SECTION II: PHYSICAL GEOGRAPHY AND STATISTICS (cont.)
Part 21. Mineral Resources
In 1619 the erection of "works" for smelting the ores of iron was begun at Falling Creek, near Kamestown, Va., and iron appears to have been made in 1620; but the enterprise was stopped by a general massacre of the settlers in that region. In 1643 the business of smelting and manufacturing iron was again begun at Lynn, Mass., where it was successfully carried on, at least up to 1671, furnishing most of the iron used in the colony. From the middle of the 17th century the smelting of this metal began to be of importance in the vicinity of Massachusetts Bay, and by the close of the century there had been a large number of iron-works established in that colony, which, for a century after its settlement, was the chief seat of the iron manufacture in America, the bog ores, taken from the bottoms of the ponds, being chiefly employed. Early in the 18th century industry began to extend itself over New England, and into New York and New Jersey, the German bloomery or forge being employed for reducing the ore directly to bar iron, and by the middle of that century it had taken a pretty firm hold in the Atlantic States. About 1789 there were fourteen furnaces and thirty-four forges in operation in Pennsylvania. Before the separation of the colonies from the mother country took place the manufacture of iron had been extended through all of them, with the possible exception of Georgia. As early as 1718 iron (both pig and bar) began to be sent to Great Britain, the only country to which the export was permitted, the annual amount between 1730 and 1775 varying ordinarily between 2000 and 3000 tons, but in one year (1771) rising to between 7000 and 8000 tons.
So far as known, the first metal, other than iron, mined by the whites within the territory of the United States was copper. The first company began work about 1709, at Simsbury, Conn. The ore obtained there and in New Jersey seems to have been mostly shipped to England. A few years later attempts were made to work mines of lead and cobalt in Connecticut and Massachusetts, but none of these enterprises seem to have been conducted with much vigor or to have met with any success. The first metal, other than iron, mined and smelted on any scale of importance was lead. The ore of this metal-galena-occurring in considerable quantity, and in many localities, on or near the Mississippi, and being easily smelted by the roughest methods, was made use of at an early date. While this region-then called Louisiana- was in possession of the Spanish, some mines were opened and worked, although in a very rude manner, the ore being taken out from mere pits and smelted on log-heaps. In 1774 Julien Dubuque began operations in the region of the upper Mississippi, at the place where is now the flourishing city which bears his name, but no real development of the mining interest took place in that region until half a century later.
The first mining excitement of the United States dates back to the discovery of gold by the whites in the southern States, along the eastern border of the Appalachian range, in Virginia, and in North and South Carolina. The existence of gold in that region had been long known to the aboriginal inhabitants, but no attention was paid to this by the whites, until about the beginning of the present century, when nuggets were found, one of which weighed 28 lb. From 1824 the search for gold continued, and by 1829 the business had become important, and was attended with no little excitement. In 1833 and 1834 the amount annually obtained had risen to fully a million of dollars. A rapid development of the lead mines of the West, both in Missouri and on the upper Mississippi in the region where Iowa, Wisconsin, and Illinois adjoin one another, took place during the first quarter of the present century, and as early as 1826 or 1827 the amount of this metal obtained had risen to nearly 10,000 tons a year. By this time the make of iron had also become important, the production for 1828 being estimated at 130,000 tons.
In 1820 the first cargo of anthracite coal was shipped to Philadelphia. From 1830 the increase in the production was very rapid, and in 1841 the annual shipments from the Pennsylvania anthracite region had nearly reached 1,000,000 tons, the output of iron at that time being estimated at about 300,000 tons. The development of the coal and iron interests, and the increasing importance of the gold product of the Appalachian auriferous belt, and also of the lead product of the Mississippi valley, led to a more general and decided interest in geology and mining; and about 1830 geological surveys of several of the Atlantic Sates were begun, and more systematic explorations for the ores of the metals, as well as for coal, were carried on over all parts of the country then open to settlement. An important step was taken in 1844, when a cession of the region on the south shore of Lake Superior was obtained from the Chippeway Indians. Here explorations for copper immediately commenced, and for the first time in the United States the business of mining for the metals began to be developed on an extensive scale, with suitable appliances, and with financial success. An event of still greater importance took place almost immediately after the value of the cooper region in question had been fully ascertained. This was the demonstration of the fact that gold existed in large quantities along the western slope of the Sierra Nevada of California, a region which had just come into the possession of the United States. The discovery led to extraordinary excitement throughout the older States, and to an immigration from all parts of the world on an unprecedented scale. The production of this precious metal rose almost at once to figures far surpassing anything definitely known in history. In five years from the discovery of gold at Coloma on the American river, the yield form the auriferous belt of the Sierra Nevada had risen to an amount estimated at between sixty-five and seventy million of dollars a year, or five times as much as the total production of this metal throughout the world at the beginning of the century. This rapid development led to a great mining excitement in the eastern States, as a result of which new veins and deposits of various metals were discovered, and many which had been previously worked to a limited extent and then abandoned were again taken up. This excitement was at its height in 1852 and 1853, but soon slackened as it began to be shown by the results of actual working that, while "indications" of the valuable ores of the metals are very abundant in the Appalachian belt, the localities where these ores occur in sufficient abundance to be profitably worked are comparatively few.
