company has an electric pannace designed on the lines of the Admiralty steam pinnaces. It is 36ft. long, 7ft. beam, with a maximum draught of about 2ft. It is built in pine with oak stem, stem and stern posts, and is bright all over. The accumulators, 50 in number, are arranged in teak boxes under the seats, and are so placed as to be easily removable when necessary. The whole is so strongly built that by suitable arrangements the pinnace can be slung on davits with all electrical equipment ready for use. The cells can be charged either with the pinnace slung in the davits or moored alongside the ship. The motor is much more powerful than those usually supplied by the company for use in the launches on the Thames and at Windermere, and a speed of 11 miles per hour can be obtained for some three to four hours. Since these boats are principally used for shore purposes, speed and power have been considered

high-speed engine-this advantage will be specially felt when there is a tendency to racing of the propeller; and the whole of the electric details have been so well thought out and proved by actual experience, that there is no fear of a hitch. Since the motor and accumulator are all arranged beneath the floor and seats there is more room and greater comfort for passengers, and the carrying capacity of a given size boat is increased by about 50 per cent. The small torpedo boat running on the lake at the Naval Exhibition has been equipped by one of the company's launch motors, and the company have just received an order to build and equip a second boat of similar dimensions. The headquarters of the company's boat department are at Platt's Eyot, Hampton, where different-size launches can be seen and inspected by those interested. There are many other interesting things to be seen at

of more importance than duration of run. For shore and harbour pinnaces electricity possesses many advantages over steam, and they no doubt will be largely in demand before long. These launches are ready for use at a moment's notice, and possessing none of the disadvantages of steam as regards dirt, smell, and heat, commend themselves to the consideration of all. One of these pinnaces, 40ft. long, 7ft. 9in. beam, and 2ft. draught, with a handsome teak cabin, is now being built by the T. G. Electric Power and Traction Company to the order of the Naval Department of the Russian Government; it is expected that this launch will give fully 11 miles per hour. The company have demonstrated the sea-going properties of these pinnaces; they find them to have a very steady motion even in a fairly high sea, and the centre of gravity is so well placed that the rolling is little. The motor having no reciprocating parts, runs more smoothly than a

OG.E.P.T. Co.Ld. O Switch and Fuse.

this stand, but we cannot enumerate them here; a visit should be made.

The Telautograph Again.-Prof. Elisha Gray, the noted electrician of Chicago, will give a public exhibition in July of the latest invention, the telautograph, which (says a New York telegram) is destined to revolutionise telegraphy. Prof. Gray perfected the invention in 1889, after working on it for seven years, but kept the secret until the patents were secured. The instrument not only transmits the message a long distance by wire, but reproduces at the receiving point a perfect facsimile of the message as written. Pictures and diagrams may also be transmitted. The instruments will be manufactured at Highland Park, a suburb of Chicago, and branch lines will be established throughout the country.

practical part of the work. In this direction the difficulties encountered have been neither few nor simple, but for the most part have been successfully overcome, so that half a dozen or half a score of engineers would readily provide plans for the lighting of any town in the kingdom-plans which if carefully carried out would lead to perfectly trustworthy and satisfactory lighting.

VESTED INTERESTS.

The decision with reference to the BirmingBirmingham electric tramways and the telephones shows conclusively that the telephone companies will fight under the aegis of "vested interests" to obtain the monopoly of " earth return." The man in possession is a most difficult individual to deal with. Morally, his right may be objectionable, but practically he laughs at all opponents. The "earth" as a return seems naturally to come under the head of common property, just as the air we breathe; but currents do interfere with each other, and no doubt heavy currents, such as are used in tramway work, or in lighting, cannot use the same earth as telephone or telegraph currents. The case stands thus: In many places telephones have been installed, and in the majority of instances, when installed, the earth is used as the return part of the circuit. The telephone companies are private adventure concerns, and whatever profits arise go into the hands of shareholders and are not common property to the whole community like telegraphic profits. A part of the profits is paid in the shape of royalty to the Telegraph Department, and so may be looked upon as a benefit to the community, but otherwise, as we say, the adventure is one of a purely private character. Tramway work, electric lighting, electric transmission of power, are also private adventures, and from the moral point of view these adventures have just as much right to use an "earth return" as the telephone.

