well ventilated and quite rapid, the temperature would be nearly the same if ventilated near the floor line.

XXII. TOPIC NO. 10.

What number of cubic feet of air per minute can be warmed to a temperature of 160 degrees by a square foot of heating surface in a heating drum?

Mr. Hoffman:-I think that largely depends upon the size of the furnace.

XXII.-TOPIC No. II.

In a fan system of warming is there any reliable rule for figuring loss in transmission through horizontal ducts?

No discussion.

XXII.-TOPIC No. 12.

What is the best method of equalizing a gravity system when steam is generated in two or more boilers?

No discussion.

XXII.-TOPIC No. 13.

Should not house heating boilers be rated on the number of square feet of grate and heating surface rather than by naming the amount of radiating surface they will carry?

Mr. Fish: Our catalogue gives all that information. (Laughter). I am not ashamed to put down the square feet of boiler surface and grate surface and let the engineer figure it out for himself, and, if it is too high, cut it down. In a revised edition of our catalogue I have put down the square feet of actual boiler surface in our work, together with the square feet of grate surface and the approximate horse power, so that he who runs may read, I suppose, and figure accordingly.

XXII. TOPIC No. 14.

Is the use of the steam loop for returning condensation from heating surfaces located below the water line of boilers of value, and can its field of usefulness be extended?

Mr. Cary:-I do not know how easily I can answer this question. I have used the steam loop and it has worked very successfully. Others have put it in and it has been a flat failure. Where it has failed I have not followed up the method or design.

That may be

the trouble, but I do not think so. I think there is a great deal in

the man in charge of the plant. To illustrate: In one plant I placed a steam loop; I had a good engineer and it was very successful. I severed my connection with that concern some one or two years afterwards and the engineer has left them. They have had two engineers since and neither one could make the steam loop work. I think it has to be looked after like everything else and if properly cared for and properly installed I think it is a very serviceable thing, and it is one that I would advocate if I thought it was going into proper hands to be properly taken care of and operated.

Mr. Payne: I have had quite a little experience in connection with installing steam loops and kindred systems, and I have found that the claim made by the men who were the first to push forward the steam loop is quite true, which is, that the simple, steam loop is not adapted for a system but can be handled on one apparatus or possibly two successfully. Then, in following up that idea, Brown & Sharp, of Providence, wished at one time to install a steam loop and they called upon the Westinghouse people in regard to the matter and they refused to put on a single loop to take care of the system. Mr. E. P. Holly, who was then with the Brown & Sharp people, conceived the idea of putting a receiver on the end of the loop and connecting the system to the receiver. He put this in and made a new form of standpipe. Instead of using the regular leg and horizontal condenser with a drop leg, he put up a piece of 6-inch pipe and connected the rising leg to that, making a reservoir at the top and taking a return pipe to the boiler from this reservoir and carrying a pipe from the top of the length of 6-inch pipe to a condensing coil, which is used for the purpose of having the steam flow to supply the condensation in the coil and so carry the water to this point.

There is a system in Pawtucket, R. I., which is taken care of by the steam loop. But to do this they have had to put in eight or nine loops. When we take into consideration the condesation in all of the various condensing portions of these loops I think we have got a pretty extravagant apparatus. All this takes a considerable amount of steam and the question in my mind as to the advisability of using the loop in that manner is whether it would not be more economical to use a pump. Mr. E. P. Holly, in following out the idea before referred to, has developed it a little further and instead of using the condensing coil he places a reducing valve on the top of the 6-inch standpipe, carrying the steam from this reducing pressure valve over to a feed water heater or somewhere else, or, as it has been installed in this city, he throws it out of doors. Under certain conditions I believe this is a very extravagant method also.

I have seen it in operation where the amount of steam wasted was fully sufficient to run a pump doing the same amount of work. Should the system become flooded, instead of the water returning to the boiler, it will very frequently blow out through the reducing pressure valve.

There is still another system which has been developed and which has been put through the patent office by a man named George Parker and I think his idea of the matter will prove much more successful than either of the two former. I have seen it in operation, and whereas in the other two systems they provide a blow-off valve for blowing out the system as soon as it becomes flooded, I have seen the blow-off pipe in the Parker system put on, but capped on the end so that it is impossible to use it, and it was only last week I was looking at a system where it never yet has been blown off since the first time it was started. If it becomes flooded it starts itself. You still have a waste of steam which of course is absolutely necessary. You must have some energy to do the work. But the waste is very much less than in the other two methods. But Mr. Parker is not pushing his system at present because he has not experimented with it and cannot say exactly what it will do. The Holly Steam Engineering Company are putting in their system, but if they put it in in connection with a condensing coil they have not yet got to the point where they can say how much of a condenser is necessary to do a particular amount of work. I have known several jobs they have put in, starting with a given amount of condensing coil and keeping increasing or decreasing it as the cases might warrant until they happen to strike the right amount.