The following details show the development of the mineral resources of the country at the middle of the present century. In 1850 the shipments of anthracite amounted to nearly 3,500,000 tons; those of Cumberland or semi-bituminous coal were about 200,000 tons. The yearly production of pig iron had risen to between 500,000 and 600,000 tons. The annual yield of gold in the Appalachian belt that fallen off to about $500,000 in value, that of California had risen to $36,000,000, and was rapidly approaching the epoch of its culmination (1851-1853). No silver was obtained in the country, except what was separated form the native gold, that mined in California containing usually from 8 to 10 per cent. of the less valuable metal. The ore of mercury had been discovered in California before the epoch of the gold excitement, and at New Almaden, about 100 miles south of San Francisco, was being extensively and successfully worked, the yield of this metal in the year 1850-51 being nearly 2,000,000 lb. At this time the copper mines of Lake Superior were being successfully developed, and nearly 600 tons of metallic copper were produced in 1850. At many points in the Appalachian belt attempts had been made to work mines of copper and lead, but with no considerable success. About the middle of the century extensive works were erected at Newark for the manufacture of the oxide of zinc for paint; about 1100 tons were produced in 1852. The extent and value of the deposits of zinc ore in the Saucon valley, Pennsylvania, had also just become known in 1850. The lead production of the Missouri mines had for some years been nearly stationary, or had declined slightly from its former importance; while that of the upper Mississippi region had, in the years just previous to 1850, risen to from 20,000 to 25,000 tons a year, but was gradually declining, having in 1850 sunk to a little less than 18,000 tons.
Coal. Coal exists in the United States in large quantity in each of its important varieties,- hard coal, or anthracite; soft or bituminous coal; and lignite, or brown coal. Semi-bituminous coal, which stands midway between hard and soft coal, is also an article of importance, being especially well adapted for blacksmiths use, and also for ocean-going steamers. Geologically, the anthracite, semi-bituminous, and bituminous coals nearly all belongs to the same formation, the Carboniferous par excellence. All the coal of the Appalachian region and Central Valley is of this geological age, excepting the small field near Richmond, Va., and two in North Carolina, the Deep River and Dan River fields, which are of Mesozoic age. That of Richmond was the first coal-field worked in the United States; but it is no longer of any importance. The North Carolina Mesozoic areas have never been developed to any extent. All the Cordilleran coal and that at the eastern base of the Rocky Mountains is either tertiary or belongs to the very uppermost portion of the Cretaceous. Some of it is decidedly lignite, and is so called by the people who use it; but most of it, although of so recent geological age, is called coal, and, in point of fact, does not differ essentially from Palaezoic coal in external appearance. The area underlain by the Coal-measures in the United States is very large.
The areas of the various coal-fields are, in round numbers, as follows: - Rhode Island, 500 square miles; Appalachian, 59,000 Central (Illinois, Indiana, Kentucky), 47,000; Western (Missouri, Iowa, Kansas, Arkansas, Texas), 78,000; Michigan, 6700; total, 191,200. of these fields the Appalachian is, and is likely long to remain, by far the most valuable. Those of Rhode Island and Michigan are practically of very little importance. Different portions of the fields are of very different value, as respects quality and quantity of coal, and portions of them do not contain coal-beds of sufficient thickness or of good enough quality to be worked with profit.
