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For the use of future students the following notes on the times of completion of various railroads and canals supplying transportation to coal fields are set down. These dates are widely scattered and sometimes difficult to find. A statement showing the mileage of railroad building from 1830 to 1879 by each railroad in the United States is given in the 10th U. S. Census, 1880, vol. 4, pp. 318-365. [Date of Opening Various Bituminous Districts by Railroad Transportation1 Blossburg, Pa. district in1840 Georges Creek, Md. district in1842 Broadtop, Pa. district in1856 Clearfield, Pa. district in1866 Meyersdale, Pa. district in1872 C. & 0., W. Va. district in1873 Elk Garden, W. Va. district in1881 Pocahontas, Va. & W. Va. district in1883 Beech Creek, Pa. district in1884 Hocking Valley, 0. district in 1869.-by Canal 1840] See also Paullin's Atlas of the Historical Geography of the U. S., published by the Carnegie Institution of Washington, 1932, for small-scale maps showing railroad development by decades. [OHIO CANALS Date Date CompletedName of CanalFromToAbandoned 1827, July 4Akron Cleveland 1827, Nov. 28Cincinnati Middleton 1828, Dec. 31 Cincinnati Sandusky 1830, July 10 Cleveland Newark 1832, Dec. 31 Akron Portsmouth 1838Penna. & Ohio Akron Pa. Canals 1853 north of Pgh. 1840, Sept. Hocking Valley Columbus Nelsonville 1844 Sandusky Dayton 1846 Sandy & Beaver Bolivar Smith's Ferry 1852 1846 Cincinnati Springfield]

Jan 1, 1942

By Klaus W. John

The geologic factor of greatest significance in rock mechanics and rock engineering is considered to be the geologic structure represented by joints, faults, and other planes of weakness. This geologic structure differentiates between the rock element and the rock system composed of these elements. Only during the last decade has the difference of the technological properties of element and system been recognized but this appears to be more in theory than in engineering practice. If rock mechanics is to achieve real significance in engineering practice, it has to provide methods of analysis which are realistic compromises between the best representation of the actual conditions and pragmatic engineering. The rock mechanics practitioner has to face the fact that many geological engineering and rock mechanics problems may be too complex to allow rigorous analysis but at the same time are deemed satisfactory for the construction of major structures. Ultimately, the geotechnical engineer or the engineering geologist has to express the effect of geologic factors in quantitative, even if approximate, terms and provide numerical data on strength and deformability of rock systems to be utilized in construction. Qualitative evaluations, quantitative descriptions of geologic features as such, and comparisons of specific test results are always of interest but may not suffice as basis for engineering decisions and designs. The present efforts of the rock mechanics group at the Karlsruhe University, Federal Republic of Germany, are based on a systematic combination of geomechanical models and numerical analyses based on the finite element approach. This group considers that at the present stage

Jan 1, 1970

By David Cole

DAVID COLE, EL PASO, TEXAS (communication to the Secretary*).-I have read with great interest Dr. Gahl's painstaking paper giving us the details of development of flotation at Inspiration, and it seems to me that he has covered the ground so completely that there is little to discuss or criticize in connection with his subject. While it was in operation, the test mill in which the campaign was carried on was the Mecca of mill men and metallurgists. There was much to interest students of milling methods in addition to the flotation experiments, and readers of Dr. Gahl's paper will miss the information they hoped to get when the "pilot" mill results were. finally compiled, and I hope that the following remarks outlining from a distance some of the things that happened there will bring forth the rest of the story of the performances recorded in these important experiments. Prior to the use of flotation methods in concentration it had long been recognized that the "unavoidable" losses of sulphides were in the slime which is inevitably produced in the grinding operations required to free the minerals to be separated. Classifying the feed prior to its final stage of treatment had long been in style in milling. This assisted the sand-handling machines and resulted in lowering the tailings made by them, but at the expense of the slime-handling department; and while little was expected of the latter, the wisdom of complicating the process by hydraulic classification was being seriously questioned. Indeed, at the

