distributing daily scores of thousands of feet of gas through 30 odd miles of main, the furthest point being 8 miles from the station, the trunk line being but a 2-inch pipe. The whole of the gas goes through that 2-inch pipe. The reason is that they have 200 pounds of pressure back of it. That simply shows what you can do when working under pressure. It shows what efficiency, capacity, and delivery can be attained. That plant is the Pintsch plant in Chicago, from which is supplied the equivalent of a third of a million feet per day of ordinary gas. They have four compressors working all the time keeping the pipes full at say 200 pounds pressure. At the other ends of the lines there are tanks. and regulators which cut the pressure down from high to low, and do it perfectly well. At Danbury the regulator from the receiving tank cuts the pressure down at one drop from 40 pounds to 3 inches. They have a pressure record kept in the ordinary fashion. I looked over the runs for a year. They are just as good as the pressure runs that we get in ordinary gas works. They are not straight runs-I never saw any such anywhere-but they do not vary any more than ordinary pressure registers show. I think the experience at Pittsburg on natural gas is conclusive evidence that regulators are all right. The Welsbach people who put out thousands of them say they work perfectly well. They do not give any more thought to regulators than they give to the dependability of valves or any other such appliance. I did not mean to compare the delivery of gas to the delivery of water except in a general way. I know that no direct parellel is to be drawn. I refer to the general fact that almost every fluid-liquids, gases, and everything else is delivered under high pressure, and large capacity is thus secured from small tubes. In answer to Mr. Ferrier, I would say it would be my desire, in the adoption of such a distribution system, as far as possible, to have the local distributing mains low pressure, running a high tension feeder to the district, and putting on a district governor to reduce to the low pressure local system; but along the high pressure lines of such system I would not hesitate to put in individual house governors. The cost of compression and delivery through a few miles of pipe I think you will find, including interest on the investment in machinery, the power and the repairs, will fall within 2 cents per 1,000 on a long distance delivery. The extra attending labor is practically nothing.

MR. WITHERBY-I would ask the size of the receiving tank at the place where you estimate the daily consumption, and in which this high pressure gas is stored.

MR. SHELTON-The receiving tanks at Danbury are six feet in diameter and 30 feet long. There are two of them. There is a

valve by which they can switch off either while the other is being opened or fixed. I might add that the volume of business is about 5,000,000 feet of gas per year, and that Mr. Edgerton's statement to me was that he could just as well reverse the situation, and make all his gas at Bethel (a town of 3,500 or 4,000 inhabitants) and deliver the gas from there back to Danbury; in other words, the 2-inch pipe and the compressor would just as well supply gas for a town of 20,000 as for a town of 3,500; or that a 2-inch pipe and a compressor, costing $700 or $800, would take care of several times the amount of business he has had occasion to handle thus far.

MR. WITHERBY-If that is a success, it would give gas men cheaper storage. It looks to me as if the plan would bear investigation.

MR. SHELTON-I quite agree with Mr. Witherby that on the lines discussed, here is the opportunity and promise of increasing consumption and reducing cost, as the Danbury people have done. We know that the price of gas has gone down steadily year by year, and we know that we must reduce our investment, if possible, especially in street mains. I firmly believe that the time is coming, and is not far distant, when high pressure distribution will be very common, and, indeed, the natura! thing.

MR. WHEELER-Mr. Shelton has just taken the words out of my mouth as to the situation at Danbury. Mr. Edgerton made the statement to me that he could just as well supply Danbury, or a city three or four times as large, from Bethel, as to do what he is now doing. I think Mr. Shelton mentioned everything in connection with that undertaking except the fact that there is no drop in candle power, or no more than there is in distributing gas around the outskirts of our city.

On motion of Mr. Wheeler, a vote of thanks was passed to Mr. Shelton for his very instructive and interesting paper.

The President introduced Mr. Irvin Butterworth, who read the following paper on

VITRIFIED CLAY PIPE INSTEAD OF IRON FOR GAS

MAINS.

The idea of using vitrified clay pipes instead of iron for gas mains did not originate with the writer. It was proposed to him. by Mr. Henry L. Doherty, President of the Madison (Wis.) Gas and Electric Company. He afterwards brought it to the attention. of the President of this Association, who requested me to prepare a paper on the subject for this meeting, the author of the idea

having modestly declined to be the author of the desired paper thereon. I have accordingly consented to bring the matter before you to the best of my ability, this being the second time that I have. served, on an occasion of this kind, as Mr. Doherty's "Boswell."

The proposition that ordinary vitrified clay pipes, similar to those now commonly used for sewer construction, can be readily substituted, with great advantage and economy, for wrought and cast iron pipe for gas mains, appears, if not when first presented, then upon due investigation, to be entirely correct. While its correctness cannot as yet be proven by the citation of any examples of the successful use of vitrified pipes for gas mains, because such pipes have not as yet, to our knowledge, been employed, even experimentally, for that purpose; yet the apparent objections to the proposed system, that probably occur to some of you at first thought, disappear upon due consideration of the conditions to be met, and the qualities of vitrified clay pipe.

