Discussion. The Chairman :—Gentlemen, it is impossible that one of your number c<m sit in this chair and preside over your sessions at intervals for more than a year, without noticing the demeanor of the several listeners to a paper like this, and forming, in some sense, a conclusion as to the degree of interest which it excites in the minds of the member?. I have learned to observe the faces and the habits of the several members, and I have learned to consider it an excellent sign when several members who are reading the paper and following the speaker, turn over the leaves a brief instant of time before the reader of the paper turns over. This has been uniformly the case this evening, and I observed this evening that about three words before the speaker reached the end of the page, the listeners were ready for him, and would turn over the pages. I will not undertake to indicate the trend that discussion should take at all. I think the members who have heard this paper read are well able to appreciate its value; but the Chair does desire to say that he believes that, when incorporated in our proceedings, it will form a valuable addition to our Transactions and will be well worthy of re-reading over and over again, as we shall reach it, not only as we receive the proceedings by mail in the separate numbers, but after they are bound. I notice with {>leasure the brief intimation at the head of page 28, where Mr. laskins speaks of the inspector of meters measuring the thread on his yard-stick and finding out how many yards of electricity the consumer had used since the inspector last visited his place, and, although perhaps a little out of order, I may say that it reminded me of an incident which occurred,not in my own history, but in that of my father, who lived, as I did in my youth, near the Soho Foundry, where Boulton and Watt made their first steam engines. Murdoch, as most of yon know, worked there and was one of the earliest, if not the earliest to strongly advocate the general introduction of coal gas as a means of illumination. It took him some time to find that his views were feasible. It took some time before coal gas became recognized as a valuable means of illumination. But Murdoch was early impressed with a strong sense of its value. He told to my father an anecdote concerning its introduction, to the effect that after they began to manufacture coal gas at the Soho Foundry, very frequently farmers would come with sacks on their shoulders, for a sackful of it, and would go away greatly disappointed on finding that they could not carry it away in sacks. There is perhaps more sense in measuring electricity by the yard, and I am glad to see that we have got down to such a practical method of measurement. This paper deserves full and free discussion and I trust it will get it, because that is the greatest compliment that can be paid to any person who prepares a paper and comes to read it to us. Mr. Townsend Wolcott :—Mr. Haskins speaks of a thermometer. I would say that thermic meter would be more in accordance with the rules of the English language. It is hardly fair to lay the blame of a word having two meanings to the English language. Thermic meter would indicate one in which heat played some part, but not one which measured heat. Mb. Haskins :—I am very glad to be corrected in that matter, I am sure. I used the word thermo-meter because it appeared in Patent Office literature. It is a term commonly used to designate this class of meter. Me. Wolcott :—Yes, sir ; but the language of patents is generally a very poor place to go for English. Again, on page 45, Mr. Haskins says:—"This meter is, of course, equally useful without change of calibration, on either a direct or an alternating current of any frequency." I have understood that the meter was correct on alternating currents; but the reason I mention this is, that the "of course" is not so plain to me, why the meter having the fine wire armature in the shunt should be accurate with the same constancy of calibration, with alternations of all frequencies. Unless the inductance of the armature is a negligible quantity, it would seem to me that there should be corrections for each change in frequency. One other point. The Thomson meter seems to be a very accurate and beautiful instrument. There is only one fault I can find with it. There is a series of pointers passing around by a continuous motion, and if you look at the meter frequently, there is never any trouble about it. But sometimes you read a hundred or a thousand wrong. When the hand gets on the other side of the graduation, you are not sure which side of the graduation it is on. There is a device for overcoming that, by using a hand that moves all at once. Sometimes we use what is known as the Geneva-stop movement in watches, but that introduces a friction. It seems to me that by running a little extra energy from the main current, that friction could be overcome at the point where it interferes with the meter. Peof. E. O. Heineich :—Having heard from Mr. Haskins about the general lines on which the inventive genius has been at work in this very serious meter question, we would all I am sure, be thankful to the gentleman if he would give us from his large experience some information on the general behavior of those meters which came under his observation. There is very little literature on this subject, beyond the mere description of meters usually in connection with the indefinite statement that the apparatus is extremely accurate. 