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By L. P. Durham

DuRing the early mine development period, 1929 and the first part of 1930, a 300-ton pilot-plant concentrator was built at Nkana mine of the Rhokana Corporation, Northern Rhodesia. This plant operated from May 26, 1930 until Oct. 26, 1931, treating 101,080 tons of Nkana ores and producing 4372 tons of concentrate. The plant was built, primarily, as a test unit to determine the grinding characteristics, floatability, etc. of the Nkana ores and other ores of the Rhodesian copper belt and to supply sufficient data on which to base the design of a 5000-ton concentrating plant at Nkana mine. The test unit operated wholly on development ores and no attempt was made to grade or select the ores from any section of the mine. The average assays for the 17 months of operation are given in Table 1. The first ground was broken for the 5000-ton concentrator during June, 1930, and the construction of the plant was completed in November, 1931. The plant started on Dec. 10 and has operated continuously since that date: The whole of the concentrating plant is compact and closely connected, yet with sufficient space for expansion of all sections up to 20,000 to 25,000 tons per day capacity. Mining operations are carried on along a length of about four miles on the easterly limb of the Nkana syncline. This length includes the North orebody, from which all production has thus far originated, and the Mindola orebody, now being developed for production. The ore-bearing measures in the North orebody are leached for some 75 ft. below the surface; the oxidized zone varies in vertical extent from 100 to 150 ft. Practically all the ore below the 200-ft. level is sufficiently

Jan 1, 1935

By Oliver Bowles

DISCUSSIONS of trade and commerce are generally more comprehensive today than in the past; the problems are approached with a vision unrestricted by national boundaries, and broad enough to comprise the entire world. The extent to which the limited viewpoint that has characterized past ages is yielding to an economy of world-wide scope is exemplified by the Atlantic Charter which blazes a trail in the direction of trade principles that aim to preserve the interest of each individual country in the commonwealth of nations. Its fourth article promulgated the principle that all nations should have access on equal terms to the trade and to the raw materials of the world which may be needed for their economic prosperity. Future developments in reciprocal international trade may have some effect upon the flow of nonmetallic minerals but such effects are not likely to be great because tariffs and trade policies have not affected that flow profoundly in the past. Nevertheless conditions may change and new problems may arise demanding important decisions. Sudden changes are not to be expected, but rather an orderly evolution in which national interests will merit due consideration in establishing broader policies.

Jan 1, 1945

By AIME AIME

PLANS are now well advanced for the joint meeting of the Institute and over a dozen other engineering societies in Chicago during the week beginning June 26: Engineers' Week at A Century of Progress. All engineers planning to visit the Fair will find it to their advantage to be present at this time so far as the Chicago attractions are concerned, and Eastern members will also have the advantage of special transportation arrangements on June 24 and 25. The tentative program is given at the bottom of the next page. Monday morning, June 26, will be reserved for registration of members and guests and the Woman's Auxiliary at the Stevens Hotel, where special rooms will be provided. A luncheon will also be served there, and in the afternoon, a technical session on nonmetallics. Instead of having the big family dinner that evening at the Stevens, as at first proposed, the local committee has planned to have it at the Fair Grounds, where special facilities have been arranged. A meeting of the Board of Directors and a few invited guests will precede the dinner. All members and guests are likely to be interested in visiting the Museum of Science and Industry, so that will be the sole event on the program for Tuesday morning, June 27. The big attraction there at present is the model coal mine, the first operative coal mine ever built for exhibit purposes. It is based on the Deutsches Museum mine at Munich, but goes far beyond that in realism, and takes the visitor on an extended tour underground. It shows him in half an hour more types of modern mining machinery and coal geology than he would be likely to see in a week's underground study in the coal fields. The Institute members will be the first group to go through this mine.

