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Proportions of steps and staircases
408
3~lechanics, P]~ysics, and Chemistry.
will be answered in the most acceptable way by the general adoption of his improvement, as certain means of avoiding the occurrence and existence of all such causes of defective boiler-plates and forge work generally, which improvements consist simply in so forming the surfaces which we desire to weld together that a free exit may be preserved to the last for the escape of the molten oxide, or scoria, until the entire surfaces of the parts we desire to weld are thoroughly incorporated by the welding property, under the action of the hammer, or rolls, as the ease may be. Fig. 5. In order to accomplish this most important and desirable object, Mr. Nasmyth forms the surfaces of his slabs convex (see fig. 5), by which most simple means a most perfect free exit to the scoria or interposing impurity is maintained to the last moment, the welding commencing at the centre part of the contact, W, and extending outwards towards the edges under the action ~ _ ~ ~ of the successive blows of the hammer, or squeeze of the roils; but, as before said, an open door is kept for the escape of the scoria, until the surfaces unite from the centre, W, to the outside edge, Z, Z, Z, Z. Here, then, by an arrangement, or formation, of" the surfaces we desire to weld we have th~ most certain and simple means of procuring a perfectly solid sound mass of iron, which, when beaten, hammered, or rolled down to whatever thickness we desire, will retain to the last all the qualities of the one sound solid mass we had converted it into by this most simple improvement--viz., giving to the surfaces we desire to weld a cow,vex form, and relation to each other. Mr. Nasmyth concluded his observations on these important subjects by an earnest appeal to the members of the mechanical section to diffuse, by all means in their power, the information which, on this as on all such subjects, he will ev-er feel the highest pleasure in communicating to the practical men of his profession, who may think fit to accept these results of an active life, which he finds so much pleasure in freely sharing with them. •
P~.oportions o f Steps and Staircases.
By J. BURGHSWATSOn*
As the following system may not be generally known to the profession, I send it, hopingthat other members may, from time to time~ communicate their ideas on points connected with our art : The late Mr. Thomas Tredgold named it to me as one to govern us i~ carrying out a properly proportioned step. He s{ated, that as it was admitted that a person of ordinary stature moved on level ground over a space of two feet at each step, and as the lifting of the foot was attended with about double the amount of exertion as advancing it forward, he considered the twenty-four inches should be so divided, that twice the rise, added to once the tread, should always ~nake up that number ; for instance; if the step was 6¼ inches rise, it should be 11~ inches tread, or 63 inches rise to be 11¼ inches. I begin with these figures, as giving * From the LondonArchitect,for September, 1S~0.
Converting Gas into Fuel for Economic Uses. 409 good proportioned steps (for I have always considered a 6-inch rise as rather less, and a 6~-inch rise as rather more, than the best proportion for general use.) But in forming a handsome staircase, where we are seldom confined either as to height or space on the plan, we may exercise our skill and judgment as we like, by having our steps 4 inches by 16 inches tread, or 5 inches by 14 inches tread ; or, in a contracted space, when a steep staircase is unavoidable, 7 or 8 inches rise × 10 or 8 inches tread respectively--all makingup the 2feet. And it will be found that the going, as it is called, will, by this rule, be about the best that could be adopted, although I need hardly say that both extremes as to rise are better avoided.
The ~qtmopyre: For Converting Gas into Fuel for Economic Uses.* Many have been the attempts and suggestions to substitute coal gas, and other combustible elastic fluids, for coal fires, as far more cleanly, more easily managed, and as giving a far more regular and quickly-ad= justable temperature. None of the plans hitherto adopted have, however, met with more than partial success, such as the application of gas burners to hot plates, boiling liquids, &c. It has been reserved for Mr. D. O. Ed= wards, a member of the College of Surgeons, to hit upon a plan at once founded on the most scientific principles, with an adaptability of being applied to every purpose for which open coal fires have hitherto been employed. It is well known that flame is a hollow cone, its exterior being formed by the evanescent particles of carbon, which being, for the moment, precipitated in a solid form after the combustion of the hydrogen, and raised to a white heat, give out light in virtue of that transient solidity. This occurs the instant before the union of the carbon with the oxygen of the atmosphere, and their conversion into carbonic acid, which forms an invisible pellicle round the flame. The heat to which this carbonaceous shell is raised is very high, but as soon as it is engendered, it is carried away by currents of the surrounding atmosphere. The possibility of arresting and detaining this heat was the problem the inventor proposed to solve. Meditation on the Davy safety-lamp afforded a clue. This lamp is a chamber, which, when its preserving agency is required, is filled with flame ; the walls are perforated with minute holes, through which air and gas freely pass, but which are impermeable to flame. The incandescent gas, in its transit through these apertures, is robbed of its heat 9 the flame is extinguished, and the heat is developed in the wire-gauze, which becomes red-hot. Here, then, was the principle; the material suitable was the next consideration; all the metals are too oxidisable, except platina, which was too expensive; a mixture of one-third china-clay, and twothirds common pipe-clay, was employed. Cylinders of various sizes, from 2 to 4 in., were formed of this matertal, perforated with numerous orifices, and having a circular opening at one end, to screw on to a No. 4 gas burner. This cylinder, or hood, is the converse of the Davy lamp, the gas being inside instead of out; and on escaping through the holes, and fire being applied, the hood, in one minute, becomes red-hot, having the From the LondonMiningJournal, No. 787. Vow.XX.--THI~DS~aiEs.--~o. 6.--D~cE~B~.U,1850. 35
3~lechanics, P]~ysics, and Chemistry.