1 beg to anticipate such information in giving some details on the Teague meter, of English make which was shown to me as one of the very few which were approved by the Board of Trade. From this statement we must assume that the London Board of Trade is satisfied with an accuracy as shown by this meter. This Teague meter is a motor meter, in principle and construction exceedingly simple and certainly very commendable as far as that is concerned. It is very compact, up to a capacity of 50 amperes, it is 6£ inches in height, 4f inches wide and 6£ inches deep at its base. In the cross-section shown in Fig. 2, i represents a cast-iron cylindrical shell, with the cast-iron parts i, and i2 screwed in at top and bottom. The latter two form the two concentric poles of an electro-magnet which is excited by the field winding w. A very intense field is thus formed in the circular space between i! and i2. The armature consists of a copper Fig. 2.—Cross-Section of Teague Meter. I. Cast-iron shell, with pole pieces i and 12. A. Armature consis'ing of a nickel plated copper cylinder. cylinder closed at the top and pivoted in a hole drilled into the central iron core i:. This copper cylinder is thus free to rotate about its central axis, this rotation being communicated to a registering device in the usual way. The lower part of the interior at s s is filled with an insulating materia], so as to form a circuit through M M partially filled with mercury. Mercury connection is likewise made at the point where the armature is pivoted. The main current passes into the lower mercury through M M, thence through the copper cylinder to M, where the metal of the electro-magnet forms the other connection with the main circuit. The field winding w w is connected in shunt to the main circuit. Those parts of the armature which are immersed in the mercury are nickel plated, which is claimed to be preferable to amalgamated contacts. In a similar meter shown to me at the same time by the inventor, Professor Perry, the concentric poles of the electro-magnet had a fluted surface so that the toothlike projections of the external pole were placed opposite to similar projections of the internal pole. [See Fig. 3.] The armature would thus rotate in magnetic field of varying intensity, the induced currents generated during rotation in the armature increasing the "drag" which is a very desirable feature, as Mr. Haskins has pointed out. Professor Perry also proposes to immerse his armature almost entirely in mercury, so that the surface tension and friction connected therewith, will only exist where the shaft of the arma Fig. 8.—Perry's Meter. Horizontal cross-section of field magnets. ture emerges from the mercury. (Mercury to be used for the purpose of making contact for large currents does not seem to me to be a desirable and practical feature of a meter under any circumstances.) Returning to the Teague meter, I was informed by the maker, that its greatest number of revolutions does not exceed 25 per minute, which would be a very good feature of this meter. The speed curve given to me and represented in the diagram, Fig. 4, represents most likely the meter at its best, otherwise it would not have been made public. This curve is taken from a meter which is to register from half an ampere up to 25 amperes. The following table is compiled from the speed curve, in which the heavy line indicates rising, the dotted line falling current. The readings were taken at a temperature in the case of 25.5 C. Mean of total number of observations 2.755 Watt-hours per turn. This meter shows bad frictional errors for tlie lower ranges, and is not reliable below three amperes, that is below 12 per cent, of its maximum capacity. Taking the useful range, from 3 to 25 amperes, this meter is right within about 2 per cent., the error being in this case mostly in favor of the consumer apparently, although the percentage error for risiug and falling current would to some extent have an equalizing effect. It would however, be only a question of time and of a very short time at that, when the error would be entirely against the consumer, since the frictional errors in this type of meter must increase very rapidly. It is quite a different thing to criticize an instrument from a laboratory test, and from tests made in actual practice extending over a longer period. The Board of Trade of London seems then to be satisfied with an accuracy as exhibited by this meter; I do not think we would be satisfied with it in this country. Mr. Haskins mentions in his paper, "that the watt is the only true unit for the measurement of electricity by meter." In principle I agree in this completely with Mr. Haskins, but the general public seems to think otherwise. This very day I was informed by a gentleman from one of the Edison illuminating |