In regard to the statement just made that the cause of a steam loop not operating would possibly be the fault of the engineer, there is another condition, I think, which must be considered. If you make a pocket in your pipe, or if the pipe should sag and form a pocket in it and collect water, and suddenly throw it and cause a flooding, it would stop. In a great number of instances where the system has failed to operate, if it is looked into, you will find considerable trouble in the piping. In Baltimore there was a system erected for the General Electric people and when it was first started it operated satisfactorily. Then it suddenly stopped, and the sudden flow of water to the cylinders very nearly caused a serious accident. We sent a man down there to look over the job, and he found that there were slip joints put on. I think it was either a 1 inch or a 2-inch pipe and it had not been properly supported; the piping had sagged and caused a pocket and that had collected water, which, when driven over,

flooded the system, which of course stopped the whole affair. He took this out and put in a piece of bent pipe about twelve feet long which provided for expansion and did not form a pocket. I think this is a very wide subject, and it is very possible that the system will be used in the future with good results; but it requires a large amount of experimental work to determine the exact value and the exact proportion of the various apparatus.

Mr. Barron:-I think I suggested the question. I had occasion lately to take the drip from a large pipe below the water line, lowpressure, working at ten pounds pressure, and I had to decide whether I should use the steam loop or an automatic trap, and I decided to use the automatic trap for the reasons Mr. Cary gave.

XXI.-TOPIC No. 15.

What quantity of water should sectional house heating steam boilers contain in proportion to their grate and fire surface?

McClellan Davidson:-In considering this subject the first step to be taken will be to consider the grate surface and its relation to the heating surface, or absorbing surface, as you please. In boilers of the present day the absorbing ratio is anywhere from 15 to 60 to I of grate, the first instance representing a loss of fuel, the second instance a saving, or at least intended to be. But if placed indiscreetly, allowing opportunity for soot to accumulate upon these surfaces, they naturally become ineffectual for heating, aside from the fact of offering obstruction to the products of combustion, impairing the efficiency by sluggish draft. In view of the aforesaid it would be necessary to take some standard in order to arrive at a proper solution of the question. A boiler absorbing only 800 units is not as effectual as one in which the absorbing surfaces will utilize 1,000 heat units per pound of coal consumed. Therefore, in the first instance, one-fourth less water would meet the demand. One square foot of grate surface will consume from five to ten pounds of coal per hour in a good boiler. Eighty thousand B. T. U. can be made available in reconverting the entailed water into steam with a consumption of eight pounds of coal, or the complete evaporation of eighty pounds of water per hour, assuming the return water to be at or about 200 degrees. If the radiation attached to the boiler demands this amount of steam, it naturally follows that, the demand and supply being equal, you cannot have a reserve. Hence, the necessity of supplying an additional amount as a factor of safety in overcoming rapid firing, filling of mains and radiators with steam, low water, a possible false line, etc., all of which should be taken from the boiler without lowering the water line to a point of

danger. This factor of safety I consider equal to one-half the demand made upon the boiler, which is 80 pounds plus 40 or 120 pounds per square foot of grate. If we get too small a quantity of water, requiring excessive boiling to meet the demand upon the boiler, it becomes an objectionable as well as dangerous feature, foaming being a direct result of rapid firing or insufficient water. In other words, it is a result of overheating the water. When surfaces become heated to a high degree the water is repelled, as it were, caused by the formation and explosion of steam particles at the base of the water column, which is the fire surface of the boiler. Too much water carries with it a train of objections also, such as length of time necessary to get up steam, being sluggish in circulation and offering opportunities of deposit, and the impossibility of obtaining dry steam. I have never been able to obtain any literature bearing directly upon this subject. Writers who give steam heating and boiler construction any consideration say that boilers should contain water to fill all mains, risers, radiators, etc., with steam, without lowering water line to such an extent as to require attention. It strikes me that this is a subject which calls forth our engineering talent, and I, for one, would appreciate the opinions of this society upon the subject.

Mr. William Kent:—I have not had much practice with sectional house heating steam boilers, but from what little I do know I do not think that they differ materially from boilers used to drive steam engines. The question what amount of water should be contained in a steam boiler generally is one that has been answered all the way from no water at all up to an enormous amount. Boilers have been driven, I understand, with no more water in them than merely a jet sufficient to keep the plate wet. If you have a series or sectional boiler and can manage to keep the tube wet you can run the boiler with no more water than that. In fire engines-engines for putting out fires-the object is to have as little water as possible in the boiler in order to get up steam quickly. I have seen boilers with drums piled one on top of another where there would be ten tons of water to heat up. The question of how much water you have in your boiler beyond the amount necessary to keep the heating surfaces wet is one of how fast you want to raise steam. When you begin to fire up, if you are going to be in a place where you have to suddenly raise steam, to do it in fifteen minutes or so you want very little water in the boiler. If, on the contrary, you have a rolling mill that is running night and day there is no objection to firing up the boiler twelve hours before you start the mill. It is a question there of reserve capacity. The question is how much of a reserve