will be answered in the most acceptable way by the general adoption of his improvement, as certain means of avoiding the occurrence and existence of all such causes of defective boiler-plates and forge work generally, which improvements consist simply in so forming the surfaces which we desire to weld together that a free exit may be preserved to the last for the escape of the molten oxide, or scoria, until the entire surfaces of the parts we desire to weld are thoroughly incorporated by the welding property, under the action of the hammer, or rolls, as the ease may be. Fig. 5. In order to accomplish this most important and desirable object, Mr. Nasmyth forms the surfaces of his slabs convex (see fig. 5), by which most simple means a most perfect free exit to the scoria or interposing impurity is maintained to the last moment, the welding commencing at the centre part of the contact, W, and extending outwards towards the edges under the action ~ _ ~ ~ of the successive blows of the hammer, or squeeze of the roils; but, as before said, an open door is kept for the escape of the scoria, until the surfaces unite from the centre, W, to the outside edge, Z, Z, Z, Z. Here, then, by an arrangement, or formation, of" the surfaces we desire to weld we have th~ most certain and simple means of procuring a perfectly solid sound mass of iron, which, when beaten, hammered, or rolled down to whatever thickness we desire, will retain to the last all the qualities of the one sound solid mass we had converted it into by this most simple improvement--viz., giving to the surfaces we desire to weld a cow,vex form, and relation to each other. Mr. Nasmyth concluded his observations on these important subjects by an earnest appeal to the members of the mechanical section to diffuse, by all means in their power, the information which, on this as on all such subjects, he will ev-er feel the highest pleasure in communicating to the practical men of his profession, who may think fit to accept these results of an active life, which he finds so much pleasure in freely sharing with them. •
P~.oportions o f Steps and Staircases.
By J. BURGHSWATSOn*
As the following system may not be generally known to the profession, I send it, hopingthat other members may, from time to time~ communicate their ideas on points connected with our art : The late Mr. Thomas Tredgold named it to me as one to govern us i~ carrying out a properly proportioned step. He s{ated, that as it was admitted that a person of ordinary stature moved on level ground over a space of two feet at each step, and as the lifting of the foot was attended with about double the amount of exertion as advancing it forward, he considered the twenty-four inches should be so divided, that twice the rise, added to once the tread, should always ~nake up that number ; for instance; if the step was 6¼ inches rise, it should be 11~ inches tread, or 63 inches rise to be 11¼ inches. I begin with these figures, as giving * From the LondonArchitect,for September, 1S~0.
Converting Gas into Fuel for Economic Uses. 409 good proportioned steps (for I have always considered a 6-inch rise as rather less, and a 6~-inch rise as rather more, than the best proportion for general use.) But in forming a handsome staircase, where we are seldom confined either as to height or space on the plan, we may exercise our skill and judgment as we like, by having our steps 4 inches by 16 inches tread, or 5 inches by 14 inches tread ; or, in a contracted space, when a steep staircase is unavoidable, 7 or 8 inches rise × 10 or 8 inches tread respectively--all makingup the 2feet. And it will be found that the going, as it is called, will, by this rule, be about the best that could be adopted, although I need hardly say that both extremes as to rise are better avoided.
The ~qtmopyre: For Converting Gas into Fuel for Economic Uses.* Many have been the attempts and suggestions to substitute coal gas, and other combustible elastic fluids, for coal fires, as far more cleanly, more easily managed, and as giving a far more regular and quickly-ad= justable temperature. None of the plans hitherto adopted have, however, met with more than partial success, such as the application of gas burners to hot plates, boiling liquids, &c. It has been reserved for Mr. D. O. Ed= wards, a member of the College of Surgeons, to hit upon a plan at once founded on the most scientific principles, with an adaptability of being applied to every purpose for which open coal fires have hitherto been employed. It is well known that flame is a hollow cone, its exterior being formed by the evanescent particles of carbon, which being, for the moment, precipitated in a solid form after the combustion of the hydrogen, and raised to a white heat, give out light in virtue of that transient solidity. This occurs the instant before the union of the carbon with the oxygen of the atmosphere, and their conversion into carbonic acid, which forms an invisible pellicle round the flame. The heat to which this carbonaceous shell is raised is very high, but as soon as it is engendered, it is carried away by currents of the surrounding atmosphere. The possibility of arresting and detaining this heat was the problem the inventor proposed to solve. Meditation on the Davy safety-lamp afforded a clue. This lamp is a chamber, which, when its preserving agency is required, is filled with flame ; the walls are perforated with minute holes, through which air and gas freely pass, but which are impermeable to flame. The incandescent gas, in its transit through these apertures, is robbed of its heat 9 the flame is extinguished, and the heat is developed in the wire-gauze, which becomes red-hot. Here, then, was the principle; the material suitable was the next consideration; all the metals are too oxidisable, except platina, which was too expensive; a mixture of one-third china-clay, and twothirds common pipe-clay, was employed. Cylinders of various sizes, from 2 to 4 in., were formed of this matertal, perforated with numerous orifices, and having a circular opening at one end, to screw on to a No. 4 gas burner. This cylinder, or hood, is the converse of the Davy lamp, the gas being inside instead of out; and on escaping through the holes, and fire being applied, the hood, in one minute, becomes red-hot, having the From the LondonMiningJournal, No. 787. Vow.XX.--THI~DS~aiEs.--~o. 6.--D~cE~B~.U,1850. 35