In no case, however, is an earth return better than a metallic return, and it is only used to save money; and this, so far as telephony is concerned, is usually saved at the expense of time and temper. The best telephone circuits are those wholly metallic. It is argued, however, that initial saving is of the utmost importance in the early stages of an industry, and that the development of telephony would be greatly retarded by insisting on the use of metallic circuits Some eminent telephone engineers dispute this, and contend that in all instances the complete metallic circuit is the best.

At Birmingham the tramway company desired to use the earth as a return, but the telephone company objected, and has won the day, in that the tramway company will have to incorporate in its Bill a clause to use a return wire. The shareholders of the tramway company, being mostly local people, are rather nettled at this decision, and a good deal of correspondence has taken place on the subject in the local Press. It will be seen, however, that the

Street

The question of rapid transit has been one that has been agitating the minds of engineers and municipal authorities in New York not less than in London itself. The overhead railways above the streets have made their unpleasantness abundantly felt in spite of their convenience, and further rapid transit was hardly to be looked for in this direction. railways with overhead conductors are equally objectionable in a large and crowded city, conduit systems have not yet shown their practicability on any scale (though they seem to promise well in this country), neither have storage cars demonstrated their absolute efficiency and economy on the scale desired. There remained the underground tube electric railway, which, without disturbing the street, has been shown by the City and South London line to give a desirable solution of the problem in point of rapidity and safety, as well as facility of obtaining the necessary space for new railway lines without encroaching on the streets. We learn that after considerable discussion, which has been going on for some months, it has just been decided to put down 20 miles of this underground tube electric railway to serve from the business part of New York to the west end suburbs. it is not at all improbable, also, that a similar railway will be undertaken to give communication for the east end district.

CORRESPONDENCE.

"One man's word is no man's word,
Justice needs that both be heard."

BATH.

We believe

SIR,-On January 30 you published among your notes the following:

gratifying improvements have taken place at the Bath central station. The festoons of wire and other temporary arrangements that made this station somewhat like a Yankee station have given place to the neatness and solidity that should distinguish English engineering work. The high-potential terminals also previously a source of our complaints are now covered in with glass and out of harm's way, and matters have smoothed over considerably since the new chief engineer took up his work there"implying that I had left the station in these particulars in a "temporary" and "Yankee "-like condition, which I deny.

"BATH.-We are glad to learn that considerable and

By a remarkable coincidence that number of your paper notice a day or two ago. never reached me, and the above was only brought to my

At the date of your note, and for some time afterwards, the wires were in exactly the same condition as I left them a month before, as were also the switchboards, with their high-tension terminals. Therefore "the considerable and gratifying improvements" mentioned were carried out by me, and not by the new engineer, as stated.

I much regret your inability to give the source from whence you obtained the above information, but trust you will recall these imputations against me by publishing this letter.-Yours, etc. GEORGE S. HOOKER,

late Chief Engineer of the Bath Central Station. 184, Evering-road, Clapton, N.E., July 1, 1891.

COST OF LIGHTING BY GAS AND BY ELECTRICITY.*

BY W. H. PREECE, F.R.S.