Jan 1, 1933

By C. C. Harris

An analytical solution of the integro-differential equation of batch grinding is proposed as a first appoximation to the xYt surface. The size distribution equation (xY plane) is a three parameter equation previously suggested. Possible refinements are outlined. Comminution kinetics research is presently following several related courses. Some are equivalent, in that they represent different ways of viewing the same facet of the problem, though the entire endeavor cannot be described as being completely integrated. The purpose of this note is to propose and discuss a framework into which the various approaches might be fitted. This must clearly be founded upon an analysis of the xYt surface.' (See also Fig. 1 of Reference 26.) The investigations referred to above comprise mainly researches into the following: (1) The kinetics of the creation of the finer sizes during relatively small grinding times. This is the Fahrenwald-Arbiter-Bhrany 2-3 approach which leads to equations equivalent to a special case of the charles4 relationship. It emerges that initial production of fines follow essentially zero order* kinetics. (2) Disappearance kinetics of the coarser fractions. This appears to be a first order relationship.5-6 (3) Prediction of the xYt surface via the selection and breakage functions utilizing computer-programmed or approximate solutions of the integro-differential equation of batch grinding.5,8-17 A recent discussion by Mika et al.5 references the relevant literature up to about 1966. In addition to these main-stream researches there is some work on the minor topic of extremely long grinding time considered as a limiting case.18-19 The field is supported by investigations into the size distribution of fragments produced by breakage processes, some of this work being most valuably statistical-mechanical in nature.20-25 Better fitting equations, however, are obtained by statistical and curve-fitting methods.26 This

Jan 1, 1969

By R. A. RAGATZ

THE preparation of specimens for microscopic examination from metal articles of relatively large cross-section offers no particular difficulty. It often happens, however, that articles submitted for examination are so thin that specimens satisfactory for microscopic examination can not be successfully pre- pared by the methods commonly employed when working with larger articles. Ordinarily, the preparation of metallographic specimens involves the following operations : (1) cutting the small specimens to be examined out of the larger mass of metal, (2) cleaning and electroplating, (3) mounting to furnish support during the grinding and polishing operations, (4) grinding and polishing to produce a scratch-free surface, (5) etching and drying. All of these operations must be carried out in such a manner that when the specimen is finally examined under the microscope, the structure seen is a true and well-defined representation of the structure that the larger mass of metal possesses at the place where the small specimen was removed. It is important that the deformation involved in cutting out the specimen be as slight as possible, in order that the subsequent grinding and polishing operations will completely eliminate the cold- working effects in the vicinity of the cuts. It is also important that the specimen never be allowed to attain a temperature high enough to alter its structure; the maximum permissible depends on the metal being handled. With some metals, zinc for example, consider- able care must be taken to avoid heating; with other metals, annealed steel -for example, no particular pre- cautions need be observed because there is no tendency for structural change to occur at relatively low temperatures.

Jan 1, 1929

By AIME AIME

FEW indeed are the sections of the country where trained or partly trained workers have not already been hired by a war industry plant or will be within the near future. Yet right in the midst of the heavily industrialized East lies the anthracite area, home of a million people, whose productive power has persistently been by-passed either by private industry or by the Government Plant Site Board. The chief reason given for not locating war plants in the area is that it is not within the strategic zone, but in numerous instances elsewhere this rule has been waived. Furthermore, the anthracite region is well protected on all sides by mountains and is at all points more than 100 miles inland. Continued depression in the anthracite industry and a crippling blow dealt by the war emergency to the production of silk and rayon goods, the chief manufacturing activity of the area, have resulted in a heavy migration, particularly of trained young workers, into near-by industrial areas. At least 50,000 people are currently unemployed, with the likelihood of an increase in coming months, and as many families are on relief.

