927.)-REFILLING METAL CARTRIDGES.-Can 4428 4426 any of your readers give the method of refilling centralfire metal cartridges for revolvers ; and whether the detonating composition can be made without danger. If so how is it secured in the shell ?-E. F. N. [4928.]-NEUTRALIZING SOLUTION OF GOLD.-4436 Can any one inform me how to neutralize a solution of gold? I dissolve gold in hydrochloric and nitric acids, and wish to neutralize the solution. I have done so with carbonate of soda and with chalk, but after a few days the gold deposits in a metallic state, and at the side of the bottle there is a slight coating of gold. Can I neutralize with something that will not afterwards cause a deposit? I dissolve gold coins. What gold is best to dissolve, and where can I purchase it ?-A. B. [4929.]-SIAM AND THE SIAMESE.-Can any one give me any information as to this country and its people. What sort of climate; whether injurious to Englishmen? What the produce of the country, what animals are found there, and whether the living is dearer than here; whether any English are residents there, and if the natives have any dislike to foreigners? Also what route a person must take to get there, and about what would be the cost of a passage? This information with any more that would be useful to a person thinking of going there will oblige. I should be glad to know also the names of any authors or publishers of books treating on this country.-G. [4930.]-REFINING OIL.-Can any one tell me how to refine olive oil so that it will be thin enough for hair oil, and if olive oil is the best for that purpose?ARDASIER. [4981.]-CUTTING STONES.-Can any of your readers oblige me with a description (illustrated if possible) of a machine for cutting and polishing stones, fossils, jet, &c., and say what different tools I should require for jet to stone?-E. M. [4982.]-BIOLOGICAL.-What are the distinctive characters of living and of not-living beings; and of animals and plants?-A. T. [4983.]-HEAT POWER OF COAL.-How can I calculate the calorific power of coal from its ultimate composition?-A. T. [4984.]-BELLOWS FOR GAS FURNACE.-I shall feel greatly obliged to Mr. Thomas Fletcher, who was kind enough to give us particulars and diagram of a blast gas furnace (No. 4404, Aug. 12th), or any one else, if he will let me know what sort of bellows are required. I have made the burner, but find when I turn the gas partly down that it ignites at the inlet pipe; and should also like to know about the fire-clay furnace, how made and burnt, and any further particulars.-T. H. JONES. [4935.]-OPTICAL.-By means of a lens I project upon a white screen the image of an aperture through which a sunbeam passes; I place in the path of the beam a piece of Iceland spar; how is the beam affected? I now place across the aperture a plate of tourmaline, cut in the direction of the axis; two images of the tourmaline are formed upon the screen; describe their appearance. State also the deductions which the appearance of the images enables you to draw regarding the condition of the beam which has passed through the Iceland spar.-T. A. [4936.]-TEMPERATURE OF PROJECTILE.--A 1001b. iron ball is projected against a target with a velocity of 1,115ft. a second. Supposing all the heat generated by the collision to be concentrated in the ball, by what amount would its temperature be augmented ?-HON. SEC. [4937.]-GLACIERS AND CORAL REEFS.-Will any one explain the mode of formation of the ice of a glacier, the cause of its motion, and the geological effects produced by it? Also Darwin's theory of coral reefs, and its bearing on changes of level of great terrestrial surfaces.-HON. SEC. [4988.]-RED HEAT.-What is the action of a red heat upon the following substances, placed so as to prevent their contact with air:-Fe S2, Sm S2, Pt S2, Aug S8, A82 S3 ?-. PICKLES. [4939.]-ANALYSIS.-State exactly how you would separate from each other, and individually detect, the following constituents of a solid substance given to you for analysis:-Peroxide of mercury, soda, protoxide of iron, oxide of copper, magnesia, sulphuric acid, and hydrochloric acid.-J. PICKLES. [4940.]-MOSS AGATE.-What is a moss agate ? E. M. [4941.]-MARBLES.-How are boys taws or marbles made ?-E. M. [4942.] - -ALUMINIUM. TO "SIGMA."Would "Sigma" kindly say where the thin sheet aluminium, or aluminium wire, referred to in his description of the tangent galvanometer, may be obtained? I have not been able to get it. May I also trouble him to say if he knows where I can find any definite information as to the approximate power of electro-magnets; such as, for instance, what length and size of wire would give the greatest possible power to a core of lin, round iron, 4429 Tinning and Brazing, 478. 4430 Putting the Shot, 478. 4431 Mending Ebonite Bath, 478. 4435 Changing Red Coral to Pink, 478. 4488 Cotton Spinning, 478. 