reduce the temperature all that is required is to open the fire door, and allow the cold air to rush direct into the flue. An extended plan of this kind might be made to suit any size of building by passing the iron flue several times underneath the flooring.-JOHN H. KIDD. [5557.]-CURVATURE OF THE RAINBOW.-Should "F.R.A.S." overlook this I beg to offer the following:The rainbow is a part of a circle which is the base of a The axis of the cone proceeds from the sun through the eye of the observer to the centre of the bow. The length of the radius depends upon the dis

cone.

tance of the drops from the observer, and the amount of arc upon, of course, the extent over which the drops fall, and the elevation of the sun. The "bow" seen in the spray of a steamboat or fountain is very small, because the base of the cone is near to the eye. 2° is about the breadth of the rainbow. The secondary bow is larger, because farther off.-M. P.

[5557.] CURVATURE OF THE RAINBOW.-In order that a dewdrop may send to your eye, after two refractions and one reflection,a bright red ray, its angular distance from the sun, as subtended at your eye, must be within a few minutes of 1889. To send you a violet ray, this distance must be about 1893; and dewdrops between these two distances will display all the intermediate colours. In other words, they must be between 401 and 42° from the Sun's nadir; that is, from the shadow of your own head, if supposed indefinitely prolonged into space. If, then, you were looking on a space thickly strewn with spherical dewdrops (for only the spherical ones exhibit these colours), all those between 4010 and 42° from the shadow of your head will appear coloured, but no others; and you will readily see that thus all the coloured ones must be within the width of a circular band 13° wide, with an inner radius of 401, and the shadow of your head as its centre. In this phenomenon indeed, which I never saw, the inverted dew-bow being referred to the surface of the ground or grass, must appear hyperbolic (unless the sun were 42° high, when it would be parabolic, and when he is higher, elliptical) though its true perspective projection is circular. Now all falling drops, whether of rain, a waterfall, or a fountain, are perfectly spherical (which is only exceptionally the case with dewdrops after sunrise) and hence they reflect you these colours, and produce the common rainbow, whose width of 12°, inner and outer radius, and angular distance from the sun, are all invariable. No two spectators can see the same bow; even your right eye and your left each see a distinct bow, for the same drop cannot send the same colour to each. There is another position between 51° and 549 from the sun's nadir, whose drops also send you the rays twice reflected from their backs between the entering and emerging refractions; and drops so situated produce the secondary bow (called in "Wessex," the water-gull) which is fainter than the primary bow, for two reasons, the greater width, nearly 30, over which it is spread, and the second reflection, in which, as at the first, some light escapes from the drop. I once saw a very rare case; a rainbow formed a minute or two before sunrise; and as neither the hill on which I stood, nor that hiding the sun from me, hid him from the 2ft. of the bow on a seahorizon, they evidently showed it to be a little more than a semicircle. "O. F." will observe that full globules of water (no matter of what size) are necessary to form a rainbow. Bubbles or vesicles, which form nearly all cloud, or mist, fog, or visible steam-cloud, as from a kettle, will not do.-E. L. G.

[5564.]WATERPROOFING SOLES.-"A Leeds Subscriber" can waterproof the soles of his shoes by applying melted suet and neat's-foot oil in a warm state. The soles must be perfectly dry. The best mode of making soles impervious to wet is to have a piece of the india-rubber canvas from an old driving belt, or two pieces of bladder, placed and sewn between the answer well.-HANTS FARMER.

outer and inner soles when made. I have found it to

[5574.]-BATTERY FOR PLATING.-For the purpose required either a small Smee or Daniell's cell would answer. Full description is given of the Smee, p. 147, the Daniell, p. 195 of last vol., or Nos. 267 and 269.SIGMA.

[5574.]-BATTERY FOR PLATING.-The best form of battery that I am acquainted with is a modification of Wollaston's, which consists of two sheets of copper, about 1-32nd of an inch in thickness, secured to a strip of varnished wood, with a groove in the centre to admit the zinc plate. The battery is excited with oil of vitriol, 1 of acid to 12 of water.-GOLDSMITH.

[5575.]-BISMUTH.-A mixture of eight parts of bismuth, five parts of lead, and three of tin is used for taking impressions from dies, &c. It is known as "fusi. ble metal." Good cliches for stereotype are made from an alloy of three parts of lead, two of tin, and five of bismuth. This alloy melts at 199° Fahr., and must therefore be used with care. Perhaps one of these might suit "Wahsrof's" purpose; if so I shall be glad. When tin and bismuth are mixed in the proportion of 24 parts of the former to 1 part of the latter, the alloy is malleable, but becomes brittle according as the bismuth is increased.-UN IRLANDAIS.

[5576.]-PHOTOGRAPHIC SLIDES.-The simplest

way of producing slides for the magic lantern, is by first taking a negative direct the size required; the transparencies can then be printed on dry plates, by contact in the pressure frame, or on wet plates, by interposing a narrow strip of thin cardboard at the extreme edge of the plate to prevent abrasion of the film; a very short exposure to ordinary gaslight is necessary. I prefer it to daylight for this purpose; being uniform, you can regulate the exposures to a nicety, with a certainty of obtaining good results; moreover, it is a pleasant and agreeable occupation for winter evenings.-MANIPU

LATOR.

[5577.]-CARBOLATES, ETC.-Phenol, or carbolic acid, has a different mode of action to any other member of the class of disinfectants, as Condy's fluid, bleaching powder, &c. Its action is not by oxidation, but by direct poisoning, no parasite yet having been known to be able to exist in a carbolic acid atmosphere. It is a direct poison to germs and fungoid matter, arresting their growth when present in minute quantities, almost homoeopathic. A mixture of calcic chloride, &c., was recommended for the preservation of starch liquor for volumetric analysis. I have used for some time now, a few drops of phenol, four drops in 100 cbc. of solution, in lieu of the above messy mixture. The solution keeps well, no fungoid matter is produced; and although phenol dissolves iodine, yet the error is not appreciable. Carbonic acid liberates carbolic acid from the carbolates.-GEORGE E. DAVIS.