Jan 10, 1916

By E. H. Barton

The necessity, on the Pacific Coast and throughout the semiarid regions in particular, of the conservation of waters for agricultural, industrial and mining purposes has forced itself upon the minds of those directly or indirectly interested in these industries. To meet the requirements of the case, storage must be provided for the flood-waters so abundant during the rainy season in order to insure a constant and unfailing supply during the summer months. Such storage can only be obtained, in the greater number of instances, by the erection of reservoir-walls of great height. The feasibility of employing earth or timber in the construction of such high dams is questionable, especially when (as is often the case) they must be placed in torrential streams. The experience of recent years with masonry dams, throughout this and foreign countries, has demonstrated that such dams, when intelligently and correctly designed and properly constructed, will meet the requirements of larger storage by means of increased height. The failures of masonry dams have been few; only two of any consequence being on record, namely, that of the Puentes dam, in Spain, in 1802, and that of the Habra dam, in Algiers, in 1810.* On the other hand, the failures of wooden and earthern dams are innumerable. The following are some of the most important structures constructed in recent years. The list is taken from Mr. Wegmann's book, just cited: The Furens, Zola, Ternay, Ban and Verdon dams, in France; the Nizar, Lozoya, Villar and the two Hizar dams,

Jan 1, 1900

AS we contemplate the bestowal of the John Fritz medal year after year on men of wide-world dis-tinction in the various fields of engineering, men who in one way or another have given impulse and direction to the progress of mankind, the question becomes inter-esting as to what manner of man was John Fritz and what were the qualities that singled out his name to be so conspicuously associated with the world's great scientific and industrial achievements. If, as Lowell said, it is the duty of the nation to pro-duce great men, our country surely rose to her oppor-tunity when she guided and guarded the career of John Fritz. Starting life as a blacksmith with no advantages of education, without influential friends or the favor-ing accidents of fortune, he advanced steadily in use-fulness, power and respect of his fellowmen until by common consent he occupied the first place in the domain of the steel industry of this, country. The numerous honorary scientific memberships conferred upon him in this country and abroad attest the esteem in which he is held by his fellow engineers. Twenty years after his retirement from active business at the age of seventy, he lived to enjoy, as few men have been permitted to do, the fame and the friendships which he had so amply earned. His sterner qualities of industry, integrity and sterling character were re-lieved by unfailing human sympathy, humor and spon-taneous good-will toward his fellowmen. To all who

Jan 3, 1928

By Leonard Waldo

The recent and rapid development of the physics of engineering materials at temperatures as low as that of liquid air and as high as that of the electric are, has drawn renewed attention to the absence of tables, properly printed and spaced, for the convenient and accurate translation of temperature from centigrade to Fahrenheit scales and vice versa. It is to be noted that the Fahrenheit scale is the almost universal usage in foundries and shops in the United States, though the laboratories of the same works employ the centigrade notation. The growing use of the electric furnace in Germany and France calls for much American citation all in centigrade high temperatures, and while the arithmetical calculation is simple, it becomes burdensome when often repeated. I have been surprised at the numerous reprints of Table I. from centigrade to Fahrenheit degrees, first privately printed for personal use, which have been made by works, blue-prints, text-books, and technical journals, and I hope that Table II., from Fahrenheit to centigrade degrees, will be equally useful. For mental calculation the easiest rule to convert centigrade into Fahrenheit is to add 32° to twice the centigrade reading less one-tenth of this product: Thus 1000' C. = 2000" — 200" + 32" = 1832" F., and to convert Fahrenheit to centigrade, subtract 32" from the Fahrenheit reading, multiply by 10 and divide by 2 and 9 successively : Thus 1000° F. = 1000° — 32° = 968° X 10 = 9680° - 2 = 4840° - 9 = 537.77° C. Another and often very convenient method is by 'use of a graphic construction as follows :

Jan 1, 1913

By Wells A. Hutchins

Water laws important to the mining industry are those which govern or affect the right to use water, to dispose of water after using it in mining or milling, and to discharge waste material into water-courses. They include statutes and court decisions having general applicability, as well as others that pertain specifically to mining. THE INDUSTRY'S CONTRIBUTION TO WESTERN WATER LAW Despite sharp differences of opinion, the water law the Spaniards brought to the Southwest appears to have included some form of appropriation of water. The Mormons, who settled in Utah in the mid-nineteenth century, also developed a system of appropriative water titles. But by far the most profound impact on western water law was made by the gold- seekers who flocked to the Sierra Nevada foothills of California after the discovery of gold in 1848. Much of the gold was extracted from the ground by hydraulic or placer mining, and so the-miners' rights to the use of water became fundamentally important. Since there was no organized government in the foothills and no laws other than those made by the miners, they helped themselves to the land, the gold, and the water needed to work their claims.' They established and enforced regulations governing the acquirement and holding of mining claims and their rights to the water they needed.'In 1879 Justice Field, former Chief Justice of the California Supreme Court, spoke for the U. S. Supreme Court in saying that the miners were "emphatically the law-makers, as respects mining, upon the public lands in the State.""