The following table (VI.) shows the amount of coal produced in the several States and Territories (not including the local and colliery consumption), and the value at the mines in 1885:-
The amount consumed for local and colliery use would increase the total five or six per cent. including all the coal thus consumed, the figures for the four years ending 1885 stand as follows, the value at the mine being added for each year, except that for 1885 the value of the "commercial coal" only is given: - 1882, 92,219,454 tons, $146,632,581; 1883, 102,867,969 tons, $159,494,855; 1884, 106,906,295 tons, $143,768,578; 1885, 99,069,216 tons, $152,915,268.
The Appalachian coal-field does not occupy any portion of the State of New York, but extends from near its southern boundary south-west into Georgia and Alabama: - Pennsylvania, 12,302 square miles; Maryland, 550; Ohio, 10,000; West Virginia, 16,000; Virginia, 1000; Kentucky, 8983; Tennessee, 5100; Georgia, 170; Alabama 5530; total, 59,635 square miles.
Pennsylvania, to which State the anthracite of the country is practically limited, produces more than half the coal raised in the United States, and about one-eight of the total yield of the world, the increase during the past five years having been astonishingly rapid. Ohio stands next in importance among the States so situated as to have a portion of this field within their borders, - its yield, however, being only one-eight of that of Pennsylvania. Maryland produces about one-third as much as Ohio. The production of the remaining States over which the Appalachian field extends is small as compared with the extend of their areas underlain by coal. In Kentucky and Alabama, however, some progress has been made within the past few years. About three-quarters of the coal mined in the United States is from the Appalachian field. Next in importance to the Appalachian is the Central coal-field, from which Illinois draws its supplies of fuel. The yield of that State is somewhat less than a fifth of that of Pennsylvania, while Indiana produces about one-fifth as much as Illinois. The coal of the central field is decidedly inferior to that of the Appalachian, since it contains on the average considerably more ash and more water. the quality of the coal of the Western field is somewhat variable, but on the whole inferior to that of the Illinois field. The region over which it is spread is, however, not well supplied with forests; and hence the amount annually raised is considerable (nearly 4,000,000 tons for Iowa and 2,500,000 for Missouri). The southern extension of this field through Arkansas and Texas has, as yet, been very little explored or developed. The coal-producing areas of the Cordilleran region are all of comparatively small size, and no one of them is capable of furnishing a large supply for any considerable number of years; but taken together they are of great value, not only for local consumption, but for supplying the Mexican plateau. The Cordilleran coal (some call it lignite) is all newer than the carboniferous; and it is not known that there is any coal at all, either in the Rocky Mountains or farther west, in that portion of the geological series which is the palaeontological equivalent of the true "carboniferous." A large part of the Cordilleran coal has a geological position close upon the line between the Cretaceous and Tertiary. By some palaeontologist it is referred to the one, by some to the other. The quality of this newer coal is very variable; in some localities it is quite good, but in general it is decidedly inferior to the average coal of true Carboniferous age; some portions are distinctly lignitic in character.
While the amount of coal in the United States is large, it is not by any means so much larger than that of England as it has been always inferred to be from the simple consideration of the comparative dimensions of the areas over which cola is known to exist in the two countries. In the Central and Western fields the number of beds is small, and they are never of great thickness; not is it known how far the total area embraced within the limits usually assigned as that of these fields was really originally underlain continuously by coal-seams, or how much of these seams has been removed by erosion. It is only in regard to the anthracite fields that even an approximate statement of the total remaining available quantity of coal can be made. Mr. P. W. Sheafer, a mining engineer of long experience in that region, has made a statement that the anthracite fields originally contained about 25,000,000,000 tons of coal. Mr Ashburner, the assistant in charge of the State survey of the anthracite coal district, has stated that, up to 1st January 1883, the total production of that district had amounted to 509,333,695 tons. He also estimates that two-thirds of the coal actually attacked had been lost in the mining. Making allowance for increased consumption and other considerations, it would appear that 200 years must be taken as the maximum time during which the anthracite fields will hold out, while it is probable that they will be practically exhausted considerably earlier. As regards the quantity of available coal in any portion of the bituminous coal-fields of the county, the only estimate we have is that of Prof. Lesley, who (February 1886) estimates the amount of available coal in the Pittsburgh seam at 5,000,000,00 tons, but confesses that any exact calculation is impossible. If the consumption remains at the figure at which it stood in 1884 (11,000,00 tons) this quantity will last about 450 years.