[5587.]-HUGON GAS ENGINE (part answer).-To make oxide of carbon, heat powdered chalk with iron filings in an iron retort. Carbonic acid gas will also be evolved, but may be disposed of by agitating the mixed gases with limewater; which will absorb the carbonic acid, and leaves the oxide of carbon pure.-BEN:

[5589.]-EXAMINATION QUESTION.-An oxidizing agent is an element or compound which plays a part in adding oxyger to another element or compound, or causing it to combine with a greater number of radicles than with which it formerly existed; thus chlorine is an oxidizing agent ; it acts by abstracting the hydrogen from water, leaving the oxygen, which unites with the body with which it is placed in contact. Nitric acid converts ferrous oxide into ferric oxide, therefore hydric nitrate is called an oxidizing agent. A reducing agent has exactly opposite properties to the above; it has a tendency to abstract oxygen and other simple radicles. Hydrogen and sulphurous anhydride are specimens of reducing agents. When hydrogen is passed over red-hot cupric oxide, the copper is reduced to the metallic state. Ozone, the powerful oxidizer, is also a reducing agent, Aga + Oa

thus:

=

=

Ag2O + 02. and

draught wheel N, is an iron hand in which the wheel N runs. It is like an ordinary windmill, but more sails. 1f "J. H. C." gets a pie of tin, cuts it round and draws a dozen lines from the centre to the edge all round, then cut with a clipper along these marks, and then with pliers twist them half-way round, he will be able to find the plan of its working.-BUILDER.

[5594.1-REGULATOR FOR EGG HATCHER.-The following form of regulator will answer your purpose:Make it rather larger than the sketch, and immerse it

as deep as you can in the water in the boiler and just over the gas flame. When the water is at the right temperature, shut the tap No. 6, and it will then regulate the gas to the exact quantity required. The pipe No. 1 must be screwed down until it turns the gas half out, when the tap No. 6 is open, and the regulator must be kept level when once adjusted. All the parts except the tap must be of iron to prevent the mercury in the bottom acting on them. 1, gas supply pipe; 2, gas exit pipe; 3, U-shaped iron tube; 4, mercury; 5, air space acting on the mercury by expansion and contraction; 6, tap.-THOS. FLETCHER.

[5599.]-LIME CYLINDERS.-"Virgil " can make his lime cylinders as follows:-Get some pieces of chalk, file them into cylinders, place them in a crucible, cover them with sand, and expose to good red-heat in a fire; when the crucible is cold take the cylinders out, and place them in a well-stoppered bottle.-W. G. WILLIAMS.

[5602.]-MEASURING BRICKWORK.-Take the cubic feet, and reckon 306 of these to a rod. Eight ninths of the number of cubic feet will be that of "reduced feet," of 272 to a rod.-E. L. G.

[5603.]-CUTTING AND POLISHING MARBLE.

If "W. S." will send particulars as to the shape he wishes to cut his marble, the size, &c., as there are several ways of cutting it, I will forward him the necessary instructions to the best of my ability.-FRANCIS

TATE.

[5607.]-GUANO.-Guano was first brought to Europe, in 1804, by the celebrated Baron Von Humboldt, who forwarded specimens for examination to Fourcroy, Vauthe day. I can perhaps give "Guano" some more informaquelin, and Klaproth, the best analytical chemists of tion, as "Ure" has some eight pages on the above sub

R

about 4in. long, this contains the draught wheel, N; E is an iron bar, fin. thick, in which run the wheels 'A and C; F, the spindle of A and G; H, cog-wheel, with a shoulder suspended on the lin. x gin. tars I, which are lotted through the wall; J is the wire for the joint; K is the joint; L, grate and fire; M, fire and draught; N, draught wheel; X X, walls. C, which contains the

[5607.)-GUANO.-Guano was scarcely known in this country till 1841, when the late Earl of Derby, at the dinner of the Royal Agricultural Society at Liverpool, drew attention to its use as a fertilizer. The imports in 1841 were 1,733 tons; in 1864 they were 131,358 tons. Since then, owing to the use of other and cheaper manures, the imports have declined. Its value depends upon its ammonia and phosphates. -BETA.

[5608.]-T CLOTHS.-Term applied to a description of grey cotton cloth intermediate in quality and counting between a long cloth and shirting, better than the former and worse than the latter. Varies in width from 20 to 40 inches. Varies also in length and weight, but if not specially stated always means 24 yards, the original length of a T cloth.-Scro.

[5610.]-WHEAT.-The limit of cultivation depends upon the elevation of the land and the length of the summer, rather than upon mere latitude. It is a risky crop in Scotland and also in parts of Devonshire.M. P.

[5610.]-WHEAT.-In Europe the limit of cultivation of wheat is in latitude 64 N., .., in Norway and Sweden; in America the limit is in lat. 54° N., i. e., in the north of British Columbia.-S..... R.

[5611.]-STARCH. In answer to "Thomas" the "line," "cross," and "star" which he has seen are called the hilum, and the shape varies with the different starches. When seen under the polariscope with selenite stage the coloured cross starts from the hilum, or rather the four arms of the cross meet at the hilum. A magnifying power of 200 diameters often sufflees to show it, though not very distinctly, but for a thorough examination of starch granules they ought to be magnified 400 diameters.-GEORGE E. DAVIS.

[5612.]-ELECTRICAL.-The proposed substitute for carbon might be made, and could be platinized, after which the best use to be made of it would be to light a fire, for which purpose it would answer very well; for electrical use its chief value would be totest the patience and temper of the person employing it.-SIGMA.

[5616.]-BLEACHING BONE.-If "Inquirer" will steep his bone (after he has turned it or made it of the required shape) in turpentine for 24 hours, and then boilit for 2 hours in pure water, it will look yellow outside, but is really bleached and white, or whiter than

ivory; the whiteness should be brought out by holding the bone against a brush revolving rapidly (in the lathe) in whiting and water; this will fetch off the yellowness, and then if washed in warm water, and a dry and clean revolving brush be again applied, he will find it (if fine bone) very white, and having a very fine polish and gloss, and beautiful in colour.-WAHSROF.

[5618.]-GAS RETORTS.-It depends greatly upon "J. B.'s" working arrangements, which plan would be best for him. I may state that of sixteen London gas companies one only still uses iron retorts; very few, if any, the "brick-ovens," and by far the greatest number use the clay gas retort. Should "J. B.'s" works be small, he will probably have no exhauster, and other requisites for the proper use of them. As to the ultimate result, there can be no doubt of the superiority of clay retorts over iron ones.-BEN G. [5622.] PRESSURE IN BOILERS.-"W. H. F." does not say what thickness of plate his boilers are made of, but if they only be fin. thick, they will bear 20lb. per square inch with safety; but I would recommend him to get a competent man to examine them for fear there may be any faulty place that can only be detected by a careful examination.-W. H.