Jan 1, 1942

By G. R. Speich

The age-hardening of Fe-18 to 21 pct Ni marten-sites containing small amounts of titanium, aluminum, copper, or molybdenum has been studied by hardness measurements, transmission electron microscopy, extraction replicas, and X-ray and electron diffraction. Electyon-probe microanaly-sis of the extracted precipitates was also performed. The effects of temperature and composition on the aging kinetics have been studied in detail for Fe-20 pctNi-Ti martensites. All the martensites hardened on aging at 400" to 500 "C with a single aging peak. In the Fe-20 pct Ni-Ti martensites hardening was associated with the formation of a fine dispersion of NisTi. No precipitation was observed in an Fe-21 pct Ni-2.6 pct A1 alloy, although the hardness increased from 327 to 545 Dph during aging at 500°C. Copper was precgitated from an Fe-20 pct Ni-10.7pct Cu alloy, at least during the later stages of age-hardening. Hardening in an Fe-18 pctNi-5pct Mo alloy was associated with the precipitation of an intemzetallic compound tentatively identified as NisMo. The formation of austenite and the recovery of the defect structure of the martensite occur simultaneously with the normal precipitation processes &ring aging of these alloys. THE age-hardening of substitutional iron-base martensites is an important subject for study since age-hardening is one of the principal means of strengthening the substitutional iron-base martensites in precipitation-hardening stainless steels1 and maraging steels.a~4 In contrast to Fe-C martensites, these martensites are relatively soft and ductile in the as-quenched condition, due to the low solid-solution hardening effect of the substitutional elements as compared to carbon. Also, these martensites are hardened by aging at low temperatures in contrast to Fe-C martensites which generally soften on tempering. Titanium and aluminum, singly or in combination, as well as copper and molybdenum, have been the principal alloying additions to stainless steels to obtain an age-hardening reaction.' Ti-A1 or Co-Mo-Ti combinations have been used in the case of maraging steels.3"4 The present work has been confined to a study of the age-hardening characteristics of an Fe-18 to 21 pct Ni martensite to which small amounts of titanium, aluminum, copper, and molybdenum were added in order to study the effects of each alloying element separately. The age-hardening characteristics of these alloys were studied by hardness measurements, transmission electron microscopy, extraction replicas, and X-ray and electron diffraction. Electron-probe micro-analysis of the extracted precipitates was also performed. The types and dispersion of precipitates, the formation of austenite, and the recovery of the defect structure of the martensite all were studied. EXPERIMENTAL PROCEDURE Alloys. The compositions of the alloys studied are listed in Table I. The level of 18 to 21 pct Ni was chosen to assure complete transformation to martensite on quenching and is the same nickel level used in maraging steels. The concentrations of titanium, aluminum, copper, and molybdenum were chosen after a study of the and Fe-Ni-MO' ternary diagrams indicated how much of each alloying element could be dissolved in austenite. Alloys with 2 and 4 pct Cu were also studied, but these did not show precipitation hardening at the nickel levels studied and will not be discussed further. The alloys were prepared from electrolytic iron and high-purity* nickel, titanium, aluminum, copper, and molybdenum by vacuum melting of 20-lb heats. These were vacuum-cast into two 8-lb ingots. The ingots were hot-rolled at 1100°C to 1/2-in. plate and subsequently cut into 3/8-in. cubes. The cubes were sealed in evacuated quartz capsules and solution-treated for 16 hr at 1100°C, except for the Fe-20 pct Ni-10.7 pct Cu alloy and Fe-21 pct Ni-2.6 pct A1 alloys which were solution-treated for 16 hr at 1300" and at 1250"C, respectively. Metallographic examina-

Jan 1, 1963

By Cyril S., Smith

THE phenomenon of air-hardening is well known in connection with special steels. It occurs when the rate of decomposition of austenite to marten- site is so retarded that it takes place on free cooling in air rather than on more rapid cooling in a quenching bath. If an air-hardening steel is quenched sufficiently rapidly it will remain in the soft austenitic state, while if it is cooled very slowly it will again become soft owing to growth of the carbide particles. It depends on a critical adjustment of the decomposition velocity and diffusion rate, and such alloys are rather rare, especially in the non-ferrous field. In carrying out some experiments on some copper- rich copper-cobalt alloys, the author found that these possess very marked air-hardening properties. The alloys are covered by a patent issued to M. G. Corson (1,723,022-1919), which states that an alloy containing between 2 and 5 per cent cobalt is hardened by simple quenching from above 850° C.

Jan 1, 1930

By JOHN R. SUMAN

OVERWHELMING proof of the importance of oil in a modern national economy is afforded by the present European War. Treat¬ies and national boundaries have been cynically violated to secure greater supplies of the precious fuel. Petroleum substitutes have been desperately, and far from successfully, sought. The whole German military theory of the drang nach Osten, the drive to the East, is directed at cutting the British supply of oil and securing a supply for Germany. This is a war of machines, and the machines of war feed hungrily on oil. In view of this fact, it is surely comforting to know that we are living today in a nation which has surpassed all the rest of the world not merely in unearthing the raw supplies of petroleum which lie beneath its surface but also in every phase of the industry in mining, refining, processing, production, and distribution.