The suitability of vitrified clay pipes for gas mains is due to its possession of the following properties:

I. Cheapness; 2, durability: 3, strength; 4, non-susceptibility to electrolytic action; 5, slight susceptibility to changes of temperature; 6, non-porosity; 7, adaptability to the making of service connections by the use of specials or a small auxiliary distributing pipe of wrought iron.

We will consider these properties in the order named, and in comparison with those of iron pipe.

1. Cheapness. The following table shows the costs per foot of vitrified clay, cast iron, and wrought iron pipe at present market prices:

Vitrified clay pipes can be had, in quantity, in 4-foot lengths, and with large and strong sockets similar to the bowls of cast iron gas pipe, at approximately the above prices. The 4-foot lengths would, however, necessitate the making of three times as many cement joints in a line of clay pipes as in a line of cast iron pipes

of the usual 12-foot lengths. The following is, therefore, a rough but fair comparison of the cost of a mile of 6-inch vitrified clay and cast iron gas mains:

Fire Clay. Cast Iron.

Excavating and refilling trench, at 25c. per foot...$1,320 $1,320 Cost of pipe in trench, at 6c. and 35c. per foot..... 317 1,848 Cost of making 1,320 and 440 cement joints, at 25c.

Saving in favor of vitrified clay pipes, $1,311, or 40 per cent. For sizes of main larger than 6 inches, the saving would be still greater, being, for instance, in the case of a 12-inch main, more than 50 per cent.

2. Durability.-Vitrified clay pipes are even more durable than cast iron. They do not rust or corrode. No chemicals or substances in the earth, foreign or otherwise, seem to attack them in the least. They are practically indestructible, and retain their strength and non-porosity indefinitely. I recently examined a piece of vitrified sewer pipe that had been buried in the earth for 35 years, which, when cleaned, an experienced sewer pipe manufacturer said he could not distinguish, by appearance or any other test, from freshly made pipe.

3. Strength.-Vitrified clay pipe, while not as strong as cast iron, is nevertheless amply strong for gas mains; as they do not break or crush when used for sewers, why should they do so when used for gas mains? The tensile strength of vitrified pipe, either fire clay or shale, is astonishingly great. Edward Orton, Jr., Professor of Ceramics at the Ohio State University, recently made some careful determinations of the tensile strength of vitrified clay pipe. He found that ordinary single-strength, 6-inch, vitrified fire clay sewer pipes, with walls 5% of an inch thick, withstood an internal hydraulic pressure of from 90 to 120 pounds per square inch; while 6-inch, vitrified shale pipes withstood from 140 to 180 pounds, one piece not bursting even at the latter pressure. Twelve-inch, vitrified shale pipe, with walls 14 inches thick, have withstood an internal pressure of 220 pounds. A 2-foot length of 4-inch vitrified, fireclay pipe, selected at random, with walls 1⁄2 inch thick, was supported at both ends, and a weight of 2,800 pounds was suspended from the middle of the pipe before it broke. Vitrified clay pipe may be brittle, as are also cast iron pipe, and like them can be easily broken by a sharp blow, such as they would never receive when in use as gas mains, but they are extremely

strong, and do not readily break under a steady strain, such as they might be subjected to when buried in the earth. The difference between them and cast iron pipe in this particular is not great, and the advantage is only slightly on the side of the cast iron.

4. Nonsusceptibility to Electrolytic Action.-Vitrified clay pipes are not in the least degree liable to injury from electrolysis, whereas, as is well known, the electrolysis of iron pipes has become a most serious matter.

5. Slight Susceptibility to Changes of Temperature.—The relatively high coefficient of expansion of iron constitutes a serious ob· jection to the use of this material for gas mains. Iron mains frequently break, and their joints generally leak, on account of the excessive expansion and contraction of the pipe, due to changes of temperature. On the other hand, the expansion and contraction of vitrified clay pipes buried to the usual depths of gas mains, would be very slight indeed, and in fact practically nil. The following is a table of the coefficients of expansion of the materials named:

Although the coefficient of expansion of vitrified clay has apparently never been determined, it is safe to assume that, inasmuch as it partakes more nearly of the nature of common brick than of glass, its coefficient of expansion is no higher than the average of the coefficients of these two materials, or say only one-third that of cast iron. Substantially this view is held by Prof. Orton.

The practical and economic advantage that vitrified clay gas mains would have over iron in this particular need not be dwelt upon here.

6. Non-Porosity.-Vitrified clay pipes are, except possibly at enormous pressures, absolutely impervious to gas, while cast iron pipes are more or less porous at ordinary gas pressures. The vitrified clay pipes subjected by Prof. Orton to 180 pounds of internal hydraulic pressure showed no trace whatever of sweating.

7. Adaptability to the Making of Service Connections by the Use of Specials, or by a Small Auxiliary Distributing Pipe of Wrought Iron. It is probable that a successful method of tapping vitrified clay mains for services, and of connecting the services to the mains, would soon be forthcoming; but in laying new mains, especially the smaller sizes, it would probably be best to place a