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tains that characteristic, and as soon as it begins to be over-loaded it drops off-that effect I mentioned, of drag increasing more rapidly than the torque. The meter which I spoke of in my paper which had folding fans, started in something like this, (curve 2) I am speaking of individual meters which I have tested. I think I can explain this. That curve is greatly exaggerated. That low start is friction again. The curve goes up here. That is all right. Perhaps our zero line ought to be there. In reality the meter may have been calibrated too high. Here the fans begin to shut up by the device which closes them like a steam engine governor. That causes the retarding effect the dragto increase much less rapidly, and the meter speeded up again. This fall here was caused before the fans began to be moved by centrifugal force. Here the fans got closed up entirely, and the resistance increased more rapidly than the torque.

Taking out these lines, I will draw a characteristic curve, as I have found it with a great many tests of Thomson meters of average size. (Curve 3.) This is our zero line again. The law of the meter is correct, the only error which we find being on the lower reading where possible friction is not properly compensated for. I have tested meter after meter which did not show that dropping curve even on one lamp. I might go into an endless number of curves of various meters, but I do not think it is called for. I do not know that I need to comment on the meter described just now. It has found its parallel in two or three other meters, and after all, it is not so much unlike the meter I described as having a rotating basin of mercury. It might be described as a form of the disk meter with modifications.

As to the question of the watt-hour, whether the watt-hour is the proper basis to charge by: first, I think we ought to consider that the watt-hour is a universal basis. A watt-hour means just the same thing whether a man is using 500 volts, or 50 volts, or 10 volts, or 1.000 volts. It is a watt-hour, and has a meaning, no matter what the voltage is. That enables us to have uniformity of rates and uniformity of constants, and to do away with the confusion that results from a number of constants. Again, it is undoubtedly the unit of power, and it seems to me that what the station man wants to measure, is what he is putting into the lamps. I think that measurement by ampere-hours, which by the way, is generally warped by the customer into the term "lamp-hour' (which is very deceptive), is much as if we had started by charg ing for gas by the burner-hour, irrespective of what is burned. Now, it is very common in some places for the consumer to furnish his own lamps-very common indeed-especially among small stations, and if the consumer furnishes his own lamps, perhaps he furnishes a lamp that takes 70 or 80 watts: then he will, as a rule, object to his bill very strongly, because he counts his lamps and he counts his hours, and his meter does not agree and does not tell him the some story. The same, again, with fluctuations of the

pressure the old story that the "lamp-hour" meter is not what is wanted, because every fluctuation of pressure introduces an opportunity for a quarrel between the consumer and the station man. I think I might enlarge on this much more fully, if I dared to take more time.

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A very important question was touched on here to-night, and that is the energy that is expended in the meter. I think the statement which was made is misleading. Surely, what the station superintendent or the station manager wants to know is, "how much more will it cost me to operate my system with a meter using a certain fraction of an ampere all the time, than it does to operate my system without that meter?" Well, to generate that amount more current, it is not likely that he would have to put in any more dynamos, or any more engines, or add to his battery of boilers. He would probably not employ any more linemen, or any more station men, or any more wire men. would burn a little more coal. He would probably evaporate a little more water. He might possibly use a little more oil. In other words, it is the difference between the cost of running the station without, and running the station with, meters that he must consider; he must not say, "Here are so many amperes that my meters 'consume,' and I get a cent an ampere-hour, and my meters are costing me four million dollars a minute." I think that if the drop on the line, or any of the many losses the station man has to meet, were considered on the basis of what he could sell that amount of current for, he would soon find the debit side of his books discouraging.

I do not think that I need reply specifically to the difficulties. which a gentleman presented relative to the use of the wattmeter on an electric crane, the crane being remote from the station, and there consequently being a considerable drop on the line. I do not quite see how this bears upon the meter question at all. Yet it seems to me that it simply means that a good deal of energy was being wasted in getting the power to the motor, and I think heavy wire would be the remedy for that. Certainly what the consumer wants to pay for is the service of the motor, not the maintenance of the system.

