Part 5

_Model for Illustrating the Properties of the Ether._--A very interesting exhibit was the model for illustrating the electromagnetic and luminiferous properties of the ether, of which a detailed description is almost necessary. The model consists of a series of wheels, rotating on axes fixed perpendicularly in a plane board, and connected together by India-rubber bands. The axes are fixed at the intersections of two systems of perpendicular lines, and each wheel is connected with each of its four neighbors by an India-rubber band. Thus all the wheels can rotate without any consequent straining of the system if they all rotate at the same rate. If, however, some of the wheels are rotated through a different angle from others, the India-rubber bands will be strained. If it be desired to represent a region in which conducting matter exists, it will be represented by removing the bands from a set of wheels. Suppose the bands are removed from the regions, A and B, and from the connecting line, A B, then we can represent the charging of these regions with opposite electricities by introducing some mechanism by means of which the wheels on opposite sides of the line, A B, can be rotated in opposite directions. The model is not intended to illustrate in any way the connection between the ether and matter; indeed, one of the advantages claimed for the model is, that the study of it so distinctly emphasizes the distinction between the phenomena depending on the general properties of the ether by itself and those depending on its connection with matter. For instance, from the very case we have just considered, we get impressed upon us that it is by means of matter only that we can get a hold on the ether so as to strain it. As the object is not to illustrate the connection between matter and ether, any rough method of turning the wheels so as to create the proper strain will do well enough, as it is not the method of producing, but the nature of the strain produced that is to be considered. Having once rotated these wheels, we may replace the bands along the line, A B, and we have the state of the ether between two oppositely electrified bodies represented on the model.

It will be observed that half the India-rubber bands are strained, and that in lines running round the bodies the tight side of a band is always away from one body and next the other. This represents the polarization of the ether. The late Prof. Clerk-Maxwell defined polarization as a state in which the opposite sides of each element are in opposite states. Now, the opposite sides of each band are in opposite states--one side loose, the other tight; and so it can very well represent the polarized state of the ether. The displacement producing the polarization is due to the different rotation of the wheels carrying the band causing more of the band to be at one side of the wheels than at the other--less at the tight and more at the loose side of the pair of wheels, and this represents the electric displacement producing the polarization. The direction of this displacement is at right angles to the line of the bands that are strained, and is out from one body and in toward the other all round.

Considering the other properties of the ether that are represented by the model, we observe in the first place that during the time polarization is taking place the wheels are rotating, and that the rate of rotation of the wheels is proportional to the rate of increase of polarization, and that the direction of the axis of rotation is perpendicular to the direction of the displacement. Hence it is seen that the magnetic force is properly represented by the rate of rotation of the wheels, and its direction by the axis of rotation. The model, although simple in construction, is very useful, and its careful study will greatly assist the student in obtaining definite physical conceptions of many of the more abstruse phenomena depending on the ether.

_Prismatic Photometers._--Another exhibit was a photometer made of solid paraffin, or any other translucent substance, invented by Mr. J. Joly, of the University of Dublin. The arrangement is at once simple and effective. The instrument depends upon the fact that if a prism be cut from a translucent body, and so exposed to a source of light that one only of its faces is illuminated, the light diffused through the substance and reflected out through the illuminated faces of the prism gives it an appearance as if lighted up internally. The effect is, in fact, as if the prism itself was a source of light. Two such prisms laid together on smooth faces, and receiving light from separate sources, if placed so as to be at opposite sides of the plane of division, appear as if each was emitting light proportional in intensity to the source of its supply. The double prism has the appearance of two luminous bodies laid side by side.

When, however, the supply to each prism is brought to equality, they appear as if emitting equal quantities of light; and it is hard to detect any longer that two prisms are being observed, so completely does all trace of the plane of division disappear. An ingenious piece of apparatus invented by Mr. Joly was one for carrying out his method of determining the specific gravity of small quantities of dense or porous bodies. The method here shown enables the specific gravity to be determined whatever the density or state of aggregation of the substances, and in extremely minute quantities, with an accuracy limited only by the sensitiveness of the chemical balance.