Jan 2, 1960

By George E. Beavers

Under the title used for this paper, the converter practice of the Tennessee Copper Co. is described in the TRansactions of the Institute.l That article contains the following statement: "The limit in capacity of the Peirce-Smith converter in terms of concentrate has not been reached but approximately as high as one ton of concentrate has been handled for each ton of liquid matte charged and good working conditions have been maintained." It is not the intention of the writer to review the conditions leading up to the introduction of a Peirce-Smith converter at Copperhill, but, instead, to offer later data to show how satisfactory the installation has been. Converter Campaign, June 15, 1930 to August 23, 1931 Blowing time (converter days)............... 349.90 Number of blows........................... 427.00 Tons matte charged........................ 38,335.00 Copper assay of matte, per cent.............. 13.67 Tons blister copper made.................... 9,246.00 Time to blow one ton of copper, minutes...... 54.50 Air used per minute, cu. ft................... 12,500.00 Blast pressure, lb........................... 12.80 Air per ton copper, cu. ft.................... 681,330.00 Air per ton iron, cu. ft....................... 199,040.00 Tons flux used............................. 11,845.00 Tons flux per ton matte..................... 0.31 Tons flux per ton copper.................... 1.28 Tons flux per ton iron....................... 0.37 Tons concentrate treated.................... 28,960.00 Copper assay of concentrate, per cent......... 17.13 Tons concentrate per ton matte.............. 0.76 Tons material charged per converter day...... 235.70

Jan 1, 1934

The failure of finely-divided sulfide particles to respond to flotation has resulted in a significant loss of our natural resources. As mentioned by Professor Arbiter, the overall recovery of copper from porphyry copper ores is generally between 80 and 85 percent. The recovery of copper sulfides from these ores is about 90 percent, the difference in these recoveries being due to failure of oxide copper minerals to respond to flotation. The 10-percent loss of sulfide copper has not been studied. Losses are known to be in the fractions finer than 74 microns, but the sizes that are not responding to flotation have not been established. In the case of molybdenite, however, it is known that particles finer than about five microns are not recovered. Work in other systems, notably the hematite-quartz system, has shown that good flotation of very fine particles from natural ores is possible (1, 2). The size distribution of one ore that was researched is given in Table 1, and as shown, approximately 50 percent of the ore was finer than 10 microns. Flotation experiments were conducted with this ore, which contained 45 percent iron, utilizing octyl hydroxamate as collector and without any desliming (1). The results of these experiments are presented in Table 2. From the standpoint of mechanisms of collector adsorption, similarities exist between those occurring in the hydroxamate-hematite system and many xanthate-sulfide systems. .This is, multilayers of ferric hydroxamate are present on hematite under flotation conditions (1,3).

Jan 1, 1979

By hydrometamorphism is meant the alteration of rocks, ores and minerals by atmospheric waters. In its broadest sense, it includes the varied processes of weathering, oxidation, hydration, the leaching of rocks and ores, and the solution, migration and enrichment of metals. Rain water, as it strikes the earth, is practically pure water, except for small quantities of dissolved atmospheric gases; upon coming in contact with ore minerals, especially sulphides, however, it is transformed into solutions of great chemical activity, which attack, transform and rearrange the minerals of ore- bodies, and so effect enrichments of the greatest economic importance. Primary deposits so low in grade as to be without commercial value are frequently thus transformed into deposits of commercial importance. It is necessary in the examination of any orebody, therefore, to determine whether the valuable ore is of primary or of secondary origin; if primary, its value may be expected to continue indefinitely in depth to the zone of primary impoverishment; if secondary, the ore deposition is known to be controlled by surface agencies, and the valuable ore may be expected to continue to such depths only as have been reached by surface waters. The decomposition and weathering of rocks, unlike the changes undergone by orebodies, are accomplished by water carrying as dissolved constituents chiefly atmospheric oxygen and carbon dioxide, together with vegetable acids. The chemical changes wrought are principally hydration, oxidation and the formation of carbonates. The tendency is toward the solution of the more easily dissolved minerals, which is attended by the formation and a surface concentration of the more resistant minerals,

