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By D. C. McKeehan

The importance of properly bonded rail joints has received the attention of The National Research Council, whose committee will investigate several methods now used and determine the merits of each as applied to street railways. The results of this investigation should be appreciated no less by the mining industry. Literature on the subject of bonding mine tracks agrees, as a rule, "that the work is poorly done." With present day facilities there is little excuse for inadequate track conductivity, and a job well done must be maintained in order to realize results. Many years ago The Union Pacific Coal Company installed their first haulage locomotive, and at that time used the channel pin bond for joining the rails. The system utilized 500 volts and the, relatively small current for a large amount of power, undoubtedly, contributed to the success of the system. The bonding of both rails was considered imperative in those days, while now the bonding of one, rail is considered sufficient in most instances. The recent installations utilizing 250 volts and correspondingly heavier currents required a more effective method of joining the rails for use as an electrical conductor. The company has used the arc-weld bond since its introduction in 1919. The art of electric welding found great favor for various methods of doing the work. The first arc-weld bonds were placed on the outside of they ball of the rail, but the bonds were ill-adapted to rails lighter than sixty pounds per yard, and the results were that grooved locomotive wheels or derailed cars removed the bonds. Familiarity with the process of electric welding brought forth numerous schemes for joining the rails. In one, instance the rails and splice-plates were welded together and with excellent results for a short time. Track movement and vibration finally broke the welds and the method was dis¬carded. Another scheme consisted of placing a channel pin over each end of an annealed copper wire about twenty inches long. The idea was to develop some way of using short lengths of scrap wire. The pin and wire were then welded to the base of the rail. Numerous joints made in this way are still intact, but successful welds were so exceptional that the practice was abandoned. Some of these bonds were welded to the web of the rail, with the result that practically all rails broke at the weld; however, this is our only record of broken rails with arc-welded bonds. At one time a quantity of No. 2 bare iron wire wasp available and was tried as a bond and proved very satisfactory. Two or three strands twenty inches long were used and were welded to the base of the rail. The method was cheap and effective and of some merit for light rails on temporary track. The use of iron wire was criticized because it did not give a balanced circuit; that is, one having equal carrying capacity for trolley and track circuits; and I am of the opinion that this is not always necessary. The total length of bond that is in circuit is so small that it contributes very little additional resistance to the complete circuit consisting of trolley wire, rails and bonds.

Jan 1, 1923

By W. G. Harbert, C. Upthegrove

DURing the past year considerable work dealing with physical properties of cartridge brass was done at the University of Michigan in cooperation with the Ordnance Department of the U. S. Army. This paper gives some of the data bearing on the effect of the anneal, previous to the final reduction-or rolling, on the physical properties, particularly the hardness. Various phases of the subject of physical properties of cartridge brass have been presented by different investigators. Mathewson and Phillips1 refer to the work of Grard, in 1909, as the first systematic presentation of the relation between temperature and time of anneal, changing of physical properties and microstructure, and the previous reduction by cold rolling. They discuss the relation between time and temperature of annealand the previous reduction by cold rolling; also the relation between physical properties and grain size of annealed brass. The degree of deformation previous to the annealing was found to determine the temperature at which recrystallization and corresponding changes in physical Properties would take place. relation between grain size and Brinell hardness, found the hardness for low-temperature annealing to be dependent on the previous degree of reduction, while for anneals above a certain temperature the hardness after the anneal was independent of the degree of reduction. Actual differences in hardness, due to the degree of reduction, disappear only on annealing at 600" C. or above; though the differences for metal subjected to different degrees of reduction and annealed at temperatures between 350" and 600" C. were found to be relatively small. In their determination of the relationship of grain size to Brinell hardness, Bassett

