The ingenious way in which Mr. Crompton has utilised the heating effect of electric currents for cooking purposes has no doubt been admired by most of you at the Crystal Palace Exhibition last year; and when we remember that these cooking utensils consume fuel only during the time they are actually in use, and that they can be put in and out of action at a moment's notice, we cannot doubt

Diagram 3.

PLAN

Rivet-heating.

that these and many other obvious advantages will facilitate their introduction in spite of the figures, as to cost, given by the scientific data.

Of late the transmission of power by electricity has occupied a very prominent place in the public interest, and the project of utilising the force of the Niagara Falls at distant towns is as closely discussed as the plan of constructing long railways on which trains are to run at fabulous speeds.

As you will hear a discourse on electric railways in three weeks from to-day, I will not take up your time with this branch of the subject, but will rather draw your attention to the distribution of power by electricity from a central generating station. Before entering further into this, let me remind you that the earliest magneto-electric machines were used nearly sixty years ago for the production of power. I will mention only Jacobi's electric launch of 1835 as an example; it must, therefore, be considered altogether erroneous to ascribe the invention of the transmission of power to an accident at the Vienna Exhibition in 1873, when, it is said, an attendant placed some stray wires into the terminals of a dynamomachine; it began to turn, and the transmission of power was first demonstrated.

As a matter of fact, Sir William Siemens once informed me that his brother Werner was led to the discovery of the dynamo-electric

principle by the consideration that an electro-magnetic machine behaved like a magneto-electric machine, when a current of electricity was sent into it, viz. both turn round and give out power. It was, of course, well known that a magneto-electric machine produces a current of electricity when turned by mechanical power, and Werner concluded that an electro-magnetic machine would behave in the same manner. We all know that he was right, but I relate this circumstance only as a further proof that the generation of power by electric currents had been a well-known fact long previous to the Vienna Exhibition.

Another well-known instance of transmission of power to a distance is furnished by the magneto-electric A B C telegraph instruments, where the motion at the sending end supplies the currents necessary to move the indicator at the receiving station.

As an illustration of the distribution of power by electricity I will briefly describe some radical alterations that have been made at the works of Messrs. Siemens Brothers and Co. by the introduction of electric motors in the place of steam engines. The diagram on the wall shows in outline the various buildings in which work of different kinds is carried on with the help of different machines. Electric motors are supplying the power, sometimes by driving shafting to which a group of tools is connected by belting, and sometimes by being coupled direct to the moving mechanism. Each section of the works has its own meter measuring the energy that is used there, and all of them are connected by underground cables to a central station, where three sets of engines and dynamos generate the electric current for all purposes.

There are two Willans and one Belliss steam engines, each of 300 I.H.P., coupled direct to the dynamos and running at a speed of 350 revolutions per minute.

Room is left for a fourth set; but, including some auxiliary pumps and the switchboards for controlling the dynamos and for distributing the current, the whole space occupied by 1200 horse-power measures only 32 by 42 feet.

Close by are the condensers and three high-pressure boilers, which have replaced some low-pressure ones formerly used for some steam engines driving the machinery in the nearest building.

The advantages that have been secured by the introduction of electric motors may be briefly stated under the following heads:

1. Various valuable spaces formerly occupied by steam engines and boilers have been made available for the extension of workshops, and these are indicated on the diagram by shading.

2. By abolishing to a great extent the mechanical transmission of power a considerable saving is effected in motive power, which is especially noticeable at times when part only of the machinery is in use.

3. As the electric motors take only as much current as is actually required for the work they are doing, a further saving is effected and VOL. XIV. (No. 87.)

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at the same time the facility with which the speed of the motors can be altered without their interfering with each other, presents a feature that is absent from mechanical transmission.

4. The big steam engines, being compound and condensing, produce a horse-power with a smaller consumption of fuel than the small high-pressure steam engines scattered throughout the works.

5. The numerous attendants of the old steam engines and boilers have mostly been transferred to other work; only a few of them are required at the central station, and one or two men can easily look after all the electric motors used in the various parts of the works.