_Telegraphing the Readings of Scientific Instruments._--Another invention of Mr. Joly was his apparatus for obtaining telegraphically the readings of meteorological instruments placed at a distance from the observer. This apparatus may be attached or adapted to the various thermometers, the barometer, rain gauge, and to other instruments placed in a mountain station, thus enabling their readings to be taken from a conveniently placed observatory. Any number of instruments may be worked with perfect reliability and certainty by the use of three wires only; the only extra piece of apparatus needed being a disk, carrying insulated contact pieces arranged round its circumference, to which the wires of the different instruments are attached. Of these three wires, one serves to put one after the other of the contacts into circuit with the home station through the second wire. By this second wire the readings are taken and the readjustment of the instruments effected. The third wire is for the indication of the contacts, and is taken from all the instruments to the galvanometer in the home station.--_Industries._

COLORED PHOTOGRAPHY.

About nine months since we directed attention to the system of colored photography invented by Mr. J. E. Mayall, London. Since that time, Mr. Mayall has further developed the details of his process, and as a result his color pictures have been much improved both as regards appearance and size, and are beautiful specimens of this new departure in photographic art. As stated in our previous notice, Mr. Mayall, after fourteen years of experimental research, has discovered the art of reproducing the colors latent in the negative of the photograph, having arrived at his discovery by the aid of spectrum analysis, which led him to the conclusion that every color in the organic world, when exposed to a suitable photographic plane in a camera, registers exact vibrations. Mr. Mayall has succeeded in producing chemical colors extremely attenuated, which exactly correspond with the vibrations in the negative. In doing this, he keeps the film alive to the smallest vibrations of light. He uses, first, lactate of iron to impregnate the isinglass film with a salt of iron capable of uniting with any stronger organic acid; and, secondly, meconic acid, which impregnates the film of albumen, and has a stronger affinity for iron than lactic acid. It unites with the iron, and forms a red film, which is in a state to receive all the lower vibrations of the red end of the spectrum, and this gives these lower vibrations a fair chance with the electric light. All subsequent processes assist this chemical march to the final end of making a print that will take up colors, which, when added, fall in their places, and there remain indelible and unalterable.--_Iron._

FUTURE PROSPECTS FOR GAS COMPANIES.[4]

By Mr. THOS. WOOD, of Sandusky.

Those who were in attendance at our Dayton meeting will perhaps recall the fact that the writer, in a paper read at that time, strongly advocated gas companies taking hold of the electric light business and running the same in connection with their gas business; you will also recall the fact that the writer suggested that gas companies should take up the incandescent electric light and fuel gas. Since that time it has been demonstrated by several gas companies in this and other States that the electric arc system can be added with success, financially, to gas companies and with satisfaction to their patrons; and the writer derives great pleasure in hearing of so many companies who have left the narrow and beaten track of prejudice and are now walking in the broad road of progression.

[4] A paper read lately before the Ohio Gas Light Association.

It is not my intention to dwell upon arc lighting now only long enough to state that, after two years of practical experience with the combination, our company consider they have taken a right step in adopting it, and that it is satisfactory in every respect. Other gas companies that have adopted the arc system can undoubtedly corroborate this with their experience. I would make this paper a continuation of the last one by now taking up the incandescent electric system and fuel gas question. That both will be introduced into every city in the United States before long by some one I have not a shadow of a doubt; and why? Simply because they are both desirable commodities in domestic economy and hygiene.

Please lay aside all prejudice, and I will show you an ideal domestic burner for illumination purposes. Now, what comprises an ideal burner for domestic use? In the first place, such a burner must not blacken our walls and ceilings, neither must it give off deleterious products of combustion; it must be a steady light, and not subject to draughts; it must not give out heat in summer, it must not be possible for inflammable goods to ignite by coming in contact with it; it must be a light that will have no ill effect if by accident the key is left open; it must be a light that our country cousins cannot blow out, neither must it be one that requires dangerous matches to ignite it, and lastly, it must be a fairly cheap light.

Now, gentlemen, if you have thrown prejudice to the winds, perhaps you can recognize in this ideal burner the incandescent electric light for domestic use. Now, if this light is an ideal one, who is going to prevent its adoption by the public? Gas companies cannot, and if they cannot no one can. So, in my mind, the wisest course to pursue is to admit what we know to be true, and proceed at once to supply the demand, increase our revenue, push out into the suburbs of our cities, sell it as cheaply as possible, and don't let others come in and take away what rightly belongs to you. If there is any money to be made in the business by others, there is still more in it for us.

For store purposes, where the hours of burning are defined, I think it better to abandon the meter system and fix a price per annum or month for each lamp, taking into consideration the hours of use as a basis for charges. For private dwellings this would not be practicable, and we would have to resort in this case to meters, or perhaps fix upon a price for furnishing the current and have the consumer purchase the bulbs or lamps whenever renewals were necessary. In this way economy would cheapen the light to the consumer. Any method that will dispense with the meter and still be satisfactory will be the one to adopt.