Petroleum. The oil-producing districts of present or past importance are nearly all in Pennsylvania; but there are small productive areas in the adjacent portions of New York. (1) The Allegany district, including the Richburg and several small outlying pools in Allegany county, New York, has a productive area of 31 square miles, and up to January 1885 produced 15,000,00 barrels. (2) The Bradford district, embracing the oil-pools in central and northern MKean county, Pa., and southern Cattaraugus county, N.Y., has a productive area of 133 square miles, 121 of which are included in the Bradford field proper. The geological position of the oil-bearing strata is indicated by the fact that the uppermost oil-sand is, at Bradford, 1775 feet below the bottom of the lower member of the millstone grit, or Pottsvile conglomerate, which in western Pennsylvania is one of the most persistent and best-recognized geological horizons, and is there known as the Olean conglomerate. This district had up to January 1885 produced 109,000,000 barrels of oil. (3) The warren district lies in eastern Warren and north-eastern Forest counties, Pa.; it has an area of 35 square miles, and up to January 1885 had produced 12,000,000 barrels. The oils from different subdivisions of this district vary considerably in color and gravity, although generally spoken of as "amber oils." They come from "sands" (sand rocks) of varying geological horizons, from 1100 to 1850 feet below the Olean conglomerate. (4) The Venango district the scene of all the earlier oil developments-has an area of 65 square miles, and includes forty distinct and well-recognized oil-pools, the largest of which lies between Oil City on the south and Pleasantville on the north, and covers an area of 28 square miles. The production of this district up to January 1885 had been about 55,000,000 barrels. The oil of the Venango district comes from three principal sand beds, of which the uppermost one lies about 450 feet below the base of the Olean conglomerate. They are all contained within an interval of 350 feet. The oils are generally green, but frequently black, and sometimes amber. The pebbles of the sand rocks are water-worn, sometimes as large as hazel-nuts, loosely cemented together and bedded in fine sand; but the sands are not so regular or homogeneous as in the Bradford and Allegany fields; consequently, the risk of obtaining unproductive holes and variable wells has always been greater in the Venango than in the Bradford and Allegany districts. (5) The Butler district includes the oil-pools inButler and Clarion counties and in south-eastern Venango county. The area is 84 square miles, and up to January 1885 the production had been about 69,000,000 barrels. The oil here comes from the same group of sand rocks as in the Venango district. (6) The Beaver district includes the two principal oil-pools known as Slippery Rock and Smiths Ferry, having an area of about 16 square miles, with a production of 1,000,000 barrels up to January 1885. In both the oil-pools of the Beaver district heavy oil is obtained from the representative of the Pottsville conglomerate, and amber oil from the Berea grit, a member of the Sub-carboniferous series. The geological position of all the other oil-fields is considered by the geologists of the Pennsylvania Survey as Devonian. The total area of the productive oil areas is given by Messrs Carll and Ashburner at 369 square miles, and the general boundaries of the oil-regions of Pennsylvania are now regarded as established. That production is declining is shown by the following figures. In July 1883 the number of producing wells was 17,100, and the average daily product per well was 3.8 barrels; in 1884 the corresponding figures were 21,844 and 3.0, and in 1885 they were 22,524 and 2.5 Since July 1882, when the maximum average daily production for any one month was realized (105,102 barrels), there has been an irregular but steady decline. In 1884 the shipments of petroleum were more than 1,000,000 barrels in excess of the production. At the end of August 1884 the stock of oil on hand had reached its maximum 39,084,561 barrels; in September 1885 it had declined to 35,343,771 barrels. The price of petroleum had not, up to July 1885, been influenced by this condition of things, crude oil being at that time worth 92 _ cents a barrel, 13 _ cents less than the average price for 1884. the extraordinary fluctuations in the price of petroleum during 1880 to 1886 are shown by the following figures:-in 1880 it ranged from 124 3/8 to 80 5/8 cents per barrel for crude oil; in 1881 from 100 _ to 72; in 1882 from 135 to 49 1/4 ; in 1883 from 125 to 84 3/4 ; in 1884 from 114 _ to 51; in 1885 from 111 5/8 to 78; in 1886 from 92 _ to 59 _. These figures, however, have but little reference to changed conditions of production. The fluctuations are simply the results of a colossal system of gambling, the magnitude of which may be inferred from the statement that the "clearances" on the "consolidated stock and petroleum exchange" for 1886 amounted to about 2,275,000,000 barrels. The daily average exports of petroleum for that year are given at about 44,300 barrels. The tendency to lower prices in 1886 was due in part to the remarkable yield of the oil-wells at Baku, on the Caspian Sea, and in part to discoveries, supposed to be of importance, in Ohio.