Elsewhere, equally favourable results have been obtained by the introduction of electrical distribution of power, and in this respect I beg to refer you to a paper read before the German Institution of Civil Engineers by Mr. E. Hartmann in April of last year, and to a paper read by Mr. Castermans before the Society of Engineers in Liège in August last, in which he compares in detail various methods of transmission of power, of which the electrical one was adopted for a new small arms factory.

We may, therefore, take it for granted that the advantages alluded to above have not resulted from local circumstances at Woolwich, but that they can be realised anywhere by the adoption of the electric current for distributing power from a central station. At first sight this result appears to be of interest only to the manufacturer, but the development of this idea may lead to far-reaching consequences when we consider that cheap power is one of the most important requisites for cheap production. You can see on the diagram that the various buildings are separated by roads, and we can easily imagine that in each of them an independent owner carries on work, so that the diagram represents part of a manufacturing town.

While power was generated by steam engines, the cost of producing one horse-power varied a good deal in the different parts, and the various owners could not have obtained their power on equal terms, those possessing the largest steam engines having a distinct advantage. This inequality is done away with altogether when the power is distributed by electricity, as the current can be supplied for large or small powers at the same rate per Board of Trade unit. It is therefore clear that the establishment of central stations for the generation of electricity on a large scale will bring about the possibility of small works competing with large works in quite a number of trades, where cheap power is of the first consideration.

Another circumstance favouring small works is the diminution of capital outlay brought about by the employment of electric motors. Not only are the motors cheaper than boilers and steam-engines of corresponding power would be, but the outlay for belting and shafts is saved, and the structure of the building need not be as substantial as is necessary where belts and shafting have to be supported by it.

A commencement has already been made in this direction by the starting of electric light stations, where the owners do all in their power to encourage the use of the current in motors in order to keep the machinery at their central station more uniformly at work.

The introduction of electricity as motive power will apparently

present a strong contrast to the effect steam has had on the development of industries for the reasons already stated; and, in addition, there are many cases where the erection of boilers and steam engines, or even of gas engines, would be inadmissible on account of want of space or of the nuisances that are inseparable from them. Motive power will, therefore, be available in a number of instances where up to the present time no mechanical power could be used, but the work had to be done by manual labour or not at all.

You may have noticed that I have confined my remarks hitherto to the case of distributing electricity over a limited area, but that I have not yet discussed the question of transmitting power to a great distance.

Theoretically we have been told over and over again that the motive power of the future will be supplied by waterfalls, and that their power can be made available over large areas by means of electric currents. As a prominent example, the installation is constantly mentioned by which the power of a turbine at Lauffen was transmitted over a distance of 110 statute miles to the Frankfurt Exhibition with an efficiency of 75 per cent. No doubt this result is very gratifying from a purely scientific point of view, but, unfortunately, in practical life only commercially successful applications of science will have a lasting influence, and in this respect the Lauffen installation left much to be desired.

On the one hand science tells us that the section of the conductor can be diminished as the pressure of electricity is increased, and it appears to be only necessary to construct apparatus for generating electricity at a sufficiently high pressure so as to reduce the cost of a long conductor to reasonable limits. On the other hand, experience shows that at these high potentials the insulation of the electric current becomes a most difficult problem, and for practical purposes difficulty means an increased outlay of money. As an illustration of the difficulties encountered in the employment of high-tension currents, I can demonstrate to you that many of the insulating materials employed with success for low-pressure currents break down under the strain of high-pressure electricity.

For the purpose of these experiments the current of electricity delivered by the street main at a pressure of 2400 volts is diverted to a large transformer placed on the ground-floor, and from there it is led through a twin cable to this room at a pressure which can be increased up to 50,000 volts. This twin cable was used in 1891 at the Frankfurt Exhibition, for conveying a current of 20,000 volts from the main Exhibition to the Exhibition on the Main, and when it was returned to the works, it was found that the insulation was as good as when it was first manufactured. A sample of it lies on the table, and by its side the sample of a concentric cable designed for a current of 2500 volts. A comparison of the two shows in a striking manner how elaborately high-tension cables have to be insulated.