Jan 1, 1923

LIST OF THE MEETINGS OF THE INSTITUTE AND THEIR LOCALITIES FROM ITS ORGANIZATION Transactions Number Place Date Vol Page 1 Wilkes-Barre, Pa May, ?71 1 3 2 Bethlehem, Pa August, ?71 1 10 3 Troy, N Y November, ?71 1 13 4 Philadelphia, Pa February, ?72 1 17 5 New York, N Y May, ?72 1 20 6 Pittsburg, Pa October, ?72 1 25 7 Boston, Mass February, ?73 1 28 8 Philadelphia, Pa May, ?73 2 3 9 Easton, Pa October, ?73 2 7 10 New York, N Y February, ?74 211 11 St Louis, Mo May, ?74 3 3 12 Hazleton, Pa October, ?74 3 8 13 New Haven, Conn February, ?75 3 15 14 Dover, N J May, ?75 4 3 15 Cleveland, 0 October, ?75 4 9 16 Washington, D C February, ?76 4 18 17 Philadelphia, Pat June, ?76, 5 3 18 Philadelphia, Pa October, ?76 5 9 19 New York, N Y February, ?77 5 27 20 Wilkes-Barre, Pa May, ?77 6 3 21 Amenia, N Y October, ?77 6 10 22 Philadelphia, Pa. May, ?78 6 18 23 Chattanooga, Tenn May ?78 7 3 24 Lake George, N.Y. Oct. ?78 7 25 Baltimore, Md. Feb. ?79 7 26 Pittsburgh Pa, May ?79 8 27 Montreal, Canada Sept, ?79 8 28 New York, N.Y. Feb, ?80 9 29 Lake Superior, Mich Aug, ?80

Jan 1, 1923

H. C. GLAZE: There is no question in my mind that the day of direct current distribution is practically ended so far as large coal properties are concerned. Another thing that Mr. Drennan touched on that is of the utmost importance, is that of voltage-voltage to the various pieces of equipment inside the mine. You all know how expensive it is to have motors in operation in important places where the voltage .is about half that which the motor should have. This is particularly true in the direct current system. It slows down production, causes burnouts and destruction to apparatus, and is a question that you men have got to go into. It costs a great deal of money, as Mr. Drennan pointed out, to take care of this. The wires are large and cumbersome, while; on the other hand, with an alternating current system you can use a minimum amount of wire. We have installed this class of equipment with so-called "pick-proof" cable of 2,200 volts down slopes, and I have never heard of any trouble whatsoever from this cause.

Jan 1, 1923

By A. L. Jones

The subject assigned to me of "The Power" Problem of the Mine" is so broad that I have decided to confine myself to the question of the power supply itself, rather than the application of electricity throughout the property. We will look over certain economic aspects of the problem, particularly in the way it affects the mine manager or executive and his attitude toward the power plant. The accepted method of power application to the mine is by electric power, and the experience of each of you is that the job is never complete as you are always undertaking some further electrification which necessitates the stiffing up the power house to care for the additional load. The mine executive, then, is wrestling almost continuously with the problem of his power plant. Either it is overloaded and must be enlarged and rebuilt; or its operating costs are excessive; or it breaks down and limits coal output; or some one wants to sell new and improved machinery, until the manager almost hates the thought of such a restless part of his property. If he purchases power, every day new uses for it seems to be found. In many ways this unrest is due to short-sighted policy toward the problem, and the tendency when the problem of extension has to be met, to dispose of it in the cheapest way and without thought as to where the future is leading. The day when each opening had its own boiler plant, steam hoist, steam driven fans, steam pumps, steam loaders, etc., seems to be far behind us. The recognized method of power distribution today is by electric power, except for rather limited applications of compressed air; most of which is electrically compressed. During fifteen years contact with mines of Colorado and Wyoming the writer has seen nearly every mine power house double or triple in capacity or abandoned in favor of purchased power, worn. out and inefficient machinery thrown out, isolated boiler plants dropped, seam pumping at great depth changed to electric drive, all resulting in greatly reduced labor and fuel costs. Power costs, which in such isolated plants were considered normal, would be unthinkable today. One property where the main power supply was by compressed air from steam driven com¬pressors used under boilers 8.35 per cent of all the coal mined. The cost of power was 12 1/2 cents per ton of coal mined. Another property of four openings, each with its own boiler plant and usual equipment of hoists, pumps, etc., had a power cost of 10.3 cents for each ton mined; and these were days when you did not get very high prices for coal. Another property operating two mines mostly by steam used 11.1 per cent of the coal output under their own boilers and the power cost was 19.45 cents for each ton mined. Each of these properties is now electrified and power costs are from 3 to 4 cents per ton, and the fuel burned runs from 1 to 2 per cent of the output. With the broadening market and high prices for slack coal and the high prices for labor in boiler and engine rooms, the cost of steam is reaching a high figure, and efforts must be made to keep this down, by more efficient steam production and by utilizing this steam in better machinery which will increase the work done by each pound of steam. It must not be overlooked either, that the plant which is very wasteful of fuel is usually a pretty old one and one far from reliable. In a general way the more efficient the plant, the greater its reliability. Ample and reliable power supply means ability to get out coal when there is a market. The increasing use of purchased power is largely due to changing conditions which are tending constantly to push up the cost of power, unless the most efficient machinery is used and large scale production possible. The