Natural gas. The use of natural gas for illumination, and even for metallurgical purposes, has lately become a matter of importance. The existence of outflows or springs of gas in the region west of the Alleghany range has been long known, and the gas obtained from wells or bore-holes was used for illumination in Fredonia, N.Y., as early as 1821. One well after another was bored for this purpose at that place, until, in 1880, the supply had reached the amount of 110,000 cubic feet per month. The following figures, reported by T.P. Roberts, show the estimated value of the coal displaced by natural gas in the region where this source of that and light was in use for the years mentioned: -
Gas seems to be a general concomitant of the oil all through the petroleum region, but for a long time the outflow of gas from the oil-wells was looked upon as a nuisance. According to Mr. Ashburner, the amount of gas at present flowing from the explored sands of Pennsylvania is probably two or three times greater than is required to meet all present demands. The same authority gives an account of the development of the natural gas resources of Ohio. Their amount is not yet ascertained with any degree of certainty, but it seems likely to be large. All the gas comes from the Palaeozoic strata, from the Upper Coal-measures down to the Trenton limestone, - the most prolific gas-bearing rocks being the Berea grit in the Sub-Carboniferous and the Trenton limestone of Lower Silurian age. Natural gas has obtained in numerous localities in New York, but nowhere in considerable quantity except in the vicinity of the Allegany oil-district, in the county of that name. Portions of West Virginia, especially the Kanawha valley, give promise of being regions of large production.
Iron and Steel. The following table (VII.) will convey an idea of the condition of the iron industry at the date of the last census, and of the progress made during the ten preceding years: -
== TABLE ==
The "weight of products," as given above, includes the products of all the various processes or operations; hence there is evidently a certain amount of duplication (rolled iron, for instance, being mainly produced from pig). The following table (VIII.) gives the production in each branch of the steel and iron industries: -
The distribution of the iron industry is extremely irregular. West of the Mississippi, with the exception of the angle between that river and the Missouri adjacent to St Louis, the amount of iron made is very small. The percentage of total production in 1880 was distribution as follow: - Pennsylvania, 50; Ohio, 13; New York, 8; Illinois 6; New Jersey, 3; Wisconsin, W. Virginia, Michigan, and Massachusetts, each nearly 2; Missouri, Kentucky, and Maryland, between 1.5 and 2; Indiana and Tennessee, about 1; all the other States and Territories, an aggregate of about 4 per cent. New England now makes but little pig iron, and the South scarcely any rolled iron; the West has largely embarked in the manufacture of steel by the Bessemer process, while New York has not a single Bessemer establishment; New York manufactures chiefly from ore, and Pennsylvania from pig and scrap iron; Michigan is the leading producer of charcoal pig iron, and now makes no other kind; only five States make Bessemer steel; and two States, Pennsylvania and New Jersey, produce nearly all the crucible steel.
The census year 1880 was one of exceptional prosperity for the iron and steel industries of the country. The production of pig iron and of Bessemer steel ingots and rails since 1880 is shown in the following table (IX.), from the statistics collected by the American Iron and Steel Association: -
== TABLE ==
The total number of completed Bessemer steel works at the close of 1886 was 33, with 69 converters. Pennsylvania in that year made 59 percent. Of the ingots produced, Illinois 21, and other States 20. In the following table (X.) the amount of steel of all kinds produced is given (in tons) for the years stated:-
== TABLE ==
By Far the largest production of iron ore in the United States is from the rocks which lie below the Lower Sulirian the Azoic series of Foster and Whitney and the Archaean of Dana. In this formation the ore occurs in immense quantity in what may without exaggeration be called mountain masses, which in many cases exhibit all the evidences of an eruptive origin, as in the case of the iron Mountain of Missouri, or in some of the localities in the Marquette and Menominee regions of Lake Superior. At the first-mentioned locality the ore is intimately associated with an undoubted eruptive rock, with which it is intermingled in such a manner as to show that the two ore and rock- must have had one and the same origin. A similar condition of things is revealed on Lake Superior, where the ore occurs in repeated interlamination between sheets of unquestionably eruptive material. The ores thus occurring are haematite or specular ore and magnetite, with some hydrated oxide, or limonite, the result of the action of water on the previously formed haematite. They are in general extraordinarily free from deleterious