4440 4447 Wheels and Pinions of Watches, 478. 4454 Black Japan Coachwork, 479. 4455 Manufacture of Hard Soap, 479. 4463 Rotatory Motion, 479. 4468 Magnetic Battery, 502. 4469 New Dye Wood, 502. 4470 Remak Battery, 502. 4471 Insulating Varnish, 502. 4475 The Jersey Tiger, 502. 4476 Temperament of English Concertina, 503. 4480 Cow-milking Machine, 502. 4483 Deep-Sea Soundings, 502. 4486 Shorthand, 502. 4488 Mourning Paper, 502. 4491 The Telescope, 502. The following are the initials, &c., of letters to hand up Politician, Capt. C. W., Gimel, E. Putman, C. H. W. NEW HEADING.-Our new heading will appear next CORRESPONDENT.-An esteemed corre- COURTEOUS CORRESPONDENCE.-John Stout, of Morpeth, has written us a letter too long for insertion on Un courteous Correspondence. He hopes that we shall at all hazards decline to insert such letters, as they occupy space which might be more usefully appro priated, and are "contrary to a truly philosophical spirit." ERNEST PULLEN, of Malvern, says, "having derived J. B. N. should convey the information on heating ap We were THOS. CLEGG.-Your replies are advertisements. A VOLUNTEER.-Dozens of recipes for warts and chapped W. HINDS.-We never heard of a vessel where the MANX MAN. Reply on "Short-sight' Others inserted. The eye is too tender to be trifled with. J. MILLER.-Not a legitimate query, as it could not interest any one but the sender. A query and its answer should by right possess a value for at least a section of our readers, as our space belongs in a sense to all our subscribers. If only individual advantage is aimed at, the space appropriated to advertisements should be used. G. FIRTH.-See our " Answers to Correspondents "last week. TOWN GARDENING.-"Working Woman" is informed J. M. T.-See short article. New postal regulations. POWERFUL BATTERY.-"J. C."-No doubt Mr. Sprage The English Mechanic AND FRIDAY, SEPTEMBER 30, 1870. THE WORKMEN'S INTERNATIONAL EXHIBITION. or doing this, we would not be supposed to regard Reaching the stalls, exemplary of Decorative art, as definite a great many of the inventions, which we find, as we are bound to say, a disappointing are rather experiments and attempts than settled want of originality. There are medieval and results. Let us confess that we find little sym- Renaissance imitations, Greek and Roman, and pathy in our inmost hearts with men who Chinese and Indian designs, very clever and apply themselves so persistently to bicycles, ve- elaborate carvings, medallions, specimens of "ornamental fishWORLD OF SCIENCE AND ART. locipedes, tricycles, "inch multiplying motions," wrought marbles, grainings, trotting-horse perambulators." If we refer bone work," and caskets in which the extrato them in these terms, it is to remind workmen ordinary idea predominates of unnecessarily that they do themselves much wrong by mis- multiplying the pieces of which they are comdirecting a real genius which they possess. posed; but there is not much of inventive genius Compare the authors of these trifles, such as manifested. And here, on behalf of the worknursery swings and model pleasure vans, with men, we would point out the egregious misarrangethose of new plans of building, and draining, and ment of some of the collections by the Executive. fertilizing. It is not to be denied that in every What. for instance, has "a square butter or region of industry, meeting the wants and desires meat safe with water shelf," to do with "Decoinnovated every day, peculiar new paths may be rative art"? or "a portrait of Sir Titus Salt "? THIS great illustration of industry and in-struck, and so certain necessities satisfied; but In this department, as genuinely illustrated, there genuity has appreciably improved since we what we would impress is the superiority are specimens demonstrating an important adlast wrote. The objects promised for exhibition of general utility and adaptation to the require-vance since the International Exhibition of 1851, are coming in; but against one characteristic ments of life over mere ingenuity. Ingenuity when, almost for the first time since the Middle of all such displays we must protest, and we do may suggest a thousand things which are utterly Ages, and the beautiful invasions of German and it entirely in the interest of the classes repre- worthless. We are sorry to see so much of it Italian art, art became a subject of interest to sented. It is not right to declare an exhibition lavished, in response to the fatal spirit of the the English workman. We note, without the open before it is complete. The catalogue be- time, upon engines and instruments of war. At possibility of distinguishing particular names, comes a delusion; justice is not done; the public Islington there are ugly arrays of rifles, sword many common-sense concessions to the necessities are bewildered; and, inventions being sought for hilts, sword