I cannot understand how some gas companies who have the incandescent electric system as a competitor can console themselves with the fact that it is not injurious to their gas business, even taking it for granted they are selling as much gas as before its advent. Is this a just reason why they should make no effort to secure their old patronage? I think not, for it is human nature to secure a whole loaf in place of the half, when it is possible to get it. A gas company's revenues would certainly be increased by the step, and a dangerous rival would be made profitable.

I think it is a mistake to think that by and by the people will get back to gas. Of course some will, just as gas consumers sometimes go back to coal oil; but, because a few give it up, don't let us deceive ourselves by thinking that all will do it eventually, for the incandescent electric burner is bound to remain wherever it is now in use, and will find its way to the other places where it is not now in use. "That is all very well to talk about," I hear some one say, "but what are they going to do with our prior investment?" To such I would say, push that, too. Cheapen it to its lowest point and urge its use for power and cook stoves until such time that you find yourselves able to supply gas for heating purposes of all kinds.

What difference does it make to a company whether the money expended for improvement account be coal gas benches, holders and mains, or dynamos, boilers, and wire? I fail to see the difference, and if improvements have to be made in both, so much the better--it shows a healthy demand for both branches, and should be promptly provided for.

If arc lighting is to be the light on our streets and the incandescent electric light for our stores and dwellings, shall we have to draw our fires from under our gas benches and stop making gas? This, to the writer, would be an absurd deduction, for the very reason that in nature's laboratory all these elements are placed, and gas would not be one of them if there were not some important part for it to play in the supplying of man's wants. It is for us to take the things we find in nature's laboratory and select the fittest articles for each special use; and it is reasonable to suppose that it will be only the fittest that will finally be a success. The arc light, so far as the writer has ascertained, has asserted pretty generally throughout the country its supremacy on our streets, and this in spite of all opposition from gas companies--showing conclusively that it has gained its position by the force of demand for the fittest. Incandescent electric light is just as surely finding its position and field of usefulness, and in its turn will assert its supremacy, and why? Because it has the qualifications called for in the public specifications. Some will assert that it is too expensive to come into general use, and also that it is not as reliable as gas. The first is no argument against it, for was not coal gas sold at exorbitant prices in its early days? It certainly is capable of being cheapened in the future, as gas has been, and this is one reason why gas companies should enter the business, as it is in their power to cheapen it.

As far as unreliability is concerned, it certainly looks the most serious objection; but don't be alarmed on that score, for duplicate machinery or storage batteries will eventually overcome this bugbear, and while discussing this subject don't let us forget that the breaking of a main, the filling up of a drip, a flood or explosion, or even Jack Frost, has often caused our customers to think that even gas is not very reliable.

I cannot understand what prompts gas companies as a rule to prejudice against electric lighting, unless it be they imagine the outcome to be idle gas mains and cold benches. This I think is all wrong. The largest unoccupied field to-day is the fuel gas field, and who should step in and supply this demand? Could any one do it as well as the present gas companies? We have our mains and services already laid; we have our holders, meters, and trained labor, most of us have also the necessary land to spare on which to erect the generators.

Next to the fuel gas field I think I can see another field nearly as extensive, and that is the coal oil field.

Please imagine the following picture, which is representative of the writer's belief of what a gas company will be in the near future; in fact so near in the future that before our next convention rolls around it will be a reality.

One set of officers, whose principal qualifications shall be progressiveness--their duties to be divided between electric lighting of all kinds, including electric power, fuel gas for all purposes, including gas engines; also incandescent lights off fuel gas mains.

Now let us see what the plant will consist of. One set of mains for fuel gas, from which our patrons will draw all their fuel, and also light, if they wish. Gas engines will be run economically with this gas. One set of meters only will be required.

There will be no coal gas benches as we have them now, as the method of manufacture is too laborious, too expensive and very primitive, not to say barbarous--everything now being built on the horizontal plan, requiring the greatest possible exertion to both draw a charge and stoke. The generators of the future will be on the cupola style, feeding by gravitation from the top. Native coals in all probability will be sufficiently good to make gas of. One portion of the plant will be devoted to the dynamos and engines for furnishing the electric light. Where the coal gas benches now are will be boilers, or perhaps even these will be unnecessary if gas engines be used. If steam boilers be used, they will be fired with producer gas, and the holders will become simply pressure regulators. The revenues of gas companies will be increased fivefold, if not more; the consumer will get cheaper fuel, cheaper power, and cheaper light.