ingredients, especially phosphorus and sulphur, although usually containing a small amount of silica. The purity of these ores is a strong indication of their origin differing from that of ordinary sedimentary deposits. Many of the analyses of Lake Superior ore show the presence of only a few hundredths of one per cent. of phosphorous. The most important district in which these ores occur is the south shore of Lake Superior, and the most important port of shipment is Marquette, a considerable amount being also shipped from Escanaba on Lake Michigan. From 1856 to 1886 the total shipments of iron ore from the region amounted to 31,030,160 tons. A district known as the Vermillion lake iron district, in which the ore has similar characters, and where the quantity is believed to be very large, has been recently opened in Minnesota, on the north shore of Lake Superior. The Iron Mountain region, a little less than a hundred miles south of Saint Louis, although small, is of considerable importance. A very large portion of the Lake Superior ores goes to the Appalachian coal-field to be smelted; and this was formerly the case with the Iron Mountain ore, but the latter is now used in nearer localities. There is a very important and apparently inexhaustible deposit in Lebanon county, Pennsylvania; the ore is chiefly magnetite, and its mode of occurrence in close connection with an eruptive rock is to the present writer strong, if not absolutely convincing, evidence of its igneous origin. There are important deposits of iron ore, on the eastern border of New York, especially in the Adirondacks, and along the Hudson River. The geological position in which a portion of these ores occurs is certainly the same as that of the ores of Lake Superior namely, the Azoic. That is the character of the Adirondack ores, which have long been and still are extensively worked. The localities are chiefly in Clinton, Essex, and Franklin counties. In the last-named county are the very extensive Chateau gay mines. The ores of this region are chiefly magnetite, but they often contain too much phosphorus to be used in the manufacture of steel. There are important occurrences of magnetic ore near New York city and also near the Hudson river, in Orange, Rockland, Putnam, and Columbia counties. Some of these ores are adapted to the manufacture of Bessemer steel. The mode of occurrence of the ore sin southern New York and northern New Jersey ores as unquestionably of sedimentary origin. This New Jersey district is not in a flourishing condition at present, since the ores, as a rule, are not adapted to the manufacture of Bessermen steel. Similar ores occur at many points, and often in large quantity, in the Azoic or crystalline belt of the Appalachian system, in the States lying farther south than New Jersey. In Mitchell county, North Carolina, is a deposit known as the Cranberry Bank, of which the quality is excellent, and the quantity s believed to be very great. Up to the present time, however, but little of this ore has been shipped. Next to the Azoic ores in importance, but decidedly inferior in quality, are those of the Clinton group, a member of the Upper Silurian series. The ore occurring in this geological position is known by various names, the most common ones being fossil or dyestone ore. It is a red haematite, not crystalline like the specular variety of the peroxide, but usually in a more or less granular or concretionary form, that of flattened grains resembling flax seed being a common mode of occurrence, whence the name "flax-seed ore." This deposit occurs at many points along the outcrop of the Clinton group all the way around from Wisconsin, though Canada and New York, into Pennsylvania, and down the eastern slope of the Appalachian range to Georgia, and is said to be the most extensive deposit of iron ore in the world yet discovered. The fossil ore, though large in quantity, contains too much phosphorus to be used for making steel in the ordinary method; but, being in places favorably situated with regard to fuel, and yielding as it does a satisfactory quality of cast iron, it is extensively mined at various points. Next to the Clinton ore in importance comes the brown haematite ore (limonite), which occurs in numerous localities, but of which the most extensive deposits are those occurring in the Lower Silurian limestones of the Appalachian system, and especially along the line of the Great Valley. Some of the ores are of excellent quality, notably those of Litchfield county, Connecticut, in the so-called Salisbury district. The iron made in charcoal furnaces in this region is considered as being of the highest value for articles in which strength and toughness are essential. Carbonate of iron, in the form of spathic iron, is of race occurrence. The argillaceous carbonates (clay ironstone) are also of comparatively little importance, although used to some extent, especially as mixed with other ores, in western Pennsylvania and Ohio. The coal-fields west of the Appalachians are very poorly supplied with iron ores. Blackband ore is also of somewhat rare and limited occurrence in the United States.