[5630.]-AQUARIUM.-Cover the bottom with a piece of slate neatly fitted to size, and bed it on Portland cement, or after thoroughly drying cover the oak with a coat of marine glue. The water should never require renewal, and only the slight addition necessary to replace the loss by evaporation, say once in three months. The best plants are Valisneria spiralis and Anacharsis alsinastrum. These planted in a bed of sand and pebbles Sin. thick will keep the water perfectly bright throughout the year.-E. J. COLLINGS.

[5630.1 AQUARIUM.—I should recommend the bottom to be glazed inside to make it watertight. If charcoal is placed below the sand, and if some pieces are also placed in the aquarium and held down by stones, the water ought not to want changing more than once a month. The charcoal held down by the stones should be changed once a fortnight. This is the way I carry on mine.-C. H. H.

[5630.]-AQUARIUM.-A layer of cement at the bottom will stop the leak. I had a large one, the water in which was changed about once in three months. Any intermediate accumulation of dirt was removed by a siphon. Frequent syringing and watering through the fine rose of a long spouted pot is very beneficial; the object being to carry down as much air as possible to the fish. After these periodical cleansings, the plants were replaced several days before the fish, thus enabling & good stock of oxygen to be accumulated in the interval. Stratiodes Aloides I found the most useful plant, as by the removal of the old plants when too large, or of the offsets when too numerous, to a tank out of doors, and interchanging them when required with the aquarium, a succession of plants in a growing state could always be maintained-an important consideration. Starwort too, is a good distiller of oxygen, and should float on the top in short lengths, where it will arrange itself like duckweed.-AMATEUR.

[5631.]-SILVERING SOLUTION.-I do not know Hasselby's preparation, but the following will produce satisfactory results:-Cyanide of potassium, 2oz.; water, 20oz.; oxide of silver, foz. Dissolve and apply with sponge or rag fixed to a stick. N.B.-It is very poisonous.-BETA

[5634.]-COLOURING BRASS.-A lacquer will, I think, meet the requirements of "T. R. G." The basis of lacquers is a solution of the resinous substance called seed-lac in spirit of wine. The spirit ought to be very much concentrated in order to dissolve much of the lac. To a pint of the purified spirit about 8oz. of powdered shellac are to be added, and the mixture to be digested during the same day with a moderate heat. The liquor ought then to be poured off, strained, and cleared by settling. This clear liquor is now fit to receive the required colour from certain resinous colouring substances, the principal of which are gamboge and annotto; the former of which gives a yellow, and the latter, an orange colour. In order to give a golden colour, two parts of gamboge are added to one of annotto; but these colouring substances may be separately dissolved in the tincture of lac; and the colour required may be adjusted by mixing the twojsolutions in different proportions. To make a small quantity, "T. R. G." has only to take proportional decimal parts of above specified quantities. S:

..... R.

[5635.]-PHOTOGRAPHIC.-"A Would-be Photographer" does not state whether the spots are transparent or opaque. It is somewhat difficult to advise, as they are caused by such a numerous variety of circumstances. One half the ENGLISH MECHANIC might easily be filled by stating the causes and the remedies for pinholes, comets, and spots.-MANIPULATOR.

[5636.]-MICROSCOPE." Zetetic" will find a sketch of the body of a "compound binocular" in a recent number of this journal; the same, minus the second body and "Wenham's prisms," will serve roughly as his model. Were I going to construct myself a microscope, I should purchase my lenses, lin. and fin. objective, and an A Huyghenian eyepiece, of some good maker. A 10in. length of brass tube would serve as the body of the microscope, and should be from in. to lin. diameter, excepting at the ends, where its diameter must of course coincide with that of the objective and eyepiece. Along one side of the tube the rack for the motion must be firmly fixed. The stand may be of any form that meets the wishes of the constructor, but a heavy iron plate, with a solid upright rising from it on opposite sides, would be most easily devised. Into the upper end of these fix cones to carry the frame into which the rack motion is to work. The rack on the body should slide into the frame for several inches and fit truly, the pinion of the rack working smoothly and without lost time into the rack. The frame may be carried below the cones, and be adopted to receive the stage plate and the mirror. But as I said to a previous queriest five minutes' sight of a microscope would give more insight into its construction than a long article. "Zetetic's " query respective fittings of polariscope is answered in query 5597.-H. P., H.

[5637.)-ELECTROTYPE.-"An Eighteen Months' Subscriber" puts a question particularly unflattering to me, seeing that it indicates that after the perusal of

my papers describing in detail all the "Galvanic Machines" fit for his purpose, he is still so much in the dark as to ask for the means of constructing an electrophorus of all things for electrotyping, a description of it and its proper use having also been given. Reply 5574 will give him what he wants.-SIGMA.

[5638.]-ELECTROPLATING WITH PLATINUM. -A solution of platinum may be made by dissolving the metal in two parts of hydrocloric acid and one part nitric acid; the dissolved mass may then be evaporated to crystallization, dissolved in distilled water, then add a small lump of cyanide, which will percipitate the solution first, and afterwards redissolve it. It must then be filtered, and is ready for use. Weak battery power must be applied.-GOLDSMITH.

strips of wood ths by 3-10ths, and make 17 small frames that shall just go in, a trifle under 6in. by 6in.; in the niddle of the two sides a groove must be made to take a strip of wood that goes across the drawer to prevent the front row of slides running over the back row when the drawer is pulled out. The ledges for the drawers are made of strips of wood sufficiently thin to allow of easy sliding in the grooves, i.e., a trifle under thin. They are ths wide, and are glued on the bottom of the frame. of the frames, and glued on to the ledges, this forms the A square of cardboard is then cut, the size of the inside bottom of the drawer; the strip across the middle is then glued in, and another thin strip across the front to hide small bone knob completes the drawer. The lowest one the joints of the sides and bottom. The addition of a runs on the bottom of the cabinet, so the ledges must [5638.]-ELECTROPLATING WITH PLATINUM. only project on the inside. The outside edges of the -"W." will find it rather a difficult undertaking, un- cabinet may now be rounded off, the whole well sandless he is used to electro-deposition. The solution is papered, hinges and a small lock put on, and it is ready made by dissolving chloride of platinum in distilled for French polishing or varnishing, after which a small water; the strength of the solution I use is 5 penny-brass handle at the top makes it complete. This will weights to the quart of water, but a pennyweight more hold 204 slides in the horizontal position, and is geneor less makes no difference. When the chloride is rally charged from thirty shillings to two guineas by dissolved, add a solution of cyanide of potassium opticians. I hope I have made myself sufficiently clear gradually until the precipitate first formed is dissolved. to "Rhus Cotinus," if not he must please take as my The solution is now ready for use, and now also come the difficulties; the solution must be used warm, but I tools, I know less about the terms they use in their excuse, that though I know a little about carpenters' can give no according to the battery power, the proportion of the temperature, as it constantly alters work.-FELLOW OF ROYAL MICROSCOPICAL SOCIETY. surfaces of anode to goods to be platinized, strength of solution, &c.; the best plan is to make it lukewarm to The battery power must be weak, and this commence with-above all not to begin too hot. is too much power the platinum is deposited as a black where the cause of failure generally lies, as if there is powder. Try and avoid this by letting the platinum anode just touch the surface of the solution and gradually immerse till the metal begins to deposit. Experience will alone teach him in the matter of heat and battery power, and he must expect a few failures at first. He must not forget that the anode is not dissolved, so it will be necessary to have a strong solution of chloride of platinum, which must be added to the solution to keep up the strength, and if the chloride is not freely dissolved add a small quantity of cyanide solution till it does dissolve.-W. G. WILLIAMS.