I have the pleasure this morning of bringing before you the subject of the relative merit and cost of gas and electricity for lighting purposes, and as a practical man, speaking to practical men, I propose to consider the subject solely from a practical point of view, and to deal rather with the financial aspects of the question than the mere technics. Of course I shall have to deal a good deal with figures, and figures are proverbially dry. It has been said that you cannot extract a joke out of figures, and that you can always manipulate figures to suit your own particular view. Neither statement is quite true, because we have all of us heard the old story about the two men contesting with each other, and one man saying: "Why, sir, it is as plain as two and two make four," and the other man saying, "But two and two don't make four; two and two make 22." And, again, as to manipulating figures to suit one's own purpose, I dare say it will be said I am going to do very much that kind of thing myself. I am addressing you, if I have any prejudice at all, as a gas share holder, and not as an enthusiastic electrician. Comparisons of cost are generally fallacious, because the comparison depends so very much upon the point of view taken. The questions we have to decide are principally such as these: what is the capital involved in any particular industry; what is the profit derived, and what has the consumer to pay? I am not going to bring before you any fanciful figures. They are published figures, and they are figures you can all get for yourselves, and you will be able to check the deductions I am going to make. I have taken the case of Manchester for the simple reason that I have more authentic records of what is done in Manchester than I have of what is done in any other town. And, from the records of the gas department in Manchester, it seems that one ton of coal in Manchester produces 9,611 cubic feet of 20-c.p. gas. I take Manchester also because it is above the average-20-c.p. gas is rather in excess of the average of the country; the average of the country is not more than 15 c.p. Since this is the quantity of gas produced by a ton of coal it follows that Ilb. of coal will produce 4.29 cubic feet of gas, and if 4.29 cubic feet of gas is burnt per hour, we get in Manchester an illumination of 17.2 candles. Now, in drawing a comparison between gas and electricity, I must use one technical term-and I think it probably will be the only technical term I shall use and it is a technical term which is now coming into very general use, and will have to be understood by every engineer, whether electrical or municipal that is, the term watt. A watt is the mechanical unit of power. The common unit of work with which we are most acquainted is the foot-pound, and the unit of power we know best is the horse-power-that is, the power exerted that will raise 33,000lb. one foot per minute. In other words, you may say a horse-power is the power which power which will raise 550lb. one foot per second. The watt is that power which in the metrical system will raise-I forget the exact value in grammes per centimetre, but it is that power which is exerted by a current of one ampere flowing through one ohm for one second. It enables us exactly to tell you how many lamps will be lighted and what light they will give. So in the use of electrical energy, if we burn in a steam boiler 7lb. of coal per hour, we shall produce 1.3 h.p. of electrical energy, or represented in watts we shall produce 1,000 watts, and 1,000 watts is called a kilowatt. So 7lb. of coal will

* Address delivered before the London meeting of the Associa tion of Municipal and County Engineers.

give us a kilowatt-hour of electrical energy, and I will show you what light it will give. In the same way that I have shown that 1lb. of coal distilled into gas will produce 4.29 cubic feet, or 17.2 candles of light, so llb. of coal burnt in a boiler to produce steam will give us electrical energy that will give the following-I will show it in two forms: one the arc lamp, which we use in our streets, and the other the glow lamp, which we use in our houses-1lb. of coal burnt per hour, and used as electrical energy, if burnt in the form of a glow lamp will give 48 candles, and if burnt in the form of an arc will give 288 candles. So here we start with the first theoretical fact that I bring before you, that 1lb. of coal distilled into gas in Manchester gives us a candlepower of 17-2, if converted into electrical energy in the form of a glow lamp 48 candles, and in the form of anarc lamp 288 candles. That is theoretical; we will now come to hard facts. In Manchester, during the 12 months ending March 30th, 1890, the income derived from gas was £434,351, the expenditure was £360,804, showing that in Manchester a balance of £73,547 was derived from gas. That balance was devoted to meeting interest on loans, depreciation on plant, and the cost of public lighting. But from that fact I derive this: that the cost per 1,000 cubic feet of gas to the Corporation of Manchester was 2s., and therefore it costs the Corporation of Manchester 2s. to produce 4,000 candles of light. For the next point I am obliged to use an estimate for the simple reason that at present the Corporation of Manchester have not established a central electric light station. They have obtained a provisional order so as to enable them to do this, and they are now considering whether they shall carry it out themselves or transfer their powers to another body. In making an estimate of the cost of electricity in Manchester, we have to take the experience of the cost of manufacturing electricity elsewhere, and on this point there are at hand more reliable, accurate, and truthful facts than perhaps anything else connected with electricity. The Board of Trade exercise such a powerful control over the electric lighting interest, that there is no "hanky-panky with the accounts. The accounts of expenditure must show the cost of production, and these are within the reach of everyone. My own experience of electricity is a pretty extensive one, for we have a great many of our post offices lighted with the electric light, and I have a central station at the General Post Office, which if you had not your bill full I should have been tempted to invite you to see what we are doing; we have a very large plant and we are going to produce in St. Martin's-le-Grand sufficient power to light 10,000 lamps, besides which we are laying down another plant at Coldbath Fields, where we shall generate electricity for another 10,000 lamps-and from my own experience I can say we can produce a kilowatt, or a Board of Trade unit, for 4d. This means that if we can produce 4,000 candles by gas for 2s., we can produce 4,000 candles by the arc lamp for 8d., and we can produce 4,000 candles by a glow lamp for 4s. So you see, on these facts-I am not calling them estimates, for they are facts-on these facts, the theoretical estimate of light produced is twice as much by the glow lamp as by the gas lamp. However proud we, as gas engineers, may be of producing gas of 20 c.p., when you come to the houses and shops of the users and consumers you find this 20 c.p. is very considerably diminished. This is a very important question, and one which some six or seven years ago concerned us at the Post Office very much, and Mr. Vernon Harcourt, F.R.S., and myself devoted considerable time to experiments on this question. Mr. Vernon Harcourt-who is a very painstaking, careful, and accurate experimenter-found, taking the ordinary burner, supposed to be consuming 5ft. per hour and giving 15 c.p. in London, really gives only 10 c.p., due partly to dirt in the burners, but principally to the flickering of the light of the gas, caused by draughts of air in the room. So, while a light burning in a special burner in a laboratory may give 15 c.p., when you come to a room or passage lamp will only give 10 candles. This pro rata value is equally true of Manchester as of elsewhere. The result is you must add 30 per cent. to the cost of the gas for your 4,000 candles. This is another point. I ought also to say this depreciation in the value of light is