blades, gun barrels and locks, and imposed daily by that kind of wealth which in which cannot be found, a general feeling of doubt those savage matchells, which, to the disgrace of England can devote itself to a villa without being and disappointment prevails. Far be it from us our country, are sold to promote African, Mexican, competent to rear a Pisan or a Florentine palace. to suggest that this is a fault of the Islington and West Indian wars, with pin cartridges, and Wood carvings; imitation timbers and marbles; Workmen's Exhibition alone. On the contrary, all the ruffianly improvements in the means of designs for tracery windows in brick, Caen stone, it was an imperfection visible at the Hyde Park inflicting death which represent the progress of and alabaster; mullions; grainings without end, displays in 1851 and 1862; it was manifest at human nature in the year of grace 1870. With plaster centres for ceilings, and these are of Paris and at Havre, at Amsterdam, at Munich, pleasure we turn from them to a peaceful class, in- peculiar merit, as superseding the horrible old at Leipsic, at Mayence-the exhibitions never were cluding the sewing machines. There is so much trash which looks down from every suburban ready. Now, one plain principle would rectify emulation in this department, and there is so much ceiling; and a cheap method of gilding, which is all this. Let it be understood that persons de- difficulty in deciding between the various merits, likely to introduce an approach to French luxury siring to compete should, unless punctual to a that we refrain from offering anything like a into humble English homes. Mr. George Bell certain point of time, be excluded from the com- judicial opinion. It is impossible to say more of and Mr. William Manning, for their gildings on petition. But, after hinting at this topic, we the general show than that it demonstrates a plaster, deserve especial recognition. So, in gladly leave it, to dwell upon the merit, deserving practical advance on the part of most manufac- another respect, does Mr. Thomas Wallace, for to be recognized, of the mechanical exhibitors at turers; but we must instance an article displayed his painting in tempera on plaster, although we the Agricultural Hall. We have reviewed them by Mr. Cyrus Symons, "showing durability after think his own imagination sufficiently ripe to once more, with care, and find that in spite of three years' constant wear by a dressmaker." have dispensed with an imitation of the antique. eccentric devotion, in many instances, to rather Among the fiercer kind of machinery we gladly It is not unfair, while we may wish to do all curious than useful purposes, very great praise is observe the credit given directly to genuine justice to the Dutchmen, who cut wood into commanded. To the caprices we have sufficiently working men on the locomotive department of the semblances of human life; to the Austrians, who allnded. It is infinitely more pleasant to record, Midland Railway, Derby, especially with refer- cannot help pleasing, and the Bavarians, who additionally, decided proofs of constructive talent ence to the most important subjects of coupling bake their every biscuit into a fancy, to pass the on the part of our artisans. The saying that and connecting rods, and link motion. There is Italians by. They really are the matchless people. the man who makes two blades of grass grow a very praiseworthy working model of a beam- They cannot take in hand a shell or stone,grew before is a benefactor of engine with means for adjusting the throw of the they cannot undertake a single thing, from a his species, may be an old one, but is not excentric; indeed there are two, both due to Mr. medallion to a mantelpiece-without making of it the less true for being ancient. And so it is Charles S. Roe, of the Market-place, Cambridge, a joy and a beauty. The lava which runs red with mechanics devoting their rare leisure to who is, singularly enough, a jeweller. The over their southern cities is enchanted by them efforts of creation. It is consequently a pleasure Messrs. Kinsey, Norton, & Hill, of the Robin into so many shapes of loveliness that for once we to signalize their successes. The Messrs. Hyde, Hood Works, Nottingham, have a high-pressure are in despair, and feel as if where art begins of Warwick, by their improved safety-lamp, not horizontal tank and foundation engine, fitted with industry has ceased, because when there is inspiramerely rendering innocuous a development of one of Kinsey's quick-speed sensitive governors, tion there can be no toil. So leaving these bees mine-gas, or fire-damp, but giving actual warning with which may be compared Mr. James Smart's in their own golden hive, we descend to British of its approach, have done good service, and met equilibrium slide valves, and Mr. Samuel Yarrow's furniture. The