Electric fan

“ The application of the electric fan has up to now done little more than substitute a thorough draught, the which of all discomforts an Englishman will least tolerate. In the circulars of ventilating engineers you find the statement that their particular fan will renew the air of a room so many times, say six times, per hour. This statement is not true. What is true is that sufficient air is extracted whose volume would fill the room six times per hour, and that, of course, an equal quantity of air is sucked into the room ”

“ Currents of air much less forceful than those of steam in a turbine are generated by the electric fans of our shops and offices. When their vanes move as the hands of a clock, a breeze comes toward you; reverse their motion and the stream blows away from you. Place such a fan in the side of a box otherwise closed; driven in one direction the vanes force air into the box; driven the opposite way the vanes remove air from the box. Powerful currents of this kind, such as stream from a Sturtevant blower, are used for blast furnaces and the largest steam installations. ”

“ The older method of creating air currents was by means of furnaces, but this method, while very effective, is expensive and dangerous. In using this system a furnace is built near the outlet of the air shaft, the combustion of the fuel creating the necessary draught. But in the nature of things this furnace is a constant menace to the mine, besides being an extremely wasteful [253] expenditure of energy. The modern method of ventilating is by means of rotary fans, the electric fan having practically solved the problem. ”

“ Overhead are flags and bunting, while light is supplied by rows of big electric lamps depending from slender wires. Placed in niches at intervals along the walls are electric fans, the incessant whirling of which supplies a pleasant draught, almost a breeze, in fact, in the sultriest of weather. ”

“ One necessity, however, is the provision of motive power, very small though it be, to work the fan or otherwise promote a draught.
Electric heating is, however, the method which will probably take precedence over others in all those cases where systems are tried on their actual merits apart from sentiment or usage. The wonderful facility afforded by the electric heating wire for the distribution of a moderate degree of warmth, in exactly the proportions in which it may be needed, gives the electric method an enormous advantage over its rivals. ”

“ There is no direction in which a more pressing need exists for the distribution of power in small quantities than in regard to the ventilation of private and public edifices.
The circular fan, placed in the centre piece of the ceiling and controlled by an electric switch on the wall, is the principal type of apparatus applicable to the purposes of ventilation. As electric lighting of dwelling-houses becomes more common, and ultimately almost universal within cities, the practice will be to [Pg 204] arrange for lighting and for ventilation at the same time. ”

“ Where electricity is available as a motive power for driving the fan, some modification in the views expressed as to the curvature of the pipes and system of installation can be allowed. In a red lead plant, for instance, it may be desirable to have the pipes leading to the sifter or packing machine with sharp angles, so as to prevent tendency of such heavy dust to collect in them. The electric current allows a fan to be installed at any point desired; and if applied with knowledge that the increased friction due to an acute angle has to be overcome, the result may be quite satisfactory. ”

“ Still, perspiring crowds constantly watched the workmen, who struggled with the overpowering heat, although Cosmo had erected canvas screens for them and installed a hundred immense electric fans to create a breeze. ”

“ In this way the temperature is everywhere kept very nearly even. Electric fans are ready for use in case of any sluggishness in the circulation, and in summer are also used for sending cooled air into the stack. ”

“ Electric fans for home ventilation are also used, and in the domestic operations where a small amount of power is required (as in driving sewing machines, boot cleaners, washing machines, mangles, knife cleaners, “vacuum” cleaners, &c.) the electric motor is being largely adopted. The trend of affairs points to a time when the total demand from such domestic sources will greatly exceed the demand for lighting only. The usual charges for current to be used in domestic heating or power operations vary from 1d. ”

“ Some of the motors are self cooled which also does away with wear and hot boxes.
There are various kinds of fans which may be used. Those which change their direction in process of revolution are good. Some think they are better than the one-direction fan, and maybe, where the fan is used alone without other attachments such as purifiers and blowers, this style may be more efficient. ”

“ How quickly a spoon inserted into a hot cup of tea becomes uncomfortably hot, though the hand can be held very close to the liquid without feeling more than a gentle warmth. And we all have noticed that the very least air-gap in an electric circuit effectively breaks a current capable of traversing miles of wire. If the current is so intense that it insists on passing the gap, it leaps across with a report, making a spark that is at once intensely bright and hot. Metal wires are to electricity what speaking tubes are to sound; they are as it were electrical tubes through the air and ether. ”

“ Instead of a platinum wire, a fine thread of carbon is brought to a very high temperature by the passage through it of the electrical current, in which condition it gives out light. All that you have to do to light up is to connect your lamp with the battery. The reign of the match, as you see, so far as incandescent electric lamps are concerned, is a thing of the past. We need no match to fire it. ”

“ In fact, the incandescent lamp operates upon this principle; the carbon filament is traversed by a current of a strength sufficient to heat it to a point where it becomes intensely luminous, and sometimes, through accident or otherwise, the current becomes strong enough to melt the filament, and then the light goes out. In an electric motor it is not necessary to raise the temperature of the wire to the melting point to do serious injury; in fact, if the heat is sufficient to char paper or cloth, the machine will be rendered useless until suitable repairs are made. ”