that

So,

very much in London. The private companies are charging 74d., in other instances Sd. In Bradford they commenced by charging 5d., which they have since raised to 6d. In Newcastle they are charging 44d. to the public, and they are allowing a large discount on that price to the large users of electricity. We in the Post Office are large users, and we have a discount of 20 per cent. off that 44d., which makes the cost of our electric lighting in Newcastle very nearly approaching that of gas. In factories where they have isolated installations all facts show that electricity is cheaper than gas. I have figures from Bolton-from Messrs. Horrocks, Crewdson, and Co.-who are very large employers of labour in the district. They have had the electric light going for six years, and while they were using gas the cost per burner per annum came out at 5s. 6d. Since they generated their own electricity it comes out that their lamps cost 4s. 01d., so there is a considerable reduction. Those who know Manchester know that under the Exchange there is a large restaurant, which used to be unbearably hot when lighted with gas. The manager two years ago replaced gas by electricity, and he finds he is not only saving £800 a year in cost of illumination, but has probably doubled his income by allowing his guests to have their meals in comfort. So far as figures go, I have given you hard facts to show there is not much difference between the cost of electricity and that of gas. I tell all my friends that my house is lighted by gas, but I burn my gas in the garden, and allow all the vitiated gases to disappear in the air, while I extract from the gas what I want-light, and have it in the house free from all impurities. If you take 25 cubic feet of gas and burn it direct, you will only have 50 candles of light with a 10-candle burner, whereas if you burn your 25 cubic feet of gas in a gas engine, and convert it into electrical energy, it will give you 160 c.p. in the house. with a little care, you will be able to use the same gas and treble the amount of light in the house. I see in the programme you are going to the Royal Naval Exhibition. The Royal Naval Exhibition is lighted by electricity. There is an engine-room fitted up there with probably the latest developments of electrical machinery, for electrical machinery is constantly changing; we are daily producing improvements of some kind or other. The electrical room is well worth your visiting, and you will see there how the electrical energy is generated, and you will probably find that one dynamo and one engine is supplying the electric current to the whole of the exhibition. On Saturday you are going to have an even more interesting visit to the works of the Electric Supply Corporation, at Deptford. They are not completed, but there you will see preparations that are being made for lighting one million lamps in London. At the present moment there is only sufficient machinery to allow 200,000 lamps. You will be able to see there the space required for electrical machinery to light a million lamps. One of the great merits of electrical machinery over gas machinery is the small space which it Gas requires 100ft. by 50ft. for every million cubic feet per annum; 100ft. by 50ft. is quite sufficient with electricity to light up one of our big towns. We must not neglect other points. We must not neglect the fact that when wedeal with electric lighting we are removing from our midst a source of deterioration to our goods, chattels, and pictures; we are removing something which destroys our decorations, and dirts our ceilings; we are introducing into our houses something which encourages cleanliness; we add materially to our comfort, and by adding to our comfort we add very much to our cheerfulness. I know nothing which adds so much to the cheerfulness of our lives as the electric light. I feel it will even add to our lives. I feel that if I had not had the electric light in my house for the last eight years I should not have been addressing you to day; and I hope when you meet in London 10 years hence I shall be able to come and address a larger body (for you will then be electrical engineers also), and give you experience of the progress and improvements which have been made. Another point is, that it adds so much to the security of our buildings and of our houses. It is not absolutely safe; it would be absurd to say it was. Carelessness and folly will cause fire by electric current as by gas. It requires