Jan 1, 1923

||Abad, Leopoldo F, College of Min, Univ of California Berkeley, Cal '23 ||Abarquez, Ramon F, Met, Bureau of Science Manila, P I '24 ||Abbey, Robert Graham, Student, Case School of Applied Science Cleveland, Ohio '21 Abbott, A N , Mines Supt , Mazapel Copper Co , Ltd Concepcion del Oro, Zacatecas, Mexico '23 Abbott, Clarence E, Gen'l Supt, Iron Mines Div, Tenn Coal, Iron & R R Co, 1405 Minnesota Ave, Bessemer, Ala '04 Abbott, Louis Benjamin, Chief Engr, Consolidation Coal Co, Elkhorn Div 'Jenkins, Ky '15 Abbott, Robert R , Met Engr, Peerless Motor Car Co Cleveland, Ohio '12 ||Abbott, Wells Osborn, Ray Consolidated Copper Co Hayden, Ariz '23 Abeel, George H, Jr, Cons Min Engr 4612 W 17th St, Los Angeles, Cal '18 Abel, Albert E, Asst to Pres, Valley Mould & Iron Corpn Sharpsville, Pa '19 ?Abeloff, Miran S Address Wanted '21 Abernathy, G E, Kansas State Teachers College Pittsburgh, Kans '20 Abey, Hiroshi, Min & Met Engr, Takata & Co, 2 Yeirakucho, Nechome, Kojimachi-ku,

Jan 1, 1923

TO THE BOARD OF DIRECTORS AND THE MEMBERS OF THE AMERICAN INSTITUTE OF MINING AND METALLURGICAL ENGINEERS Gentlemen -It is pleasant to be able to report that the year just closed has been a prosperous and successful one for the Institute As is shown by the reports of the Treasurer and the Finance Committee, the business affairs of this organization are in excellent condition With property valued at more than three-quarters of a million dollars, and with con¬siderable sums in various funds and endowments, it is possible to spend on each member of whatever class $22 65 each year, more than the maxi¬mum amount of dues received from any one, and substantially twice the average amount, $10.94, received from all To do this has required close management and a strict regard for our limitations In 1926, when the Budget was made up, the estimated expenditures for the work which it was felt the Institute must do exceeded the estimated receipts by some $14,000. At the close of the year, despite a` number of unexpected decreases in receipts, it had proved possible to accomplish substantially all the work laid out and close the books with the usual transfer of initia¬tion fees to the General Reserve, and still only reduce the cash balance $2,074 54. This was made possible by the hearty and loyal cooperation of the whole staff of employees and the extremely large amount of gratui¬tous service rendered by the officers, the members of the Divisions and technical Committees, and the membership generally Even so it was impossible, because of limitations of funds, to undertake many things it is highly desirable for the Institute to do, and it was necessary to refuse the publication of important papers and committee studies, because of the lack of funds.

Jan 1, 1923

By M. Mathieu

The Rove tunnel is the means by which the canal from Marseilles to the Rhone Riverl penetrates the hills of Nerthe, lying between Mar- seilles harbor and Lake Berre, Fig. 1. The canal will communicate at sea level with both terminals. The original project planned a lock near the village of Marignane; but observations, pursued for more than three years, showed that the water surface gradient would average only 0.015

Jan 1, 1923

By Walter Weeks

THERE is very little useful material in the litera-ture on the construction of manometers, so each experimenter must devise his own instrument. I have experimented for a number of years and have finally built one that is satisfactory. If we are to obtain accurate friction factors in mine-ventilation problems we must use accurate instruments. The most simple and convenient instrument for the mea-surement of small pressures is the inclined manometer or U-tube. By changing the angle at which the tube is set, any desired magnification of the pressure reading may be obtained. The first question in regard to the manometer is: What liquid shall be used? Alcohol, in my opinion, is the best. It does not cling to the glass and it does not attack the rubber tubes. The next problem is the setting of the instrument at the proper angle. One method is illustrated in Fig. 1. The base plate AC is made horizontal by a level bubble. The plate AB, which carries the U-tube, is hinged at A. The angle z which AB makes with the horizontal may be made any value by pinning the end B at the calculated position on the arm CD. Such an instrument may be designed to read directly in inches of water if a liquid of constant specific gravity is used. If the specific gravity varies, a calculation is necessary to convert the reading into inches of water.