Jan 1, 1932

Department of Conservation and Development, State of North Carolina, Raleigh, N C H J Bryson, State Geologist. The latest list of publications will be sent upon request. Of the many Bulletins, Economic Papers, Circulars and Volumes issued by the Department of Conservation and Development, the following are available and relate to mining and geology of the state ? Bulletin 18, Bibliography of North Carolina geology, mineralogy and geography (1909), 50 cents, 21, The Gold Hill mining district (1910), 15 cents, 22, Report on Cid mining district (1911), 15 cents, cloth 75 cents, 25, Zircon, monazite and other minerals, 15 cents, cloth, 75 cents, 28, Limestones and marls, 15 cents, 29, Kaolins of North Carolina, 50 cents, 31, Deposits of brown iron ore, 50 cents, 32, Magnetic iron ores, 15 cents, 33, The Deep River coal field, 50 cents, 37, Pyrophyllite deposits, 35 cents A series of the Economic Papers review the mining industry in North Carolina for the years cited Those now available are Economic Paper 23 (1908-1909-1910), 10 cents, cloth, 50 cents, 49 (1913-1917), 20 cents, 55 (1918-1923), 25 cents, 60 (1924¬1925), 15 cents, 63 (1927-1928), 25 cents. Other available Economic Papers on geology and mining are No 3, Talc and pyrophyllite deposits (1900), 25 cents; 58, Oil prospecting well near Havelock (1927), 5 cents, 59, Oil-bearing shales of Deep River Valley (1927), 10 cents Available volumes on geology. Vol 1, Corundum and the basic magnesian rocks (1905), 35 cents, cloth, $150, 5, The Cretaceous formations of North Carolina (1923), cloth $1 75

Jan 1, 1933

By Charles P. Williams

DURING the fall of the year 1873, attention was redirected to the occurrence of lead ores in Southwestern Arkansas (chiefly in Sevier County), and somewhat extensive explorations of the deposits have since been made in the hope of finding the ores sufficiently argentiferous to be profitably worked. How far the expectations have been realized I am not authentically advised, but samples of the galena ore, yielding 62.09 per cent. of lead, gave on assay at the rate of 15 3-10 ounces of silver to the ton of ore. This was the highest result obtained by myself, though I am informed that higher yields have been obtained by others. Among the samples of ores from this locality, forwarded to me in January last, was one specimen which I at once recognized as stibnite, and, on notification, other specimens of the same from Sevier County were forwarded me. The first specimen of the several received contained 11.51 per cent. of gangue, 57.62 per cent. antimony, 4.57 of bismuth, with small amounts of arsenic and iron. The latest result from a portion of another hand specimen I append in full, with duplicate estimations of the arsenic, bismuth, and gangue. The analyses were all conducted by Mr. C. R. Winters, under my direction, and in the case of those given below the ore was separated as closely as possible from the gangue before analysis. The results are for the mineral freed from hygroscopic moisture, and are as follows:

Jan 1, 1875

By R. V. Whetsel, V. R. Garfias

THE present study is intended as a preliminary statistical survey of the world's production of petroleum substitutes. The information presented is admittedly deficient. It is believed, however, that the increasing importance of these substitutes, particularly with Europe at war, justifies its presentation at this time, if for no other [ ] reason than to encourage enlightened pertinent discussion. The world's production in 1939 of petroleum substitutes-of which approximately 97 per cent are direct substitutes for motor fuels-is tentatively estimated at 108,000,000 bbl., or equivalent to the combined output of crude oil in 1939 of Rumania, Mexico and Colombia. With few exceptions, these figures of production represent also actual figures of consumption. The United States, owing mainly to its output of natural gasoline, leads all countries in the production of these products, with about 53 per cent of the total. In European countries, particularly Germany, the imminence of war in 1939 forced an increase in production and improvement of methods of manufacturing motor fuels, largely from coal, with the result that this country produced in that year over 20,000,000 bbl. of substitutes. Since the beginning of hostilities, substitutes have offered more and more the means of meeting the unfavorable balance between supply and demand in European [ ] countries; the increase in production of these products being at least in part offset by the systematic bombing of synthetic plants and oil storage. The source materials and the resulting substitutes are listed in Table I. The following are the approximate gross heat equivalents of some substitutes to barrels of gasoline:

Jan 1, 1941

By Andrew S. McCreath

THE manufacture of pig iron for conversion into steel by the Bessemer and open-hearth processes, is now one of the most important industries of the United States. It is necessary that iron intended for this purpose should be very pure, and especially must it be comparatively free from phosphorus. Great care must therefore he exercised in the selection of proper ores, flux, and fuel. Only such ores as are practically free from phosphorus can be used, and pure fuel is as much a necessity as pure ores; though hitherto iron men have paid comparatively little attention to this point. During the course of my work as chemist for the Second Geological Survey of Pennsylvania, I had occasion to examine some of the bituminous coals of the State for phosphorus, and the results obtained are so interesting that I venture to present them to the notice of the members of the Institute. The coals are arranged in geological order according to the different beds, and the table shows the percentage of phosphorus in the coal and also in the coke. The greatest number of specimens have been selected from the Pittsburgh bed, because it is the principal coal-bed of Southwestern Pennsylvania, and most of the mineral fuel which is mined along the Youghiogheny and Monongahela rivers, to be used in the coke ovens of the Connellsville region and in the blast furnaces and mills of Pittsburgh and its vicinity, and to be shipped to Western and Southern markets, comes from this bed. It will be noticed that many of the specimens examined contain

Jan 1, 1880

By Andrew S. McCreath

The manufacture of pig iron for conversion into steel by the Bessemer and open-hearth processes, is now one of the most important industries of the United States. It is necessary that iron intended for this purpose should be very pure, and especially must it be comparatively free from phosphorus. Great care must therefore he exercised in the selection of proper ores, flux, and fuel. Only such ores as are practically free from phosphorus can be used, and pure fuel is as much a necessity as pure ores; though hitherto iron men have paid comparatively little attention to this point. During the course of my work as chemist for the Second Geological Survey of Pennsylvania, I' had occasion to examine some of the bituminous coals of the State fix phosphorus, and the results obtained are so interesting that I venture to present them to the notice of the members of the Institute. The coals are arranged in geological order according to the different beds, and the table shows the percentage of phosphorus in the coal and also in the coke. The greatest number of specimens have been selected from the Pittsburgh bed, because it is the principal coal-bed of Southwestern Pennsylvania, and most of the mineral fuel which is mined along the Youghiogheny and Monongahela rivers, to be used in the coke ovens of the Connellsville region and in the blast furnaces and mills of Pittsburgh and its vicinity, and to be shipped to Western and Southern markets, comes from this bed. It will be noticed that many of the specimens examined contain

Jan 1, 1880

Steps were taken for a permanent organization of the scientific and technical employees of the Government at their mass meeting on May 8. This was the result of an informal meeting on Apr. 23 of thirty representative Government scientists and technical men who organized the preliminary committee and called the mass meeting. This subject has been widely discussed during the last year and was brought acutely to the fore by the work of the Joint Congressional Reclassification Commission, because that Commission has stated that it wished to deal with employees only through organizations. Rodney H. True of the Department of Agriculture was Acting Chairman. He pointed out that the principal advantages that were expected to be derived from such an organization were: (1) Improvement of conditions and facilities for more effective scientific and technical work; (2) adequate presentation of the needs. and results of such work to the public and to legislative and administrative officers; (3) -greater freedom in both official and non-official activities; (4) just and reasonable salaries based on service performed and the economic and social conditions which prevail; (5) greater public recognition of the aims and purposes of research; (6) advancement of science and technology as an essential element of national life. Three plans of organization were offered to the meeting, which covered the fundamental principles which could be utilized by these Government employees. The first plan would have permitted the new organization to work only through existing scientific organizations. This is the plan that scientific and technical Government employees in England have adopted and an outline of the English plan was read to the meeting.

Jan 6, 1919

AS I told you before in the treatise on ores, once these are found (whether they are ores of metals or semiminerals) it is necessary to assay them in order to know what is in them, since the judgment of the sight is not sufficient for recognizing the quantity or even what substance they contain. For this reason, it is necessary to come to assaying and, with the knowledge of experience, to weigh their virtues and to proceed with the work or withdraw from it and its expense; and also through knowledge to make provision for their defects if some evilness harms the ores. For if you should have need of a thing that would help them and should not find it, all that you have done would be lost; and, on the other hand, if you should find that the ores are abundant and rich and easy to smelt, you take courage to continue without respect for anything. Therefore, in the following book I shall tell you first in general how the assay of all the metals should be made. I shall enlarge in particular on silver more than on any of the others since it is more important. Then I shall tell you how the ores should be prepared for smelting and also how blast furnaces and other furnaces for smelting such ores should be constructed, and finally how all elemental mixtures of metals are to be separated one from the other with the ability and power of art, and how they are reduced to their final perfection and fineness according to their species.