not only true in the case of gas, but also true to a certain extent in the case of electricity. The lamps when they are still fresh and new give 16-c.p. light, but after they have been used 200 or 300 hours there is a peculiar effect of the electricity flowing through the carbon filament that causes the carbon to evaporate-it flies away in straight lines and is deposited on the glass bulb, obstructing a certain amount of light. Again, you have a Again, you have a certain amount of dirt and dust collected on the outside. The consequence is you have a depreciation in the amount of your electric light, though not quite so much as in the case of gas. I ought to mention, without drawing any distinction between the light-giving power-whether electricity or gas-in the light given by each, that five cubic feet of gas will give practically 10 c.p., and 33 watts in the normal power will give you also 10 c.p. There is one element of loss in gas that is very serious indeed that is, the tremendous waste of gas that occurs through lights being left burning unnecessarily. Persons who have their houses and offices lighted with gas know that servants, as a rule, go and light all the burners, unless a careful householder goes round and cuts off those that are not wanted. The result is this: from this very element of waste there is 20 per cent. of gas used more than is necessary. This fact is brought out thus: taking the nine principal towns in this country, and taking the average numbers of hours of gas and electricity burnt in this country, the average number of hours for gas is 600, while the average number of hours for electricity is 460. The figure 460 is taken from the average of 200,000 electric lamps which are now alight in London. While in gas you have a tremendous waste from these burners being left flaring, you have no waste from electricity. Electricity is so easily lighted-a tap turns it on and off-that there is a species of instinct that teaches everyone that you only want your electricity alight in the place where you are using it, and at the moment you are using it, and the result is you get no waste. The result of it all comes to this: that the comparison between gas and the glow lamp is not 2s. as against 4s., which is theoretical, but the practical figure of 3s. 8d. against 4s. We can prove this. The average amount, taking the returns from the chief nine towns of this country, paid per gas burner per annum is 9s.; the average price of gas being 3s. per 1,000ft. The average price of the 200,000 electric lamps burning in London is 10s. So we have these two facts. That the average price paid per burner by the consumer for gas is 9s. per annum, the average price paid by the consumer to the electric light provider is 10s. This is a rather startling figure, because most people are under the impression that the cost of the electric lamp is very much greater than that of gas, and I have been myself very much surprised that the price I pay in my own house, where I generate my own electricity and have done so for the last eight years, was so very small. I find, although I have a gas engine and accumulators and have over 70 lamps, I am not paying more than when I had gas burners. I have taken all the companies in London, and have tabulated the revenue derived by each company per lamp per annum, taking the 33 watt lamp and the 10 candle burner. The Metro politan Electric Supply Company derive a revenue of 12s. per lamp; the Chelsea Electric Supply Company, 8s. 6d. per annum; the Kensington and Knightsbridge, 9s. 2d.; the House-to-House Electric Supply Company, ils. 6d. per annum; the St. James's and Pall Mall Electric Supply Company, 9s. 6d. ; and a company, not in London, but in Brighton, obtains 8s. 6d.-the mean for 200,000 lamps being 10s. I have also verified myself this ratio between the two. In the General Post Office, where we burn a great quantity of gas, and where night operations are extended to late hours, and begin at early hours in the morning, there, from the experience of two years' working and comparison, we find that gas costs 18s. per lamp, and electricity 22s., so the ratio there is one of 9 to 11, and not of 9 to 10. Take the case of Manchester, where gas is cheaper than in other towns. The average price paid per lamp for gas in Manchester is 7s. 6d. per annum, while taking the cost of electricity to the consumer at 5d., the revenue that Manchester will derive from electric 'amps will be 8s. 4d. Of course the rates of charges vary

uses.