Jan 1, 1923

By Douglas Muir, Chas. A. Chase

The Aztec mine is not widely known, by reason of its isolation and the relative insignificance of its tonnage; financially, however, it has an enviable record and geologically it is extremely interesting. The town of Baldy, Colfax County, the mine camp, at an elevation of 10,000 ft. (3048 m.) is 8 mi. west of Ute Park, the terminus of a branch of the A. T. & S. I?. Ry. The mining tract was designated by the Maxwell Land Grant Co. as the Aztec Reservation, and lies on the east slope of Mt. Baldy, the summit of which, 12,491 ft. (3807 m.), is one of the highest in the state. Rich copper float was found on the northeast slope of the mountain in 1865, and discovery work was begun the next year. At the same time, gold placers were found on Willow Creek, on the southwest side of the mountain, and the Elizabethtown settlement followed shortly. Gold washing lasted many years. In 1867, placer gold was found also on Ute Creek, the tracing of which to its source led to the locating of the Aztec mine by Lynch, Dogherty, and Fosley in the following year. The early production came from the contact of shale and sandstone or from sandstone immediately above the contact. Exact record of production is lacking, but L. C. Gratonl gives estimates ranging between $1,250,000 and $1,500,000, of which about $1,000,000 was taken out in the first four years. After the exhaustion of the early bonanza, production continued intermittently until 1909, when the Maxwell Land Grant Co, undertook systematic development, through four adits at intervals of 75 ft. vertically or approximately 100 ft. on the dip of the contact, which was thought to contain generally a quartz-pyrite vein. The two intermediate adit? almost immediately reached ore, the most southeasterly in Fig. 2. This ore, however, was not mined until 1911-12; its grade was about $20 and

Jan 1, 1923

Abbey, Robert Graham, District Mgr. The W W. Sly Mfg. Co,. 50 Church St, New York, N. Y. '21 Abbott, A. N., Mines Supt., Mazapil Copper Co., Ltd ..Concepcion del Oro, Zac., Mexico. '23 Abbott, Argyle Campbell, Dev. Dept, E I du Pont de Nemours & Co, Wilmington, Del. '29 Abbott, Clarence E., V.P, Charge of Raw Materials, Tenn. Coal, Iron & R. R. Co, 1242 Brown-Marx Bldg, Birmingham, Ala. '04 Abbott, Louis Benjamin, Chief Engr., Elkhorn Div., Consolidation Coal Co, Jenkins, Ky. '15 Abeel, George H., Jr., Cons. Min. Engr Box 427, Santa Monica, Cal. '18 Abel, Albert E., Asst. to Pres, Valley Mould & Iron Corp Hubbard, Ohio. '19 Abel, Raymond L., Asst. Prof., Dept. of Pet Refin., Univ. of Pittsburgh Pittsburgh, Pa. '28 Abell, Leo M., Research Engr, Sullivan Concentrator Chapman Camp, B. C., Canada. '31 Abernathy, George Elmer, Prof. of Geol. & Min . Kansas State Teachers College, Pittsburg, Kans. '20 Aborn, Robert H., Research Lab, U. S. Steel Corp. Lincoln Highway, Kearny, N. J. '19 Abozeid, Mahmood, Dept. of Mines & Quarries Cairo, Egypt. '26 Abraham, Arthur W. Box 1466, Bakersfield, Cal. '20

Jan 1, 1923

Executive ROBERT E. TALLY, Chairman WILLIAM H BASSETT JOHN A. MATHEWS Louis S. CATER EDGAR RICHARD Finance HENRY KRUMB, Chairman H A GUESS H G. MOULTON Admissions ERLE V. DAVELER, Chairman GEORGE D BARRON H K MASTERS JOHN M. LOVEJOY P. A.-MOSMAN Alternates E. L. ESTABROOK C. E MEISSNER J. A. SINGMASTER FRED H. KAY