“ The electrical glow is therefore produced by the constant passage of electricity through a small portion of air in which the tension is very high, so as to charge the surrounding particles of air which are continually swept off by the electric wind, which is an essential part of the phenomenon.
The glow is more easily formed in rare air than in dense air, and more easily when the point is positive than when it is negative. This and many other differences between positive and negative electrification must be studied by those who desire to discover some thing about the nature of electricity. ”

“ Gas light is more difficult to manage than electricity, for there is always the cumbersome tube and the necessity for adding mechanical accessories before a good clear light is secured. Gas lamps are hideous, for some obscure reason, whereas there are hundreds of simple and excellent wall fixtures, drop lights and reading lamps to be bought already equipped for electricity. The electric wire is such an unobtrusive thing that it can be carried through a small hole in any good vase, or jar, and with a suitable shade you have an attractive and serviceable reading light. ”

“ Lamps not to be run too bright. For the sake of economy, it is well not to run the lamps too bright. Without giving the lamps the maximum current a very good light can be obtained, and they will last all the longer. I need hardly say that there is a medium in this as in everything else, and it does not look well when a candle is placed alongside of an electric lamp to enable a person to read or write in comfort.
All this time the dynamo is running, and we must feel the bearings occasionally to see if they [39] are keeping cool. No trouble with dynamo if oiling is attended to. ”

“ It is plain, therefore, that on its merits as a conveyer and storer of power the electric current is preferable to compressed air. The heat that is generated and then dissipated in the compression of any gas for such a purpose represents a very serious loss of power; and it is altogether an insufficient excuse to point to the compensation of coolness being secured from the expansion. Fans driven by electric motors already offer a better solution of the ventilation difficulty, and the advantages on this side are certain to increase rather than to diminish during the next few years. ”

“ Where a fan installation is necessary, the loss of draft in the fan connections should be considered, and in figuring conservatively it should be remembered that a fan of ample size may be run as economically as a smaller fan, whereas the smaller fan, if overloaded, is operated with a large loss in efficiency. In practically any installation where low temperature gas requires a fan to give the proper heat transfer from the gases, the cost of the fan and of the energy to drive it will be more than offset by the added power from the boiler secured by its use. ”

“ The vanes of the fan, when set in motion by electrical or some other motive power, produce a powerful current of air, which can be regulated according to requirements. As in the last plan, the aspirating influence of the fan may be exerted over a system of rooms, by means of connecting tubes. ”

“ When the coil is set to work, the molecules of the air are rhythmically attracted and repelled. As the force with which they are repelled is greater than that with which they are attracted, it results that there is a repulsion exerted on the surfaces of the fan. If the fan were made simply of a metal sheet, the repulsion would be equal on the opposite sides, and would produce no effect. ”

“ In the distant future, electricity will be used for electric lighting only as subordinate to other uses to which it may be applied such as heating houses, taking place of stoves for cooking, being used as a substitute for the steam engine. In fact the motor is rapidly becoming of as much practical use as the electric light. ”

“ ELECTRIC HEATING The light of the electric incandescent lamp is produced by the heating to incandescence of a thin filament of metal or carbon, and the heat itself is produced by the electric current forcing its way through the great resistance opposed to it by the filament. In such lamps the amount of heat produced is too small to be of much practical use, but by applying the same principle on a larger scale we get an effective electric heater. ”

“ This is called the multiple circuit, and it is obvious that the entire amperage produced by the dynamo will not be required to pass through each lamp, but, on the other hand, each lamp takes only enough necessary to render the filament incandescent.
This invention at once solved the problem of the incandescent system and was called the subdivision of the electric light. By this means the cost was materially reduced, and the wiring up and installation of lights materially simplified. ”

“ Now when the condenser is fully charged it discharges through the spark gap and then the electric oscillations set up surge to and fro through the closed circuit. As a closed circuit is a very poor radiator of energy, that is, the electric oscillations are not freely converted into electric waves by it, they surge up to, and through the aerial wire; now as the aerial wire is a good radiator nearly all of the energy of the electric oscillations which surge through it are converted into electric waves. ”

“ In an apparatus for lighting gas by electricity, the combination of a wire through which a current of electricity is passed, actuating mechanism for letting on the gas, and electro-magnet electrically connected with said wire, and armature operated by said electro-magnet, mechanism actuated by said armature, breaking the circuit at the burner tip, and producing there an electric spark or sparks for lighting the gas, the whole operating automatically. ”

“ Although there is a variety of ways of producing electricity, from the rubbing of a piece of sealing-wax on the coat-sleeve to the vast engines employed at large central lighting-stations, yet here we will consider only such methods of producing the force as are in practical use on a moderate scale. The current for electric lighting may be obtained either from chemical batteries or from machines termed dynamos. ”

“ Where the electric light came in as a great and lasting boon was in the lighting of the interior of the air chambers and air shafts of the large pneumatic caissons while in the process of sinking. The absence of all smoke or filth due to oil lamps of whatever description, the facility with which they could be moved, changed, put up or taken down, was of incalculable advantage in places where breathing even the purest air was a task of some discomfort and difficulty, and here, therefore, the electric light reigned supreme. ”

“ If the tube be exhausted of air, a non electric lining in contact with the wire is not necessary; for in vacuo, the electrical fire will fly freely from the inner surface, without a non-electric conductor: but air resists its motion; for being itself an electric per se, it does not attract it, having already its quantity. ”