[5639.]-NEPAULESE HAIR-DYE.-The best and the safest hair-dye that will give you the most satisfaction and the least injury is two drachms of extract of camomile to one gill of warm water; keep in bottle and dip the comb in and pass through the hair, minding there is no grease on the hair.-H. T. TAYLOR.

[5640.]-ELECTRIC CLOCKS.-Length of pendulum rod, 11in.; length of beat (maximum; three manganese cells), in.; weight of "bob," 30oz.; size of magnets, 3-10in.; size of coil, lin.; distance of pillars, 2in.; number of oscillations with one impulse, 65.-GEO. Fox.

[5641.]-CABINET FOR MICROSCOPE SLIDES.The drawers of microscopic cabinets are usually made only about in. deep, as it is considered better for the slides to lie on their backs than on edge: moreover, any one can be selected at a glance. I should have the drawers 104in. by 64in. inside and about in. deep. They should be lined with velvet or cloth. There must be a full on either side of it. A drawer of this size will hold division across the middle of each drawer leaving Sin 20 slides, or 40, if thin enough to pack one on top of an

other. They are sometimes made with racks to hold the glasses on end; in which case the drawers should be Itin. deep. The rack is made of mahogany as in the cut; a is a front, b an end view.-A. S. C.

[5641.]-CABINET FOR MICROSCOPE SLIDES.

Any one having some knowledge of tools and a little knack in handling them, will find the following a cheap and easy method of making an exceedingly neat and efficient cabinet. Procure a piece of pine, as free from knots as possible, which when planed and squared up shall be gin. thick and 8in. broad. From one side of this take out a square piece, ths broad and 3-10ths deep; this is to form the shoulder for the door; and from the opposite side a similar piece which need not be so broad, say 3-10ths each way, this is for the back. Then with the saw divide into four pieces of such lengths that when put together the height inside may be 8 in., and the breadth 6fin. Of course the length depends on the method of putting together, whether dovetailed, mitred, or otherwise; the former, though more troublesome, is much the neatest. Next take the two longest pieces which are to form the sides, and on each draw lines across where they will meet the bottom and top. The space between these lines, 8in., must be ruled into 17 equal parts of in. each, in. above each line rule another, and make fine saw cuts through them all; then take out the wood between the closer lines to the depth of in.; these are the grooves for the drawers to slide in, and therefore care must be taken that the opposite sides closely correspond, that the grooves are all the same depth, and are well smoothed with sand paper on the inside. Fasten all four together, by dove tailing or otherwise, and glue in a piece for the back the depth of the shoulder which has been made. For the door take a piece of wood, the thick and of a length and breadth corresponding to the opening, so that it may shut up flush. To prevent warping a cross piece should be put on the top and bottom in the usual way. A neater plan, however, and one entailing very little more trouble, is to have a glass door, made thus:-Take a piece of wood ĝin. thick and 1fin. broad, and from the edge plane away in. so as to leave a shoulder for the glass, cut four pieces at an angle of 45° and mitre it, as for a frame; glue together and make a saw cut at each angle into which insert a thin bit of hard wood, glued to make it more secure; fit in a square of plate glass and fix by means of a fillet also glued. To make the drawers, prepare some

[5641.]-CABINET FOR MICROSCOPE SLIDES.Make a cardboard box, with a fall-down front, like sketch, and cover with coloured calico. Then make a lot of stiff pieces of cardboard to lay flat inside, sew some flat black elastic, such as is sold by the drapers, on it to slip your

slides under. I have found this answer admirably; my boxes are 7lin. long, 8in. wide, and 2in. deep, in the clear. Each card holds six slides, and you can multiply cards, slides, and boxes as desired.-GEORGE HOS

KING.

Paris mould of the same. First rub the seal with bees[5643.]-IMPRESSION OF SEAL.-Make a plaster of wax, then run some plaster of Paris on the seal; allow it to get set before removing the seal, then run some block tin on the plaster, this will give you a facsimile of your seal.-H. S. TAYLOR.

[5644.] TOUCH PAPER. - Soak thoroughly good brown paper in a strong solution of saltpetre; when well dried it is fit for use.-W. P.

[5644.]-TOUCH-PAPER.-In my young days I made excellent touch paper, by soaking coarse paper several days in a strong solution of saltpetre and water, and allowing to dry gradually.—Amateur.

[5647.)-RULE WANTED.-"The force exerted by a 101b. weight falling from a height of 80ft." can only be defined as an impact of 800 foot-pounds. It cannot be "expressed in pounds" (which are units of pressure) any more than in gallons or acres. A pressure is one kind of magnitude, and an impact is another-as distinct as distance and bulk, or weight and area; so that the question of Fred Roe might as well be, how many pounds make a yard ?-E. L. G.

[5647.]-RULE WANTED.-The term "footpounds" has been introduced to express in a convenient form the lifting or falling force of 1lb. the height of lft.; thus the force exerted by 101b. falling lft., or 1lb. falling 10ft.. is equal to 10 footpounds, therefore 10 x 80 = 800 footpounds.-C. W. STIDSTONE.

[5648.]—RULE MARKING.-For a rule or scale to measure any length within its own to hundredths of an inch, the readiest plan is to divide every inch into tenths, and have a sliding vernier, either nine or eleven tenths long, divided into ten. I never heard of 100tha of an inch being marked on rules, but this may be a misprint in the latter part of Fred. Roe's query for 10ths.-E. L. G.