Jan 1, 1923

By C. D. Woodward

The Anaconda Copper Mining Co. purchases 25,000 kw. of electric power for its mining operations at Butte, Mont. This power is delivered, over duplicate feeders, in the form of 60-cycle, 2400-volt, three-phase current, to five compressor plants, where most of the energy is used for driving air compressors. At the compressor plants are located the switching apparatus for controlling the 2400-volt power and distributing it to the various mines. At these points, also, there are a number of motor-generator sets for converting the alternating current to 275-volt direct current for the haulage systems. Pole lines convey the powcr from the compressor plants to outdoor transformer substations at most of the mines. When it is not economical to distribute the power at the lower voltages in the mines, transformers and motor-generator sets are placed at strategic points underground. All power is purchased on a maximum-demand basis; therefore there is installed at one of the compressor plants an eight-element totalizing graphic wattmeter. This instrument records simultaneously the value of all power taken at the numerous points of delivery, which not only climinates the diversity factor but permits load dispatching between compressor and pumping plants, and thus materially reduces the maximum demand from the power system. As most of the mine hoisting is done by 90-lb. compressed-air winding engines, the air-compressor equipment for the winding engines and mining operations is quite extensive. The standard air compressor has a rating of 7500 cu. ft. per min. of free air, and most of the compressors are directly connected to synchronous motors. The synchronous motors are designed for 80 per cent. loading power factor, thus facilitating power-factor correction of total mine load. Consequently by cooperation with the power company, the voltage of the power received at the compressor plants is constant. In the mines there are installed an induction motor load of approxi-mately 10,000 hp., and 4500 kv.-a,, in transformer capacity. It is the practice to install 2200-volt motors in the mincs, except those rated below 50 hp, hence there are in operation underground about 5000 hp., in the

Jan 1, 1923

By A. S. Richardson

THe conditions that make necessary the mechanical ventilation of the Butte mines of the Anaconda Copper Mining Go. are due to a number of causes, all of which are incidental to the depth at which mining operations are now carried on, The main object to be accomplished, of course, is the reduction of the temperature and humidity of the air in the working places. Ventilation fans, both surface and underground, have been used for many years, but increasing depth has made the problem much more difficult. Further improvement in both ventilation equipment and methods, therefore, became necessary; and it is the purpose of this paper to describe the work planned and done under the improvement program. The mines of the district have been frequently described in various technical publications, so a description is unnecessary here. From a mine-ventilation viewpoint, compared with coal-mine ventilation systems, the problem is complicated by the fact that the workings to be ventilated are situated on a large number of steeply dipping veins which frequently intersect and are faulted, and also by the fact that the extent, or existence, of orebodies is not definitely known in advance of actual development work. For these reasons ventilation work cannot be planned in advance of actual operations, nor can such regular systems of ventilation as are used in working the more uniform and continuous bodies of coal be developed. When operations are conducted at a normal rate, about 10,000 miners are employed on two shifts, so that about 5000 men will be underground at one time. But as ventilation is necessary to reduce high temperature and humidity due, mainly, to natural causes, the quantity of air per man per minute is not a governing consideration in determining ventilation requirements. Most important among the numerous sources of heat and humidity in the mines are: heat generated during decay of mine timber; heat and humidity given off by mine rock and water; heat generated by oxidation of sulfide minerals; heat given off by electrical equipment; heat generated by mine fires (in certain localities).

Jan 1, 1923

FOR some time past keen interest has been shown in both America and South Africa in the mining drill-steel problem. This interest has extended to Australian mining fields, and Australian drill users, ever desirous of increasing efficiency, are vigorously attacking the problem. The writer has recently been engaged in the investigation of the problem on two of ,the biggest mining fields in Australia, and has formed very definite conclusions concerning the causes of many drill-steel casualties. He puts these views forward in the hope that they may be of interest to, both drill manufacturers and drill users. The subject is here dealt with mainly from the aspect of the properties of the steel and the modifications of these properties whensubjected to various manipulations. It is generally admitted that the drilling machine has greatly increased in power and efficiency during recent years, and the consequence is that the machine is demanding better service from the steel. This is being impressed on the drill users by an increase in steel casualties. This fact has led many mining people to the view that the machine has developed so rapidly that the steel maker has not been able to keep pace, and that consequently the steel isfailing by fatigue 0:1; so-called crystallization. This view is rather depressing. The writer, on the other hand, is inclined to discountenance fatigue as a serious factor under good normal working conditions where the steel is carefully manufactured and supplied to the user under suitable structural and sound conditions, and has subsequently received kind treatment at the hands of the drill sharpener and the drill user.It is not reasonable to attribute failures to fatigue until it has definitely been proved that the steel is fundamentally sound and is in the best structural condition to resist the stresses it is called upon to withstand, and, this being so, that all fundamental principles of...

Jan 1, 1923

ALABAMA Aldrich.-Lloyd, T. W. Ashland.-Downs, F. G. Geary, E. S. Auburn.-Brown, R. L. Bessemer.-Abbott, C. E. Ball, T. L. Ferguson, V. Salmon, H. S. Stuart. Q. W. Birmingham.-Adams, J. H. Aldrich, T. H. Aldrich, T. H., Jr. Allen, A. W. Armstrong, W. D. Ball, E. M. Bonnyman, J. Bush, M. W. Crawford, G. G. Davis, C. B. Ellis. E. E.