Jan 1, 1941

By Leon W. Dupuy

Many articles have been written describing peculiar and particular types of drilling. Little correlation has been made between the character of ground to be drilled and sampled and the type of drilling most desirable for procuring satisfactory samples. In development work, the engineer and metallurgist often desire the recovery of a sample in as physically natural a condition as possible, particularly when the sample must provide material for process tests as well as chemical and physical analyses. This paper describes the results of experimentation in drilling unconsolidated materials carrying titanium minerals in the Magnet Cove area, Ark. The drilling was most difficult in that the ground varied much in consistency, and it was vitally necessary to recover a physically natural sample. Ordinary churn drilling recovered a sample that could be analyzed chemically, but the sample was not in its natural state. The problem was successfully solved by utilizing and further developing methods used in the oil and clay industries.

Jan 1, 1949

D. M. Riordan has been appointed a member of the Institute Com¬mittee of the Engineers' Reserve Corps movement. Our Committee, therefore, now consists of Henry S. Drinker, Chairman, Messrs. Arthur S. Dwight, Warren A. Wilbur and D. M. Riordan.

Jan 1, 1916

By R. H. Cox, A. S. Allen, James Paone

The southwestern Illinois communities of Belleville and Maryville lie within the greater metropolitan area surrounding St. Louis. Missouri. They also lie within that part of the Illinois coal basin where the Number 6 coalbed has been mined for more than a century. About half the coal was left as pillars to support the ground surface. Years later, however, damaging movements are affecting buildings, streets, and public utilities in some areas. They are generally believed to be related to abandoned mine workings. The threat of continued or increasing incidence of damage raises the need to explore other subsidence-control measures for protecting affected areas with high population density. Because of experience gained in a subsidence-control program of backfilling abandoned coal mines in the Applachian region and in Rock Springs, Wyoming, the Bureau of Mines was called upon to investigate the subsidence occurrences at Belleville and Maryville, and recommend protective measures. Funds ware appropriated for the Bureau to initiate subsidence-control projects at two residential sites in Belleville and one in Maryville. Subsurface investigation of the sites by diamond core drilling revealed two conditions that differ from those encountered at most sites of previous subsidence-control projects. The mine workings were found to be dry and the mine floor consisted of soft underclay which characteristically loses strength with increase of moisture. It had been anticipated that water would have percolated into the mine workings at one .or more of the sites through cracks resulting from subsidence. Under such conditions Bureau engineers believed that injection of mine waste by the pumped; slurry technique3 would provide support and stabilize any movements initiated by the softening of the clay. With discovery that the underclay deposits at the three sites have apparently not been exposed to water since the mines were operating, hydraulic backfilling of any type was considered inadvisable on the basis of present knowledge. To avoid introducing water, a portable pneumatic system is being devised for injecting minus 0.01 27 m (1/2 in.) mine waste into the mine workings. Machines for pneumatic backfilling have been used in Europe not only for subsidence protection but also for strata control, for reducing spontaneous combustion and methane accumulation, and as a means of waste disposal. The Bureau experimented with a pneumatic machine in the Northern anthracite field of Pennsylvania in the 1950's. Previously pneumatic machines have been installed in active mine workings discharging from horizontal pipelines which conveyed air- borne material into rooms to be filled. In the present adaptation to abandoned mines, the machine and air compressor will be operating at the surface, to impel material vertically down injection boreholes with sufficient air pressure to disperse fill material laterally in mine workings at the base of injection holes. Large diameter access and ventilation boreholes will be provided at one site for entry into mine workings to observe backfilling progress. The Belleville and Maryville projects are part of the Mined Land Demonstration Program of the Bureau of Mines. The Illinois State Geological Survey and Department of Mines and Minerals are furnishing technical support.

Jan 1, 1979

An index covering the papers presented at the 19 Open Hearth Conferences from the first meeting at Pittsburgh, April 15 and 16, 1925, through the most recent meeting in Detroit, April 16 and 17, 1936, the reports of the meetings and the discussions that took place has been published, accompanied by a list of the papers presented, grouped by subject matter and a list of books of interest to open hearth men The list below gives the Open Hearth Conference meetings in chronological order and the symbols used to designate them in the index SYMBOL MEETINGS P25 Pittsburgh, April 15 and 16, 1925 C125 Cleveland, Oct 13 to 15, 1925 Ch26 Chicago, April 12 and 13, 1926 P26 Pittsburgh, October, 1926 B27 Buffalo, May 3 to 5, 1927 D27 Detroit, Nov 2 and 3, 1927 Y28 Youngstown, May 3 and 4, 1928 P28 Pittsburgh, Nov 15 and 16, 1928 C129 Cleveland, May 16 and 17, 1929 Ch29 Chicago, Nov 5 and 6, 1929 B30 Buffalo, May 20 and 21, 1930 C130 Cleveland, Nov 20 and 21, 1930 Ch31 Chicago, May 12 and 13, 1931- D31 Detroit, Nov 24 and 25, 1931 P32 Pittsburgh, May 24 and 25, 1932 Ch33 Chicago, June 29 and 30, 1933 P34 Pittsburgh, June 28 and 29, 1934 C135 Cincinnati, April 11 and 12, 1935 D36 Detroit, April 16 and 17, 1936 The list of papers mentioned in the first paragraph above is reprinted on pages 428 to 431 The Index of the Open Hearth Proceedings may be purchased at A I M E headquarters, 29 W 39th St, New York