[5661.]-SHEEPSKINS.-Make a small quantity of whitewash with quicklime: brush a thin coat of this on the flesh side of the skin, roll it up with wool side out, and leave for two or three days. By that time you can pluck off all the wool, which you will find quite loose. Then, to preserve the pelt, if in summer, spread it out to dry in the sun; if winter, rub it well on both sides with salt, roll up tightly with flesh side out, and put away till wanted.-J. N. TRAYLER.

[5664.]-IVORY SHAVINGS.-These are a most valuable manure for plants in pots; perhaps the best that can be used.-T. F.

[5670.]-NEURALGIA IN THE FACE.-To any one liable to this complaint I think the great desideratum to be attained is to keep from catching cold. I was formerly much afflicted by it, but since I commenced a system of bathing my chest and shoulders every morning with cold water I have not had a single attack.-SERGIUS.

[5670.]-NEURALGIA IN THE FACE.-Quinine, 16

grains; chloric ether, 2 drachms; tincture of iron, 2 drachms; water, 8 ounces; dose, one tablespoonful three times a day. For outward application, soak half an ounce of cayenne pods in a noggin of spirits of wine, over-proof strength if it can be obtained, or as strong as possible, and rub the affected part.-MANCUNIAN.

[5671.]-GRANITE POLISHING.-To prevent the water freezing during the process of polishing granite surfaces, I would suggest to "Scotch Granite" to try a little methylated spirit mixed with the water, or any spirit that does not freeze, excepting at very low tem peratures. I cannot conceive he can experience much difficulty from his lubricating oil thickening through cold, for very few movements or revolutions of his machinery would suffice to soften as much as would lubricate the journal. -FERAD-ARTHO.

[5766.]--SEALING-WAX.--I have dropped some sealing-metallic substances and aerolites that occasionally fall, wax on the velvet cover of my portable writing-desk. some remarkable specimens of which are to be seen in Can any reader inform me how to remove it without in- the British Museum ?-CASTOR. juring the velvet ?-OZOKERIT.

[5767.] - WATER PIPES.-Which would pass the greater quantity of water, a pipe 24in. in diameter, or two pipes 12in. in diameter ?-THERESA.

[5768.]-POISONED WHEAT. Can any of our chemical readers tell me with what substance Barber's poisoned wheat was impregnated? I found it the best poison for destroying mice that was ever invented. I cannot purchase it now at any price. It used to say upon the packets that it was not hurtful to man or the larger animals.-T. P. JONES.

[5769.]-DIVIDING PLATE.-What thickness should the dividing plate for a 5in. centre lathe be? Supposing it to weigh Glb., would it have any perceptible retarding effect upon the speed of the lathe when used for ordinary turning? Are they ever made so that they can be removed at pleasure ?-T. P. JONES.

[5770.]-ALABASTER.-How can I clean some alabaster masonry which has lost its colour through smoke? Also, Bath stone, plain and gilded, which is almost black

from the same cause?-OLD SUBSCRIBER.

[5771.]-VALUE OF COINS.-What is the value of a two-sovereign piece of George IV. in perfect preservation? Also of the gold rupees coined at the siege of

Mooltan ?-OLD SUBSCRIBER.

[5772.]-SMALL SILVER COIN.-Can Mr. Henfrey say what a small silver coin of early date and bearing the following impressions is likely to be?

On one side

a rude shield, with a bend charged with pellets and surmounted by a coronet; on the reverse, service with fleur de lis.-OLD SUBSCRIBER.

[5773.]-METAL INLAYS.-Will some brother reader inform me what process is required to fasten on to wood ornamental pieces of brass, such as are seen in

laid on inkstands and boxes ?-AN AMATEUR.

[5785.]-MUSICAL BOX.-I have a musical box which plays dance music too fast to suit the dancers; the "fly" is not capable of adjustment, and there is not room for a larger one to go round. I should be glad if any competent person would inform me whether it would materially increase the resistance to replace the present fly of two fans with one having four fans, which of course would rotate in the same space, or whether making the fans concave, instead of flat, would do it ?-FLY.

the ellipse equally without that would be a great advan tage. I have an interpolating index for plate, and tangent screw, and wheel on chuck.-F. NORTH.

[5797.] VIBRATIONS OF THE CHROMATIC SCALE.-Would the "Harmonious Blacksmith" kindly furnish me with the number of vibrations for the chro matic scale, taking 252 for the C natural, and increasing for the diatonic in the ratios of 9-8, 5-4, 4-3, 8-2, 5-8, 18-4, 2, and especially the exact distance between A sharp and B flat 7-F. NORTH.

[5798.]-VIOLIN PEGS. How to turn and finish them, and what chucks or fixings are necessary; will some one say and oblige ?-F. NORTH.

DRAUGHTSMAN.

[5787.]-ALUMINIUM AND ITS ALLOYS. — I shall be extremely obliged to any one who will kindly inform me of the various alloys with aluminium? Fownes says very little on the subject, but remarks that some of the alloys promise to be very useful, and only alludes to that with copper. Can any one tell if a solder for the metal in question has been discovered; if so, what are its ingredients, and with what flux is it used? I have wasted any amount of time and patience in order to discover it, as I have been positively told none is at present known, and that were there one the metal would be more generally used. All ornaments, &c., that I have scen made thereof are riveted.-CHIPS.

[5788.] ROSE-COLOURED PROMINENCES ON THE SUN.-What is the meaning of incandescent hydrogen? Does it mean hydrogen red-hot, or burning as it combines with some other gas ?-M. P.

[5789.]-THE INTER-SIDEREAL ETHER.-Have any observations been made that would lead us to suppose the ether to be subject to the attraction of the sun or planets? Does it, by its behaviour towards the transmission of light, discover anything resembling tide motion; or, to put it more plainly, are there any aberrations known to astronomers which could be attributed to disturbances in this cosmical fluid ?-M. P.