Co-operative Society of Printing an important want. We noticed, with approval, cylinder diagonal oscillating steam-engines. In House-yard, Hackney-road, has an excellent also, several well-designed models of fire-escapes, the Marine Class should be specified Adamson's show. Also the Wolverhampton and Brewood a machinery hitherto most imperfect. And, in model of a canal cabin-boat; Martin's model of a Plate-Lock Manufacturing Society. Among the remembrance of many a sea experience, we give ship for the preservation of life at sea; and ingenuities of this class is Mr. James Jackson's our thanks to Mr. John Wilkins, a shoesmith, Bryant's life-buoy. Others might be mentioned, table, made entirely of paint. But we would once anent his "Model of Cabin Entrances in rough but these strike us as of peculiar excellence, and we more warn these clever men that they throw weather." Again, to Mr. George Galloway, on cannot undertake to exhaust the catalogne. The aside in waste places talents which might be account of his Plan for crossing Streets with department of tools is now nearly complete, and more usefully developed. Mr. George H. Safety." These devices may not all be practical, the show is very interesting, besides being about Brockbank's lever-escapement and check-action yet they may be indexes to future ingenuities. the most practical and useful. It comprises a for the pianoforte is one of the most admirable Taking the inventions as now multiplied in the large number of objects all professing, more or novelties in the Exhibition; it gets rid of a gross, we may separate them under two heads, less, to represent inventions, or, at any rate, im- serious difficulty, and, so to speak, renders the with a supplementary third, to which we shall provements. There are more than four hundred piano more of a familiar household god than presently refer in language of the utmost ab- and fifty exhibitors in this section, so that the ever. We think, indeed, that Mr. Brockbank horrence. An improved organ; wood-pliers, cut impossibility of rendering justice to them all has brought into the manufacture a principle of out of the solid; street-sweeping machines; will be at once apparent. We note, however, mechanics and of science which will not easily be balloting boxes; cements for setting precious Pullinger's mortising chisel, and plane which ignored for the future. The brothers Doerner, of stones; cooking apparatus; safety letter-boxes; always keeps its mouth free; Clift's ingenious Stuttgart, Würtemberg, with their hæmaostanding benches, and so forth-these are in the lock and bell combined (though this is scarcely acharnier machine, have answered to the spirit of premier list. Secondly, rat and mouse traps; tool); Galloway's stamping machine, for the day, movable sheds; street indicators; boards for month, and year, for nineteen years to come; billiard marking; inventions "for relieving a Irvin's printer's colour mill, Snowdon's nipplehorse when fallen;" horse - radish cutters; drills, and Martin's silent blowing-fans and "models for summer pillows; ""gent's ankle- lathes. In all good nature, however, we must shields"-which we confess ourselves incompetent call attention once more to the waste of ingenuity to comprehend; improved methods of showing bestowed on such a thing as "a model of the goods in shop windows; cab directors; rowing wheel seen by the Prophet Ezekiel." How did Mr. machines; and self-supplying nose-bags. Here Camp, who is a coachwright, obtain his informa are two orders, quite distinct. And now for our tion as to the size, or materials, or joinery, of this indignation. It is altogether an attack upon wonderful wheel, which, after all, is very much civilization to contrive "electro-magnetic music- upon the usual Long-Acre plan. The French, leaf turners." Why, if we had not to turn the in a kindred class, exhibit a mechanical carriage; leaves, we should never ask any one to sing! It the Italians, an olive press; the Dutch, diamonds, is the tenderest opportunity of society; and the with doll's phaetons and children's goat chaises; bending over a piece, which really means bending the Germans, gilt skates; the Austrians, a over a young lady, has given permanent happi- tailor's cutting-out machine; Bavaria, wooden ness to many an engineer. But, having disposed moulds for straw hats, and "an autobiographic of this barbarism, we proceed with our notice of press;" Bremen, "a basket sledge of reed," all the more creditable objects at Islington. In curiously characteristic of the several countries. where one the Exhibition by signalizing the actual makers of their boxes, sounding-boards, keyboards, general mechanisms, and finishings; as also have the Messrs. Wiepert and Stieglitz, of Stuttgart, who have given all the credit due to the craftsmen, from the maker of the stops to the maker of the lining-boards. If in the class of ornamental metal work we omit notice of many names, it is simply because they are so numerous, and because, as we feel sure, encouragement given to the young is sure to be appreciated by those who feel an interest in their welfare. Mr. Henry Bird, a silver-chaser's apprentice, has a pattern of embossed English ivy, in high relief on copper, which reminds us of the days when Quentin Matsys, with only one hammer and only one chisel, was set to execute that trophy which now stands, above all criticism, below the tower, and by his grave under the mighty shadows of the Minster at Antwerp. Another chaser's apprentice, we ENGLISH MECHANIC AND WORLD OF SCIENCE.