reasonable cost. The amount of energy available is dependent upon local conditions peculiar to each road.

Most of the car heaters now used are air heaters; that is, the resistance is so arranged as to permit the air to impinge directly against it and carry away the heat by convection currents. The heat ascends to the monitor and is rapidly diffused with the cold air sifting in through openings in ventilators and window frames.

It may well be questioned in the light of modern heating practice whether this form of heater is best adapted for the peculiar conditions in car heating work, which really should be not heating at all, but effective warming. In common house heating, where electric heaters are used to give results immediately, they are connected in circuit; this is a better way to make the heater than a radiating surface. But in car work, where the heater is practically continuously in circuit, the radiator forms a better means of keeping a large percentage of the heat delivered at or near the floor of the car and about the bodies of the passengers.

The car heating tests made show that with the use of about four horse power the interior of the car can be kept practically at 50 degrees F. From one point of view this is too low a temperature for comfortable passage. And yet if the heater is devised to deliver a part of its energy to the floor of the car, to keep it warm and dry, and about the limbs of the passengers, this is high enough for practical purposes. The problem of car heating practically resolves itself into providing a form of foot warmer heated by electricity and used for effective warming rather than for heating per se.

On the Esquimaux plan of huddling together for warmth, a car can be kept at about 40 degrees F. by animal heat; each adult passenger gives off 190 heat units per hour, or 14 passengers will give off as much heat as one electrical horse power hour. There are cases in practice in which the animal heat on some runs is practically the equivalent of the electrical energy used in heating. Clearly, then, the proper use of electrical energy is on the basis of individual effectiveness rather than for heating as commonly understood.

Using the methods commonly employed for computing the heat necessary for warming, a 20 foot car requires eight horse power hours to keep it at 65 degrees with the outside air at zero. In the cars examined in use the energy supplied for heating by e'ectricity was about equal to the loss from glass radiation. There are cases in which the energy used for heating by electricity is 40 per cent of the energy used in operating a particular car. And

yet, assuming that five horse power is a fair average for use, the cost is about $10 per month per car for heating, or about 33 cents per day or two cents per hour. The use of five horse power is a high one for effective warming, as it would heat 37 square feet of radiating surface to 185 degrees with the car at 50 degrees, while with the best systems of radiation for complete diffusion yet suggested the surface available is about 30 square feet, requiring four horse power to heat.

While most of the electric car heaters now supplied do not meet the conditions here imposed the fact that several thousand cars are equipped with and are using the heaters attests their value. I beg to quote in this connection from a letter written me by a well known street railway expert:

"I think that the decision for or against heating in any particular case will have to be given with the distinct understanding that collateral advantages and not coal economy form the real criterion. You will remember that I spoke to yiu about a large plant which had been using heaters this winter with a very great expenditure of power. I had a talk with the manager a few days ago with the following results. He admitted immediately that it is costing him considerbly more, in fact, about four times as much, to heat his crs by electric heaters as it did by coal stoves. He says, however, that he saves two seats in the car, that the people like the system of heating, and the cars are more attractive for this reason, and that on the whole he believes in it and would not go back to the old system, nor would he fail to adopt electric heating if the decision were to be made again."

This expression of opinion has been selected, notwithstanding the unfavorable comparative cost statement, to illustrate how far we have to be governed by cillateral advantages in deciding for or against any particular application of electricity for heating purposes.

More large contracts for electric car heaters have been closed the past season than ever before, and there is every evidence that the electric car heater has become a staple commercial device. It would seem in view of the facts, that the statements contained in Vol. I of the transactions of this society regarding electric car heaters should not stand without correction. The Metropolitan West Side Elevated Railroad of Chicago are now heating by electricity 155 cars, each 38 feet 8 inches long; 7 feet 10 inches. wide; center height, 8 feet 63 inches; side height, 6 feet 7 inches. Glass surface is 208 square feet. There are 12 heaters to each car, using maximum of 7,000 watts. The energy used is divided

into two parts of 2,600 watts each and one part of 1,800 watts. The practicability of the equipment is shown by a recent order for 25 more equipments.

II. Air Heaters.-Outside of car heating these heaters have been used to a wide extent. One of the largest installations is in the office building of the Cataract Construction Co., at Niagara Falls, where all the heat is derived from this source. In cabins of steamships and yachts, bath-rooms of houses, offices, libraries, etc., they are found useful devices. The writer pointed out in "Heating and Ventilation" for December, 1895, the relation which these heaters bear to steam heating systems.

In England and France installations have been made on a considerable scale, and the work is of course simpler than the problem confronting us in this latitule, where the maximum capacity requires to be nearly twice the average. In heating the Vaudeville Theater in London, the engineers write that they had to compete against a low pressure hot water system. There was difficulty in finding a suitable place for the furnace on that system, and in using electricity this difficulty was overcome. It is found in ordinary cold weather that only two or three hours' heating are required, but with hot water systems it is impossible to limit the time in this manner, as the water takes two or three hours to heat up and the same time to cool down. The charge for current is 4d. per unit (about 6 cents per horse power hour). The lessees of the theater have expressed themselves perfectly satisfied with the results.