[5774.]-THE MAGNETIC POLES.-I should feel obliged if "F.R.A.S." would kindly give the most recent opinions as to the magnetic poles. The researches of Gauss and Hausteen, I believe, resulted in the supposition of two or more poles. Faraday expressed an opinion that the hypothesis of the existence of magnetic readers inform me as to whether the quality of gas makes [5790.] QUALITY OF GAS. Could any of your poles at the geographical poles is unsatisfactory, and that the phenomena of the dipping needle tend to one following reason: A meter supplying 200 lights, in a any difference in the measurement? I ask for the of two things; either that the magnetism is simply the certain number of hours indicates 14-587ft. The gas is result of the induction of electric currents, or if a terrestrial magnet really exists (which is highly impro- year when the gas was better, made from half coal and not good, being made almost altogether,from coal. Last bable) the poles must be close together near the earth's half cannel, and better purified than at present, the same centre. As it is probable that the earth is an electro-meter, supplying the same number and size of lights, inmagnet, the magnetism of which is caused by electric dicated 9-897ft, in an equal length of time. There is no currents, and that these are produced by change of leakage in the pipes, they having been carefully tested. temperature from rotation, and which brings the I should be glad to know how many feet per hour an different parts successively under solar influence, the magnetic poles are therefore likely to be in the neigh- ordinary No. 2 jet will consume.-T. S. J. B.

bourhood of the terrestrial, where the opposite magnetic

influences chiefly reside. May not the magnetic poles (considering the recent aurora) include in varying density the whole spaces included in the Aretic and Antarctic circles?-INQUIRER.

[5775.]-BRAZING STEEL.-Can any of your readers kindly inform me how I can braze bright steel without scaling, and what solder should I use? I should be glad if our editor would give space for "Jack of all Trades'" porous cells.-W. H. L.

[5776.]--WOOLLEN RAGS AND SHODDY.-Tons of woollen rags are collected. Could any of our readers give a description how they are manufactured into shoddy, where there are any mills for the purpose, and what is about the value of woollen rags per ton.-J. NEW

BURY.

[5777.]-LATHE HEADSTOCK.-I am much obliged to J. K. P." for the valuable information he has given respecting division plate, &c. I am so very dissatisfied with the headstock now on my lathe that I intend to try and make a new one, back-geared, and mandrel running in steel collars. Would "J. K. P." favour me with a few particulars as to suitable dimensions for a 54in. centre headstock, and (if not too much to ask) a hint or two on the grinding of the hard steel collars? I intend to make the mandrel of iron, with two steel cones to slide on, and be fastened by lock nuts. How is it his mandrel with 1 taper cones does not jam ?-BIERLALA. [5778.]-OAK GRAINING.-Can any reader inform me how to grain oak colour, what paints or colours are used, and how to mix and apply them?-T. E. COPE.

[5779.]-COIL.-I have a small induction coil which has three sets of binding screws; one set for battery wires, one for secondary, and another for primary wires. I get no shock out of the primary, and only a very small one out of the secondary. What is the cause of this? I use two Smee's battery plates 6in. by 3in., perhaps the battery power is insufficient. The coil is 4in. long

by 1 in. thick.-A SUBSCRIBER.

[5780.]-MAGNETIZED NEEDLES.-TO "SIGMA." -It is recommended that the needles be hardened and then tempered to a blue before magnetizing, or operated on in the soft state, and will "Bigina" tell me whether the coil, page 2, is wound all in one direction?COLONEL B.

[5781.]-WORKING BATTERY.-Will any of your readers answer me the following?-A is a battery, B the wire which at one part forms a square, C and D electro-magnets. Part of the current passes through each side of the square and works the magnets, but I want the current only to work the magnet C, and by reversing the current to work D instead. How can I do it ?-COLONEL B.

[5788.)-SHEET LEAD AND ROMAN CEMENT.Will some kind render communicate a method of making a permanent joint between sheet lead and Roman cement? It is required for a large malting cistern, subject to such extreme pressure as to cause leakage at the angles. I propose inserting sheet lead if I can insure a perfectly reliable junction with the present lining of Roman cement.-MALTSTER.

[5783.]-BORING GUN BARRELS.-I am much obliged to "Gun" for his information, and I wish to ask him why a muzzle-loader should be bored different to a "breech-loader." I should like to know how a 21in. barrel muzzle-loader should be bored.CHASSEPOT. [5784.] -AEROLITES.-Will some correspondent kindly inform me the source or supposed origin of

[5791.]-VARNISHING DIAGRAMS, ETC.-I should be glad to learn the best composition for varnishing diagrams and plans prepared in water colours, also the best method of applying the same ?-JAMES SMITH. [5792.]-STRAIN OF ROOF.-I should be obliged if "R. H." would kindly give an easy method of finding the strains of a roof with curved and arched top, and with a curved and straight herod.-X + Y.

[5793.]-LATHE.-Many thanks to "J. K. P." for his prompt reply to my query. Perhaps he will as kindly answer me the following: Does he mean that I shall want 55, 60, 70, 80, 90, and 100, for every of an inch, and decrease in diameter? I cannot see how I can do without a carrier (as I understand him), the two 50's will both lathe; but how will a 60 and 30 gear without a carrier, gear when the slide rest is put on the bed of the accompanying sketch will show how I wish to gear up be a fixture? The my lathe, the number 3 being to the left hand when standing in front of the lathe to work.-TOM BROWN.

because the slide-rest must

screw. A, to carry two between the 50's. B, end view of 150 teeth on spindle, 2 = carrier, 3 = 50 on leading the same to fix to lathe bed.

[5794.]-ARITHMETIC AND ALGEBRA.-TO "E. L. G."- Would E. L. G." say if Barnard Smith's to teach himself from? I have a great admiration for "Arithmetic and Algebra " is a good one for a beginner "E. L. G.'s" profound mathematical knowledge. hints as to how to proceed would be received gratefully by-Scio.

Any

HAND.

[5800.]-VERTICAL DRILL.-Could J. Moseley or some other kind correspondent send me particulars of a vertical drill. I am an amateur, and do not wish to go to the expense of purchasing what I could make myself. Would not a spring do to press the drill bit on the work? I would like a drawing with full particulars as to size.-T. G. BARLOW.

[5801.]-POWER OF CYLINDER.-What is the power of a cylinder 4 in. long and 2in. in diameter ?—T. G. B.

[5802.]-CLOCK WHEELS.-I should like to know how the wheels of clocks are made, viz., how the teeth are cut.-THOS. G. BARLOW.

the exact nature of the disturbing influence exercised [5803.]-COMPASSES IN IRON SHIPS.-1. What is on the compass by an iron vessel? Is the vessel itself polarized by the action of the terrestrial magnetism, and has it then a tendency to reverse the poles of the needle ? 2. Would not this influence be least felt in the middle of the ship (neutral line)? 8. Would not the compass be most affected when the ship was sailing in the lines of the magnetic meridian, and least when sailing at right angles to it? 4. What means are adopted to modify or overcome this influence?-A SUBSCRIBER. [5804.]-DRESSING SHIRTS.-J. Gormley's answer knows how to polish. No girl does, unless she has been to Starch," 4745, is quite correct, viz., to any one who instructed, though she had a ton of wax. A polished tried again, and I cannot do it Do help me somebody — shirt looks as if it had been enamelled. I have tried and

A SISTER ARTIST.