Jan 1, 1936

By Kenneth Cotingham

Many factors joined in reducing drilling activity in Ohio in 1942. Conservation Order M-68 was important, but other things, such as operators and members of drilling crews joining the armed services and going into war plants, had an important part. The reduction in number of completions was considerable. In 1941, the total of wells drilled was 1561 but in 1942 the total was 1008. The total initial daily open flow discovered by the 701 gas wells drilled in 1941 was 492,000 M cu. ft., whereas the open flow of the 471 gas wells completed in 1942 was 314,488 M cu. ft. The total initial daily production of the 333 oil wells drilled in 1941 was 10,300 bbl., and in 1942 the 181 oil wells had a total daily initial of 7570 bbl. The average daily initial per gas well therefore was somewhat less in 1942 when compared with the preceding year, but the initial per ail well increased about 36 per cent over 1941. General Activity The total depth of the 652 oil and gas wells drilled in 1942 was 1,597,000 ft. The most active county was Perry, where 63 oil wells were drilled, most of them in Clayton township. In Morgan County. where 43 gas wells were drilled, the greatest activity was in York and Marion townships. Medina County was third in number of wells drilled, although of the total of 33 gas wells in the county, 26 were in the new Hinckley township pool. The total initial open flow of these 26 wells was 39,202 M CU. ft., and was considerably larger than from any other single area. Muskingum was an active county, particularly Washington and Wayne townships, in each of which seven gas wells were drilled, and Blue Rock and Harrison townships, in each of which five gas wells were drilled.

Jan 1, 1943

By Kenneth Cotingham

Many factors joined in reducing drilling activity in Ohio in 1942. Conservation Order M-68 was important, but other things, such as operators and members of drilling crews joining the armed services and going into war plants, had an important part. The reduction in number of completions was considerable. In 1941, the total of wells drilled was 1561 but in 1942 the total was 1008. The total initial daily open flow discovered by the 701 gas wells drilled in 1941 was 492,000 M cu. ft., whereas the open flow of the 471 gas wells completed in 1942 was 314,488 M cu. ft. The total initial daily production of the 333 oil wells drilled in 1941 was 10,300 bbl., and in 1942 the 181 oil wells had a total daily initial of 7570 bbl. The average daily initial per gas well therefore was somewhat less in 1942 when compared with the preceding year, but the initial per ail well increased about 36 per cent over 1941. General Activity The total depth of the 652 oil and gas wells drilled in 1942 was 1,597,000 ft. The most active county was Perry, where 63 oil wells were drilled, most of them in Clayton township. In Morgan County. where 43 gas wells were drilled, the greatest activity was in York and Marion townships. Medina County was third in number of wells drilled, although of the total of 33 gas wells in the county, 26 were in the new Hinckley township pool. The total initial open flow of these 26 wells was 39,202 M CU. ft., and was considerably larger than from any other single area. Muskingum was an active county, particularly Washington and Wayne townships, in each of which seven gas wells were drilled, and Blue Rock and Harrison townships, in each of which five gas wells were drilled.