Jan 1, 1923

By F. W. Guernsey

Of all the elements, sulphur occupies a place by itself. It is mined in situ, in such quantities and of such purity that, as regards the tonnage produced, it is the first of any element on the list. Iron and coal the great tonnage producers, are combinations of elements, while sulphur is mined and marketed almost chemically pure. It is sold, in large quantities, commercially, calling for a purity of 99.5 per cent while for medicinal purposes, the Pharmacopoeia requires only 99 per cent. purity. It is a very common commodity, and like many common things is of extreme importance, in the progress of our civilization. The substance has been known from the earliest times, the word sulphur being derived from the Sanskrit Culvari", hence the Latin Sulphur. Commercially it is also called brimstone, this word being a derivative of the Anglo-Saxon Bryne Stane or burning stone. From our younger days, we have been more or less familiar with the mineral. On the spiritual side being threatened, if we did not behave ourselves, with an ultimate consumption in a lake of fire and brimstone, (which in moments of reflexion was not pleasant to contemplate) while our bodily ills were taken care of by inward applications as a spring medicine. In both instances, the effect required, was generally attained. Sulphur occurs in nature, both free and in the combined state, it being estimated that it forms, over one tenth of one per cent of the first ten miles of the earths surface. (I do not know who did the estimating and it is not guaranteed).

Jan 1, 1923

THE following really forms the second part of, or a sequel to, a paper, " Ventilating Metalliferous Mines: a Method of Attack," read before the Broken Hill Branch of the Australasian Institute of Mining and Metallurgy in May, 1920. In that paper the writer advocated a consideration of the question of ventilation in metal mines from a different aspect to that 'which had hitherto prevailed locally. Various factors regarded as having an important bearing on the subject were set forth, together with the results of observations made during ventilation tests carried out at the mining department of the Zinc Corporation.During the subsequent discussion the question was raised of the possibility of any practical application of the method of attack described, and also whether the theoretical considerations mentioned were likely to be of any real utility to the mining engineer engaged in ventilation work in a metalliferous mine.

Jan 1, 1923

ALABAMA Aldrich -Thomas, D A Altoona -Cain, J Anmston-Cowie, L K Walmsley, W N White, H E Bankhead -Terentieff, V E Bessemer -Abbott, C E Ball, E M McKenzie, W C, Jr Mitchell, F R Morgan, C Thompson, N E Birmingham -Adams, J H Adler, J E Aldrich, T H Aldrich, T H , Jr

Jan 1, 1923

By F. L. Wolf, A. A. Grubb

The tests here described were rrlade to obtain information regarding costs, efficiency, etc. of baking cores in an oil-fired oven and two electric ovens, which were installed, early in 1920, in the core room of The Ohio Brass Co. and were used almost continuously during the rest of that year. Operating costs were rather high so a complete test was undertaken early in 1921. The ovens will be referred to as Nos. 1, 2, and 3. Nos. 1 and 2 are electric ovens of different makes while No. 3 is an oil-fired oven made by the firm that made No. 2. The three arc. equipped with similar ventilating devices. They have full-height doors at front and rear. The cores are placed on iron racks, which arc lifted by Cowan trucks and rolled into the ovens through the front doors. When baked, they are removed through the rear doors. Fig. 1 shows the general plan of the elecric ovens while Fig. 2 shows the plan of the oil-fired oven. Oven No. 1 is 91 in. (231 em.) wide, 83 in. (210 em.) high. and 79 in. (200 cm.) deep, inside measurements. The walls are constructed ill panels about 18 in. (46 cm.) wide and 43/16 in. (10.6 em.) thick, packed with blocks of insulating material and covered with sheet iron. Thc concrete floor oil which the owns set is 13 in. (33 cm.) thick. 4 recess about 5 in. (13 cm.) deep was cut in the floor to provide room for the heating units. Channels and plates supported on I beams serve as supports for the trucks and racks. The ventilating system consists of a Sirroco No. 11/2 fan, connected so as to draw air from the top of the oven or from the room, through damper C, and to deliver it either to the bottom of the oven or to the floor; the delivery is controlled by the vane A. The fan 2nd pipes are covered with 1/4-in. (6.3 mm.) asbestos-cement lagging. The heating units have a capacity of 91.4 kw. and arc located along

Jan 1, 1923