(reply 5466), tell me the size of the opening in the inner [5805.]-AMERICAN MOTH TRAP.-Will "A. S. C.” end of the glass funnel?-C. H. H.

[5886.]-TIN CAN.-Would "E. L. G." have the kindness to explain how he makes the area of a circle equal to 2, whose radius is 2, that is decimals 1-4142136Also, how he makes the area of the side of the same which calculation shows the area to be equal to &1416011 ? cylinder, height 2, equal to 4, when calculation shows it to be 4-4428950. For what reason "E. L. G." has introduced a second cylinder,radius v3 to prove his statement is, to "H. W. R." at least, quite unintelligible. "H. W. R." acknowledges his error in the dimensions of the tin can, owing to having inadvertently omitted a

coefficient of a fluxion.-H. W. R.

[5807.]-FISHING NETS.-Is there any machine for making a fishing net speedier than the needle and mashboard?-GUILLAUME.

[5808.]-HYDRO-ELECTRIC MACHINE.-How can

I make a hydro-electric machine ?-GUILLAUME.

and standards; bed, 3ft. 8in. long, 4in. broad, 1țin. [5809.]-HEADSTOCK.-I have an iron planed bed between bed. Will J. K. P." or some other subscriber S. D. tell me what height of headstock would best suit it ?

[5810.]-DAMP-PROOF PAPER.-Can any of your readers inform me where to obtain paper which will be unaffected by constant damp, and in a saturated atmo sphere will always be firm and pleasant to write upor with a black-lead pencil ?-M. C.

[5811.] -MAKING WOOD PARTITION SOUNDPROOF.-Can some subscriber furnish me with the information for making a wood partition sound-proof, in an economical manner ?-WHISPER.

[5812.]-SOLUTION FOR CAST-IRON BATTERY. -Will Mr. James Howard kindly inform me whether the solution which he recommends fo the cast-iron battery can be used in the single-fluid bi bromate battery, or whether the nitric acid would pro luce too great action on the zinc ?-H. W. CURTIS.

[5813.]-TAPPING DIES.-Would any reader tell me the best way to tap the dies of a Whitworth stock? I have tried a great many different ways but have failed this difficulty solved for me.-PROUDFOOT. to get the right one. Shall be much obliged to have

[5814.] WILDE'S MAGNETO - ELECTRIC MACHINE.-TO" SIGMA."-I have made a small Wilde's magneto-electric machine, as nearly as possible according to the instructions contained in Ferguson's" Electricity;" the magnet armature 5in. long, the other 9in. A small steam engine I have made drives both armsscarcely get any signs of life from the large armature. tures about 1,200 revolutions per minute, and yet I refuse to traverse the wire of the electro-magnets, I get sparks from the maguet armature, but it seems to coils on each leg, and the wire is No. 16. One cell of a although insulation is complete, and there are but five the magnet armature be arranged for quantity, with inSmee's battery charges it considerably more. Ought armature prone to leap over moderate insulation? sulated copper plates? or is the induced current in the Finding myself foiled in Wilde's machine I subsequently made one of Ladds, as described in "ours," Vol. VI, page 338. But the same difficulty occurs again. In fact, I can get no signs of life at all from this, althong h I took the greatest pains in every part. Of course, I feel very disappointed after all my expense, and months of labour, and should feel truly grateful for any suggestions as to the cause of my failure or for the remedy.

INFELIX.

[5815.] HARMONIUM STOP AND PEDALS. Would "The Harmonious Blacksmith" or "Adept " inform me the best way of adding the Voix Celeste stop to a five action-stop harmonium? also the best way to make and attach a two octave set of pedals to the same? -VOIX CELESTE.

[5816.]-SOFT SOAP.-Will some kind reader of your valuable journal inform me if the common soft soap of commerce can be used for washing purposes; if so what addition must be made to it to make it so available?— C. P.

harp? The publishers of pianoforte music are numerous, but I don't know a harp-music publisher.-T. S. H. [5835.]-BLACKING.-Can any of your readers inform me how the material in which cakes of blacking are packed is manufactured? It is, I believe, called "skin," but I imagine it is paper. It so, what kind of paper is used, and how is it prepared?-F. GRAY.

[5886.]-MOIST WATER-COLOURS.-I shall feel greatly obliged if any correspondent can inform me how the moist water-colours, sold in the shops in small porcelain troughs, are prepared ?-F. GRAY.

[5817.]-WATER WHEEL.-Will one of "our" correspondents oblige with the relative horse power of an overshot water-wheel of 30ft. diameter and 2ft. 6in. breast? The water is conveyed from the hills, about a mile, into launders, which towards the wheel are 22ft. from the ground, the launder over the wheel being lft. 6in. in width and in depth 8in., the water rising [5837.] TO MILLERS. Thanks to J. Downes, therein according to the season of the year. I should "R. R. S.." and "C. J." for answering my query adstate that the wheel now works at a distance of 1,650ft. from its centre, by wire rope and rods, a set of pumps dressed to millers (5504) as to the power required to drive 10in. diameter and 135ft. deep. My object in making five pair of stones on maize. I must say to "R. R. S." the inquiry is to judge whether I have sufficient power that I have been in America, and wish to know from him to work a second set of pumps in addition to the above, if he refers to Page and Prentice's Mill (so called in at, say, 2,000ft. from the wheel, and also the lowest depth America). In this mill the under stone is the runner. of the water required for either and both of the above in Can he tell me who are the makers, in Norwich or Ipsthe launder over the wheel to give the necessary force ?wich, of the mills he mentions? They are fixed in a frame of wood, or metal, and driven from underneath, and -J. W. M. [5818.]-DEXTRINE.-For what is dextrine used ?-oblige-BENSON. [5838.]-ALARUM BEDSTEAD.-Can you or any of my fellow readers inform me where I can obtain an alarum bedstead, or furnish a description thereof with sketch? One appeared in the Exhibition of 1851; and in 1853 a patent was applied for by a Mr. Savage, but the specification gives no details.-W. WATSON.

B. E. LODDY.

[5819.]-GUN QUESTION.-Why does a gun kick more if loaded with small shot when fired than with large shot or a bullet ?-SERGIUS.

[5820.]-GLANDERS.-Would "King," who kindly answered my last query on the above, please say if there has been any known instance of cure. I have heard it repeatedly stated that none ever recovered.SERGIUS.