I was asked, I think, what could be considered an admissible percentage of error for a meter on an average load. That is a very nice question, because no error is really permissible; but I think it has been generally accepted by almost everyone, that an average error not to exceed three per cent. is not to be grumbled at, in the present state of the art, and there is more than one meter existing to day which will do better than that on average loads, and even on light loads.

Referring to such meters as mark a curved line of fluctuations in current or pressure, or anything else on paper, the device of a sparking coil connected to the indicator point and puncturing or marking the paper was mentioned. I might say that I did not

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mention that in my paper because I did not think it really important enough. I have seen such instruments and have experimented with them. The only objection seems to be that the spark is erratic. It does not go straight through the paper. have seen it vary from one-sixteenth, to one-eighth of an inch from the right direction, and it will not always puncture the paper directly under the pointer. That is the only objection I know of to that. Of course, in using such a device it is best to use a paper which has been so treated that it will be discolored by the spark.

The Board of Trade question perhaps needs a little further consideration. The Board of Trade was evidently satisfied with instruments which certainly showed considerable error, but if my memory serves me, the Board of Trade insisted more on certain details of mechanical construction. Of course they insisted on certain accuracy, but they were more inclined to dictate as to the character of the mechanical construction, the facilities for installing and similar details, than they were as to what was really the essential thing, what the meter should record, what it should do. It was a great surprise, I think, to more than one meter man in this country that they should do so. Methods of sealing were given great importance.

A meter was mentioned just now as having been shown at the Paris exposition, which embodied, it was said, the qualities which I mentioned as probably the best to apply in an ideal meter. I notice in the description of this meter, which, by the way, I think I know, that electro-magnets were used for the damping mechanism. Whilst it is undoubtedly very good practice to use them, they are probably not the best thing to use. In the first place, electro-magnets, unless they are separately excited, are scarcely fit for alternating work, and, again, they expend energy in the meter, and, again, they are apt to vary somewhat in saturation, with fluctuations of potential in the line. A properly constructed permanent magnet is, I believe, preferable for this work. I think I have replied more or less definitely to everything that was suggested in the discussion. I thank the members for their kind attention.

THE CHAIRMAN:-The Chair has been much interested to note that the habits which any form of apparatus acquires as a genus, when there is but one species, is usually perpetuated when the species is increased, and from casual remarks whick Mr. Haskins and the other speakers have dropped, it is evident that the bad habits ascribed by consumers to the gas-meter are perpetuated in the electric-meter. It is perhaps satisfactory to those who are not consumers to know that.

I would wish also to call attention to one feature of the paper which has not been commented on by any gentleman, and that is the remarkable performance of the Aron meter, as noted on page 40. If any one of us possessed a meter which produced for its

owner five thousand francs, and half a gold medal, I think you would all agree with me, that that person had become possessed of the goose which laid the golden egg. Meters do not ordinarily do that for their inventors.

I am sure that the Institute will join with me very heartily when I propose a cordial vote of thanks to Mr. Haskins for his paper, and I will ask all who agree in that motion to say "Aye." [The vote was carried, and the meeting adjourned.]

[COMMUNICATED, AFTER ADJOURNMENT, BY MR. TISCHENDOERFER.]

Mr. Haskins is right in saying that the damping effect of a shunted electro-magnet depends on the line potential. This variation of the damping effect can be made very small, if the electromagnet is practically saturated for the lowest working potential, so that the increase of M. M. F. of the electro-magnet, due to the increased potential, increases the magnetism, and consequently the damping effect, to a very small extent only. This increase of the damping effect, however, is counteracted by the increase of motor torque, due to increased strength of the shunt field.

AMERICAN INSTITUTE OF ELECTRICAL

ENGINEERS.

New York, February 21st, 1893. The seventy-fourth meeting of the Institute was held this date at 12 West 31st Street, and was called to order at 8.30 P. M. by Vice-President Lockwood.

The Secretary announced that at the meeting in the afternoon the Council had officially adopted the design for a badge submitted by the Committee which had been appointed for preparing designs for both badge and certificate. Arrangements had been made for the manufacture of the badges from 14 carat gold, and they could be furnished to the membership at $3.00 each, provided a sufficient quantity are ordered. Members desiring to purchase should order them at their earliest convenience. The following Associate Members were elected:

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