Native coal fields will become more valuable, and we will not pay tribute to other States, as heretofore. The change from illuminating coal gas to fuel gas will perhaps be a slow one, owing to the conservatism of gas companies and imperfected details; but eventually it will be brought about in spite of all obstacles. If a company is operated as pictured, it will furnish arc lighting, incandescent electric lighting, and electric motors, fuel gas, incandescent gas lighting, and gas engines.

Gas will be made on a larger scale, with less dirt and nuisance, and without that laboriousness now made necessary. Valves, levers, and push buttons will displace scoop, drawing hook, and wheelbarrow, and the employees will no longer be known as "gas house terriers," but will become elevated to a higher plane. The officers of the company will also of necessity have to be more active and alert, and the rule of thumb will be at a discount. Now let us see where the gas man will be who fails to occupy these new fields of pasture green.

He will, of course, go on making coal gas in the old way; he will still wrestle with stopped stand pipes, steam jet exhausters, naphthaline, etc., and worry over how much a bushel of coke weighs. He will try to convince his customers that he knows better than they do what they want, and that anything but his gas is of no account. He will keep on cutting out items from the newspapers whenever he finds it recorded that an electric light somewhere failed to flicker.

He will still maintain that there is not a company in the country making anything out of electric lighting, and that it is only a matter of time when some fellow slips into his town and, noting things, works up an arc light company, captures the street lighting and some of our friend's best consumers. The price of gas is lowered; all kinds of patent gas burners are invested in to recapture those lost consumers; a fight ensues, factions are made in the town, and the arc light company adds an incandescent plant to the arc light, and captures more of our friend's consumers. To cap the climax, another fellow comes along and proposes to supply fuel gas to the citizens, gets a franchise, puts in pipes and services, and our friend wakes up some fine morning to find that what the electric light fellow has left him in the shape of lighting has been captured by the fellow with the fuel gas plant, who puts in the incandescent gas burners.

Evidence is cropping up all around us that tends to this change. We find manufacturers of fireclay goods now making carbons for electric lighting; we also find gas fixture manufacturers now making and selling electric wires of all kinds, besides other apparatus connected with the electrical field. Manufacturers of meters have not yet devised a meter for measuring electrical currents, but perhaps it would pay them to devote a portion of their time to studying one out. As far as the present meter business is concerned, I think, if this transformation of the gas business is brought about, the demand for gas meters would be quadrupled and the use of the larger sizes of meters would be made necessary; but if accuracy could be insured with a much smaller meter with quicker action, I think it would be better adapted for the purpose. Fuel gas, if it can be manufactured at a price at which it could be sold with profit at a lower or as low price as coal, would prove a larger field than all the kinds of lighting put together, and is certainly worth our while to investigate thoroughly. The owners of the smallest houses of our cities would become our patrons, and a small profit per thousand would represent a wide margin when taking into consideration the large amount that would be consumed.

But is the fuel gas practical, and has there been sufficient progress made to date to warrant gas companies taking hold of it with any assurance of success?

In the first place, what assurance do we require? Do we want some one to come along and guarantee us a profit of 20 per cent. on our investment if we enter the field? If so, the patentees of the different processes might just as well negotiate with the shoe maker as with the gas company. I think all the assurance we want in the premises is that with certain apparatus we can get certain results from a ton of coal (the kind of coal being specified), or that from a ton of coal we can get a certain amount of available deliverable heat units.

The balance we should be capable of working out ourselves, such as labor, leakage, cost of gas at consumers' meters, and such other data that we certainly should be more familiar with than any one else.

Of course, the fuel gas will have to have an odor, and must be delivered at a proper pressure; and proper appliances for governing supply and insuring perfect safety will have to be calculated on. In fact, the gas man must try to improve on methods adopted, and do his best to hasten the day when solid fuel in our homes shall be no more--in other words, we have to take hold of the fuel gas business in its infancy or it will get weaned away from us.

Mr. McMillin, with others, has given us some figures on fuel gas which have been verified by practical tests. For instance, he gives us as his opinion that a mixed gas is more adapted for all-round purposes than either coal or water gas alone.

From experiments made we find that from a ton of bituminous coal, making a mixed gas, we can realize as salable gas 63 or 64 per cent. of the total heat units in the original ton of coal, or about 17,000,000 heat units, besides a residue of heat sufficient to produce the steam for making the above amount.