In this work the fact that heat is used only intermittently produces economical results, with even very high current rates. Take the case of a bath-room: capacity of heater, one horse power; duration of use per day, 20 minutes; rate for power, 10 cents per horse power hour; cost per day 3 cents, or practically $1 per month.

III. Electric Cooking.-The results obtained in this line have. been in a number of detached installations. Enough has been accomplished to show that electric cooking apparatus is practicable to use, economical in running cost, and extremely simple to operate.

Theoretically, of course, the oven is the device of highest efficiency and it is also found in practice a device of the greatest practical value. In Science for September 15, 1893, will be found the most comprehensive data regarding the comparative cost of operating the electric oven and the common cool range yet published. It is shown that the cost at average rates for electricity is

practically the same for the coal range and electricity, provided an auxiliary water heater is used with the electric oven. It is not always possible in practice to confine the electrically heated apparatus to types as economical as the oven; but in a plant operated for several months and in which ordinary types of cooking utensils were used, the cost was found to be 2.5 cents per person per meal. Separating the energy used in this latter case for cooking from that employed for water heating and the cost would be reduced by about one-third, or to 1.7 cents per person. Even at the 2.5 cent rate the cost (including time and attendance) compares favorably with other sources of heat for cooking.

IV. Industrial Applications.-In factory work all the elements for a multipotential heat supply are usually present and the field for electrically heated devices extensive. Three examples have been selected as illustrating this class of work.

A. Equipment of a brush factory. In this instance pitch is used. to fasten bristles in the brushes and is kept above 300 degrees F. in jacketed electrically heated pans. In addition, hot plates and glue pots are used, all heated by electricity. Current is derived from a dynamo driven by a gasoline engine. For a run of ten hours the cost of heating each pitch pan is about 4.5 cents, which is considerably less than was the cost of running by gas.

Commenting on his plant the owner writes:

"When we built our factory we had confronting us the problem of obtaining high temperatures for heating pitch and other applications without employing gas or other forms of flames or fire in the shop which were objectionable from the underwriters' standpoint and which we have solved by the adoption of electricity for these purposes."

B. Sad-irons in a linen factory. This installation consists of 125 9-pound irons heated to about 750 degrees surface temperature. For this plant additional dynamos were bought, and its success is evidenced by the fact that it is shortly intended to double the equipment. Each iron uses 550 watts or about horse power per hour as a maximum.

C. Glue pots in book binderies.-Two installations of 25 pots each. These show the value of electric heating in the subdivision of heat energy. The pots are provided with water bath, and the energy supply so adjusted to compensate for heat loss without material evaporation. The energy used by each pot is from 150 to

200 watts.

These may be regarded as typical illustrations and indicate roughly the adaptability of electric heating in industrial work.

Where electricity is used in place of flame or fire the ventilating problem becomes much simpler, and this is of great importance in crowded work-rooms.

It is not too much to claim that electric heating will materially influence the work of heating and ventilating engineers. Now that electric lighting installations are handled by heating and ventilating engineers it is a short step to render the entire heating system homogeneous, looking to one source-the boiler-for all the energy needed for heating, lighting, and ventilating. It is possible to economically regulate and provide storage capacity for both the high and low temperature factors; the plant becomes compact, self-contained, and simple and economical in units of moderate size. The system is elastic to the highest degree.

DISCUSSION.

Mr. John Gormly:-I would like to ask Mr. Hadaway if he has any data in reference to the weight that is required to be carried in a car radiator. That is, for the heating of a car so much dead weight has to be carried; has he any data to give us on that subject?

Mr. Hadaway:-In the experiments made the weight of the radiating surface has varied from 125 pounds as a minimum to 210 pounds as a maximum.

Mr. Stewart A. Jellett, (Vice-President Mackay in the chair):— Gentlemen, I am not posted on electric heating, but there are one or two things brought out in this paper that interest me very much, and I would like to say a few words about them in order to get further information. What has impressed me all through has been that there is no particular difficulty in electric heating, that is, with the generation and transmission of the electric heat, but that the one thing which stands in the way of its introduction is the cost. It is a comparative question throughout. Therefore I would like to ask for information as to what is now under consideration by electrical engineers throughout the country towards the reduction of cost of generation of electric current, and second, with respect to the transmission of the current. I was talking to a gentleman a short time ago who was very much interested in this matter, and he told me that he was at work with some others on a new problem of generating gas from fuel and passing it directly from the furnace to the engine without the use of a boiler, and in that way he hoped to very largely reduce the cost of generation of the electric current; that the experiments so far conducted had been of such a nature as to lead them to hope for ultimate success; that ten of