-No. 288. We 2.-PLOTTING BY DIAGONALS. [SEPT. 30, 1870, line is made by the surveyor (who generally THE OFFICE REQUISITES. PENCILS, PENS, Mr. Henry Long, has three horses, with Roman vigour of action, copied from a group by Lady Dacre. Still a third silver-chaser's apprentice consists in making a triangular figure over the with a given point forward, and the drawer of the has two figures embossed from the flat. mention, merely as This is the ordinary way of plotting fields; it follows the chain) keeping the chain straight Fowler's "bowl," knocked out from a single sheet short distance of the boundary of the land to be length, sticks 1 of 10 pins in the ground. When a curiosity, Mr. Robert land to be surveyed. One or two triangles, large line. The drawer of the chain, at every chain's of iron, ornamented with a design of almond enough to extend to the boundaries or within a blossoms, birds, and butterflies, in repoussé. of course depends on the shape of the land, but standing measures 1,000 links or 10 chains. chain can check the surveyor with the backward Moreover, Mr. Norton, of Sheffield, brings an exquisite example of repoussé work, with the upper surveyed, must be used. The number of triangles all are in the surveyor's hands, the last pin leaf copper, and the under leaf iron. Wandering among these ingenuities and exercises of genius, The offset rod is a pole 10 links long divided come upon another of those remarkable devotions to which some of our working-men are into links. liable-a gether without backing." Now there is an Italian "casket made of farthings soldered toat the Agricultural Hall, who has a pair of bellows which cannot be employed to blow up a kitchen fire unless it plays at the same time, "God Save the Queen." Now, is it an unavailing repetition to tell artisans they might do more wisely for themselves than to be absorbed by the, no doubt, intense thought which must be bestowed upon these utterly unprosperous and unfruitful devices? stalls, we observe a wonderful progress made, Reaching the glass and china which, if taken fair advantage of, might open for a most remunerative market throughout Europe. It is commonly said, and it is a common us should be taken to the various hedges and land- pencil is necessary to rule the lines. Tracing paper is very useful. Tracing linen before use should be rubbed with chalk to destroyed quickly. The nibs of the drawing pen should be Paper should be hard, dry, and well seasoned. paper as the chain is on land. In the scale of 3 chains to the inch, every third figure denote the grease. In hot weather Indian ink dries a decided bow. The scales are the measurers on te lin., and each inch is divided into 30 parts, each the scale of half a chain to the inch (5 to the of which are divided by the eye into 10 links. In divided into 50 distinct divisions; each division will then represent 1 link long, not 10. If divided inch) every fifth figure represents lin., and inch. Some scales have on one side 3 chains ta an inch; on the other side, feet. feet scale along the distance in chains, feet are By laying the read off; thus a distance of 3 chains read with feet scale equals nearly 2ft. This saves calculat tions. Scales 1ft. long are sold at 1s. 6d. each offsets, at 6d., or thereabouts. mistake, that we are behind the Continent in our being generally right angles are merely measured into 10 it is again 5 chains, or 500 links to ans pl No error can along the sides, back, &c. I give an example of F 10 1 13 19 25 30 chinaware and ordinary pottery. be more deceptive, and no error has done more wrong to a national industry. True, we cannot emulate the Salviati glass-works, or the Sèvres porcelain, which is a mystery; or the Viennese vitrified ware, or the Limoges enamels; but so far as the domestic term goes, we can beat all the world. Nor in saying this do we acknowledge that in decorative glass and china the English need always fear their rivals. There are at the Islington Exhibition proofs of English skill and taste, and a feeling derived from study, which must give great hope to those who desire to see the English workman associating art with his labour. Stained and engraved glass, moresque