Jan 1, 1942

National Society of Professional Engineers has thrown its full sup- port behind pending legislation to appropriate $500 million for national conversion efforts that would provide employment opportunities for engineers, scientists, and technicians who are currently unemployed because of the decline in defense and aerospace programs. Known as the Davis-Giaimo bill, the proposed legislation would raise total Federal investment in science and technology to an adequate annual spending level and keep it proportionally equal to the growth in the GNP. If passed, the bill would increase and maintain Federal obligations for civilian-oriented research and development activities to a parity level with similar obligations for defense research development. U. S. Bureau of Mines has cataloged and placed on open file an inventory of U.S. coal deposits which can be economically strip mined at today's production costs. The costs include charges for reclaiming the mined land as required by 21 states. The report claims that some 46 billion tons of bituminous coal and lignite can be strip mined under present economic conditions, and that 32 billion tons of the total is classified as having less than 1% S. The report reviews strippable coal deposits by state, by county, by coal seam, by coal-seam thickness and by sulfur content. The report also gives an up-to-date summary of state laws on surface mine reclamation. Open-file copies of "Strippable Reserves of Bituminous Coal and Lignite in the U.S." may be consulted in Washington, D.C., at the Department of the Interior library and at U.S. Bureau of Mines offices in Pittsburgh, Denver, San Francisco. Dallas. Spokane, and Douglas Island, Juneau. Alaska.

Jan 1, 1971

By H. P. Reid

PORTLAND cement is manufactured under either of two general proc-esses, the wet or the dry. The raw materials in general consist of limestone, shells, marl, cement rock, clay, shale, blast-furnace slag, etc., so proportioned that when calcined the desired composition will be obtained. In the wet process the combined raw materials are ground to extreme fineness in the presence of water, to a resulting slurry of from 30 to 50 per cent moisture content. The moisture of the slurry may be reduced by thickening or filtering processes for feed to the cement kiln or the slurry may be fed to the kiln with its full percentage of water. The dry process differs from the wet in that the surface moisture of the raw materials is removed prior to grinding. For the drying of these materials heat is required and in most cases is produced by burning of raw fuel either on grates or stokers before the dryers or in suspension in the form of pulverized coal, oil or gaseous fuel. The power required for making the cement is sometimes purchased from outside sources; sometimes it is generated from the heat in the waste gases leaving the cement kilns, or generated at the plants direct from raw fuel. We have, then, as the possible requirements of fuel in the cement industry: (1) fuel for power generation, (2) fuel for drying raw materials, including coal before pulverizing, and (3) fuel for burning the raw materials to cement clinker. There is no essential difference in quality required in fuel for burning the materials by the wet and dry processes.

Jan 1, 1932

By Henry Howe

(New York Meeting, February, 1913.) THE transformation which steel undergoes in glow cooling, from the condition of austenite when above the transformation range into that of pearlite plus either ferrite or cementite below that range, is subject to great lag. This transformation is essentially the pearlitizing of the austenite. Indeed the hardening of steel is due to this lag, which is made so great by extremely rapid cooling that a very large part of the transformation itself is restrained, so that the rapid cooling catches the metal in an only partly transformed state, that of martensite, and under favorable conditions even in an almost wholly untransformed state, as in the cases of Maurer's austenitic manganese steel. Hadfield's austenitic manganese steel, 25 per cent. nickel steel, and other austenitic alloy steels, are austenitic even after slow cooling. It has long been known that this- lag increases (1) with the rapidity of cooling, (2) with the presence of certain retarding elements, notably manganese and nickel, and (3) with the temperature from which cooling starts. The present inquiry touches the last. of these influences, but incidentally it throws light on the first also. This influence of higher heating in increasing lag manifests itself in different ways which, though they may at first seem unrelated, are in fact but different, aspects of one and the same thing. Thus, among heatings to different high temperatures, all of them above the transformation range, the higher the temperature to which the steel is heated (1) the lower is the temperature it which the transformation occurs in cooling slowly down, (2) the shorter is the time occupied in the actual cooling from above the transformation range to the room temperature under given external conditions, whether of slow or

Jan 3, 1913