(5821.]-CASTING.-I wish to make some small brass castings, say of standards, bearings, &c., to a model engine, but do not understand how the patterns are made and put together, and what is the best thing to mould them in. If any reader would furnish information on this subject they would greatly oblige-PUFFING

BILLY.

[5822.]-EXPANDING EMERY BIT.-Will "Gun" send a diagram of an expanding emery bit, one that can push into the part I wish to bore, and by turning it round bore that particular place? I don't like a steel bit because it is apt to ring the barrels.--CHASSEPOT.

[5823.]-AIR.GUN.-Would any of your correspondents give an explanation of an air-gun; how to know when sufficiently charged with air; whether it will send shot; and the best way of putting shot into the barrel? Is there any fear of bursting the breech ?-An answer would oblige.-A GAMEKEEPER.

[5824.]-MAGNESIUM LIGHT, ETC.-Whether has it ever been made available for dissolving views, and if so, how best applied? The Drummond, or oxyhydrogen light, requires the use of so many articles for its development and support, as well as there being great danger attending the manufacture of the necessary gases. I wish for some intense luminator for shedding a brilliant light, equal to fifty candles. What would be the cost of an electric light of this power capable of being charged for two hours' duration?-ARTIFICIAL LIGHT.

Give

[5825.]-REFRACTION:-Will some practical astroguard? How is the correction for renomer help a beginner? fraction made? I am directed, in adjusting my equatorial, to make two observations of the polar distance of a star with the declination circle east and west, to take the mean and deduct so much for refraction. Now I understand the effect of refraction to be to raise the apparent place of a star above the trae, and therefore it seems to me that the correction must be by adding to the observed polar distance. If some one, instead of laughing at my ignorance, will help me out of it, he will greatly oblige-A BEGINNER.

[5826.]-VACUUM GAUGE.—Will any reader explain how it is that my vacuum gauge indicates so irregular? Sometimes it is 131b., and in an hour or two perhaps 11 lb. or 12lb.: sometimes it is 131b. one day, and 12lb. another. A few hints on the vacuum will oblige-A YOUNG MECHANIC.

[5827.]-DISSOLVING SILK IN CUPRO AMMONIUM.-Will any one kindly oblige by giving the proper method to pursue for the purpose of dissolving silk in "cupro ammonium?" I have tried a watery and ammeniacal solution in vain.-AMICUS.

DOMESTIC RECIPES.

(From the Food Journal).

[5829.]-IODINE IN MILK.-Would some kind reader inform me what should be the result of ten drops of iodine in half a wine-glass of milk ?-B. E. LODDY.

5880.-HARMONIUM.-Would "Adept" or the "Harmonious Blacksmith " tell the best way of constructing an harmonium, with twelve stops for the full organ, and about five or six for a swell, with two octaves of pedals? Also how to tune the harmonium.-LOVER OF MUSIC. [5831.]-SILVERING BLOCK-TIN.-How to silver a block-tin figure ?-J. N. TRAYLER.

[5882].-TINNING COPPER.-I shall feel greatly obliged to any of my brother readers who will furnish me with instructions how to tin copper articles, such as This the cups used in the "sulphate of lead" battery. query has been previously asked, and appears to have got overlooked somehow.-UN E COSSE.

Would

[5833.]-ELEMENTARY MATHEMATICS. — Mr. Biggs, or any other gentleman, have the goodness to give some exercises on the first book of Euclid, suit able for a science class for mechanics and others, and hints as to their solution.-T. 8. H.

[5834.]-HARP MUSIC.-Would the "Harmonious Blacksmith "give information as to a publisher of popu lar and fashionable tunes arranged for single-acting

it on the dish and serve.

BEE STINGS.-The fear of being stung deters many from bee-keeping. This is excusable in those whose peculiar physical organization is such that much pain and inflammation result; but such are in the minority. The danger of being stung is not so great as is geneThe bees seem to know the timid, rally supposed. while those who approach and handle them with courage, carelessness, and confidence, can go among them without annoyance. It may be an annoyance to the novice to be stung, from the pain and swelling, but in a few seasons the system will become so accustomed to the poison that but slight swelling and no pain will result. The pain is more in the imagination than reality, and the sooner the beginner becomes so selfpossessed as to receive the sting of a bee as he would the scratch of a briar, the sooner he will succeed as an apiculturist, for if he is for ever in terror of his bees he will not give them the attention they need, and will never attain the best results.

SULPHUROUS ACID.-The value of sulphurous acid gas as a disinfectant has been established by many and crucial experiments, and is generally admitted. This agent (says the British Medical Journal) is specially recommended by medical officers of health. There is a want of convenient methods of applying it, and especially of applying it in a limited space and to a definite and measured degree. Mr. John Gamgee has called attention to the convenience of employing it as disengaged from an alcoholic solution. Cold alcohol will, he states, take up three hundred times its bulk of gulphurous acid gas; and where, for example, it is des red to saturate a box of clothing with this gas it is sufficient to drop a certain quantity of its saturated solution of alcohol into the floor of the box, and a large definite quantity is set free by the evaporation. The suggestion is one of importance, and seems to us worthy of attention. The solution of sulphurous acid in alcohol could easily, and probably with advantage, become a general article of pharmaceutical commerce for medical and sanitary use.

5206

Engraving, 95.

5209

Polish on Cast-Iron, 95.

5211

Fret-Sawing, 95.

5213

Heating Surface of Boilers, 95.

5221

Horizontal Angles, 95.

5223

Art Night Class Examinations, 95.

5229

Self-Cocking Revolvers, 95.

5230

Harmoniums and Organs, 95.

5234

Gilding, 95.

5240

Refrigeration, 119.

5244

Mounting Buterflies' Tongues, 119.

5246

Dissolving Ivory, 119.

5217

Copying Paper, 119.

5248

The Ripening of Pears, 119.

5219

Varnish for Clay Pipes, 119.

5251

Pattern on Linen, 119.

5255

Heating by Hot Air, 119.

5256

Brewer's Truck, 119.

5258

Wire Drawing, 119.

5233

Size and Power of Boiler, 119.

5269

The Manganese Battery, 120,

5270

Enlarging Photographs, 120.

5278

Abyssinian Blue, 120.

5282

Paper Foliage, 120.

5283

Verge Escapement, 120:

5285

Splitting Selenite, 120.

5290

Damaged Barometer, 120, 5292 Percussion Action for Barometer, 120. 5293 Cement for Lether, 120.