Jan 1, 1943

By R. H. Richards, A. E. Woodward

In Rittinger's Aufbereitungskunde of 1867 occurs (p. 195) the following table, which shows the rate of falling in water of fragments of minerals, of irregular shapes and of five different specific gravities: Diameter of particles in millimeters. 10 8 6 4 3 2 1 .5 Sp. Or. Velocity in meters per second. Auriferous silver, 16..9 .8 .7 .57 .5 .4 .29 .20 Galena,. ..7.5 .62 .55 .48 .39 54 .28 .20 .14 Pyrites,. ..5.0 .49 .43 .38 .30 .26 .22 .15 .10 Quartz,. ..2.6 -30 .27 24 .19 .17 .14 .10 .07 Coal,. ..1.3 .13 .12 .10 .08 .07 .06 .04 .03 With the purpose of extending this valuable table, to cover a larger number of minerals and sizes of each mineral, and of making it more easy of application in deciding upon a sieve-scale for any group of minerals, we have prepared the curves of velocity of fall of bodies in water shown in Plates I., XI., 111. and IV., using Rittinger's formula V= 2.44d(8 —1) where V= velocity in millimeters per second. " D = diameter of particles in meters. " 8 = specific gravity of the mineral. These curves embrace a large number of specific gravities, and for each specific gravity the relation of the diameter of the mineral particle to the velocity of its fall in water is given for all diameters and velocities used in practice. The second diagram is an enlargement of the lower left-hand corner of the first, the third bears the same relation to the second, and in like manner the fourth to the third. Plate I, therefore, covers the work of the coarsest jigging 2 inches in diameter; and under

Jan 1, 1890

By T. F. Witherbee

THE Fletcherville Furnace was built in 1864 and 1865, making its first blast from August until October of the latter year, when it was blown out to prevent its "bunging-up." Repairs were made in time to enable it to be blown in again December 12th, 1865, the blast ending October 7th, 1866. Total product 1921.15 tons iron, an average of 6.8.2.5 tons per day, from ores yielding 44.8 per cent. Consumption of charcoal 223.2 bushels per ton of iron. The furnace journal up to this time shows no record of furnace dimen¬sions, or temperature of the blast, but as near as can be ascertained, they were as follows, viz. Height of stack, 42 feet. Diameter of bosh, 11 feet. Angle of bosh, 7 1/2 inches to 12 inches rise, about 58°. Diameter of open tunnel head, 42 inches. Number of tuyeres 3; each 3 inches in diameter. Dam 15 inches high. Tuyeres 24 inches high. Tymp 22 1/2 inches high. Diameter of steam cylinder, 20 1/4 inches. Stroke 5 feet. Diameter of blast cylinder, 64 inches. The engine is direct-acting horizontal non-condensing. December 26th, 1.866, the furnace was again put in blast, having been considerably altered in the crucible; the height of stack, bosh, and tunnel head remaining as before. Six tuyeres were put in, three in each of the side arches. The hearth or crucible was rectangular in form, 3 feet wide x 32 feet long x 62 feet high. Inclination of bosh 58°. Height of tuyeres 26 inches ; nozzles 2 1/4 inches diameter. Temperature of blast estimated to be about 500°.

Jan 1, 1874

By Robert B. Sosman

ONE of the most neglected fields for physicochemical education as well as for research is that of high-temperature phenomena. Few universities or technical schools give instruction in the physical chemistry of substances at high temperatures. On the contrary such instruction is almost entirely confined to the region between the freezing and boiling points of water. This field should be extended to a much wider range of temperatures, both low and high. Such an extension is logical, sound, feasible, and practical.

Jan 1, 1943

By R. Dawson Hall

LONG regarded as nearly worked out, the anthracite region still shows promise of a hundred years of life, for means are being found to get bottom, top, pillar, and other coal that earlier generations disregarded as too expensive to mine. Rock drivages and, still more, machinery are making it possible to get such coal. Mechanical methods enable the owner of thin beds to mine these with profit, and the miner recognizes that he must permit the use of machinery or the inexorable laws of economics will deny him opportunity to work. E. L. Dana, Jr., well outlines this situation, which in the past year became definitely established. Stripping also is recovering, safely and inexpensively, coal that past generations regarded as too hazardous and costly for mining.

Jan 1, 1935

By C. W. Hall

MINE executives, as a rule, have always been willing to adopt new ideas of operation, or to listen to proposals which might increase the effectiveness of their enterprise, more especially so if they could be shown how definite results might be attained by introducing any conception suggested. In these days of high wages, high cost of supplies, and high taxes, operators are even more inclined to accord consideration to innovations or improvements, and many go so far as to employ men to conduct special investigations and make studies for the purpose of advancing production. Where a man is brought into an organization to do work of an efficiency nature, it often creates resentment among the operative heads because of having their work directly scrutinized, or investigated, and there is a tendency, if not actually to obstruct, to fa.il to cooperate; in which case the investigator is handi-

Jan 1, 1925