table tops, painted china slabs, drawings in the German style, done under the glaze, terra-cotta varieties, and even articles in majolica, which the Bolognese artists have not despised. taking our leave of this great and encouraging display, we confess to having neglected certain classes. It was not within the compass of the Exhibition, properly so prepared, to include the the survey of three fields. Here A B is the base Fine Arts, of which, as here illustrated, the line; ABCD the main lines; A E and F C least said the better; or articles for personal and the test lines; G H line to offset the fence, house domestic use, or cutlery and arms, or scientific and tree, set by triangle G H D, while I J are apparatus, or fancy work, or food and raw materials. These may have rendered the Exhibition more interesting; but they did not aid in set by measurement on set lines. fulfilling the object originally proposed. In fact, LAND SURVEYING. LA AND surveying is the art of making a plan of land and estimating its extent. It is constantly resorted to by engineers, architects, and builders, and without its assistance it would have been impossible to erect and construct the large railways, bridges, viaducts, &c. It is also used by solicitors and land agents in the identification of property. To show how plans are made will be my endeavour in these papers : C 3-SURVEYING BY ANGLES. boundary of the land to be surveyed (the fewer 1. It would be impossible to set out on paper a curved line by merely measuring along it, but with a straight line running along and through it at least two points are determined; a crooked line therefore is measured by running a straight line close to it, or may be through it, and taking measurements at right angles to this straight line to the conspicuous portions of the curved line, noting measured; it is an iron chain, 100 links long, 4. THE INSTRUMENTS NECESSARY. the distances on the main line and the length of each link being 7·92in. The chain is the instrument by which land is the short lines. These short lines are called off-links is a brass hand containing 1, 2, 3, and 4 sets and may be on both sides of the line. If a fingers respectively. gentle curve is ruled from the end of each of the is made. Before commencing a survey, the chain At the end of every 10 offsets to the next offset the required line is should be measured against a standard measure, made. At 50 links a special mark An illustration of the figure S (Fig. 1.) as a brick wall, and if too long, some of the rings will show this. Having now shown how to mea- taken out. sure and offset a line I will now show how to taking a rod of 54ft. long, and measuring with it measure a figure. A standard measure is made by 66ft. (12 lengths) against a brick wall. A straight E The needle point is a fine needle fixed in a holder. A point on a line is made with it with more accuracy than a pencil. used in copying plans; the conspicuous points It is also mach being pricked through and lines made afterwards to the various holes in the paper. method is by placing beneath the plan and above Another the paper on which to be copied, a piece of blacked paper, and tracing with the edge of a small paper knife, or other fine blunt point over the various lines. The black paper is prepared It consists of a pocket-book ruled with a single by rubbing one side of a piece of thin paper with line down the centre, this represents the line. blacklead. The field-book is the book in which Offsets and figures of the fields are are entered the various measurements. placed on the respective sides. the greatest consequence to keep this book clest It is of book is commenced from the end, figure encircled on the line repre- 5 4 A sents a station or point; the figure 7 4 and is worked backwards and updenotes "to the left of." [ denotes "to the right of; wards. I give the field-book of the The 08 against the stations, put not only figure S, section 1. Some surveyors, approximate polar direction. the number of the line that joins, but the butterfly wings, all of which we will mount dry some as opaques, others as transparents. tion of wild flowers, of seeds, fronds of ferns, and Monday. We have to-day before us a collec with stellate hairs which we wish to keep. The The flower of the mallow (Malva moschata), stage of our microscope, find it to be furnished or cheeses lies before us. we make out of a piece of card and gum to the one of the green sepals, and placing it on the Taking it up we seize down at each end, to ensure its fixity. When the leaf is sufficiently thick to require a cell. This gum is perfectly dry we place our square, which slide. In the centre we fix our sepal, gamming it is of course perfectly clean, accurately on the cell, paper. This done, we proceed to paper the slide, and secure it there by a narrow strip of gummed and to neatly label it |