In spite of the abundance of iron ore in the United States and the existence of a heavy protective duty (75 cents per ton), a large quantity of ore is imported from abroad- chiefly from Spain, Elba, Algiers, and Cuba (1,039,433 tons valued at $1,912,437 in 1886). Almost all this was used in Pennsylvania, and chiefly in the manufacture of Bessemer pig iron and spiegeleisen. Up to 1884, at least, no pig iron suitable for the manufacture of Bessemer steel by any process now in use in the United States had ever been made south of the Potomac or south of Wheeling. Neither has iron suitable for crucible steel been made in the United States which can compete with that of Sweden.
The annexed table (XI.) published by Mr. Swank, shows the production of iron ore in tons in the leading ore-producing districts for the years 1884, 1885, and 1886;-
Gold and Silver. The washing of the high or tertiary gravels by the hydraulic process and the working of mines in the solid rock did not, on the whole, compensate for the diminished yield of the ordinary placer and river diggings, so that the produce of gold in California continued to fall off, and by 1860 had decreased to about half what it had been ten years before. discoveries in other Cordilleran territories, notably in Montana and Idaho, made up, however, in part for the deficiency of California, so that in 1860 the total amount of gold produced in the United States was estimated at not less than $45,000,000. In the latter part of the decade 1850-59 the Territories adjacent to California on the east, north, and south were overrun by thousands of miners from the Sierra Nevada gold-fields, and within a few years an extraordinary number of discoveries were made, some of which proved to be of great importance. The most powerful impulse to mining operations, and the immediate cause of a somewhat lengthy period of wild excitement and speculation was the discovery and successful opening of the Constock lode in 1859, in the western part of what is now the State of Nevada, but was then part of the Territory of Utah, and known as the "Washoe Country" (from a small tribe of Indians of that name). The locality of the lode, where there soon grew up a large town called Virginia City, is about 20 miles east of the boundary of California, and nearly due east of the northern end of Lake Tahoe. As early as August 1860 two mills were at work stamping and amalgamating the ore from the lode; mining had begun on a large scale; and many ingenious metallurgists were endeavoring to ascertain experimentally how the somewhat complex metalliferous combinations there occurring could be best and most economically treated. So far as quantity of bullion produced is concerned, these operations were eminently successful. The various estimates of the total yield of the lode from the time of its discovery to 30th June 1880, collected and published by Mr Eliot Lord, run from $304,752,171.54 to $306,181,251.05. The total production to the end of 1886 may be estimated as having been not far from $320,000,000. The bullion obtained from the milling of the ores contains about an equal amount in value of silver and gold. The mines on this lode thus added to the bullion stock of the world $100,000,000 more in eighteen years than the whole Freiberg district in Saxony had furnished in a little over 700 years (1168-1875). The lode is an ore channel of great dimension, included within volcanic rocks of tertiary age, which themselves have broken through pre-existing strata of Triassic age. It exhibits some of the features of a fissure vein, combined with those of a contact deposit in part and of a segregated vein in part. The gangue is quartz, very irregularly distributed in bodies often of great size, and for the most part nearly or quite barren of ore. The metalliferous portions of the lode, "bonanzas," as they are here generally called, are usually of great size, but extremely irregular in their position. Their number has been about twenty, most of them lying near the surface; but the last important one discovered was struck at a little over 1000 feet below the surface. Its dimensions were according to Mr Church about 700 feet in length, by 500 deep, and 90 wide; the average yield $93.55 per ton; and the total value of the bullion obtained from it $104,007,653. The mines on this lode have been worked to a greater depth than any mines in the world extending over an equal amount of ground. Up to October 1886 work was still being carried on at several points below the depth of 300 feet. The lower levels, below that of the Sutro tunnel, which intersects the lode at a point about 2000 feet below its outcrop, are now abandoned. Workings are still going on, however, above the great adit level, where there yet remain considerable bodies of low grade ore, which can perhaps be extracted with moderate profit, since more economical methods have been introduced both in mining and milling. The yield of the Comstock lode a present, although small as compared with that of its prosperous years, is still much larger than that of all the mines in the Freiberg district of Saxony.
The success of the Comstock lode workings led to the active exploration of the whole adjacent region, with the result that a great number of localities were discovered where auriferous and argentiferous ores occur, and some of these have been extensively wrought and have produced largely. In very few, however, do the ore deposits bear the distinguishing characters of true or fissure veins. Special mention may be made of the Meadow Valley and Raymond and Ely mines in Lincoln county. The first-named mine is in Pioche, 273 miles south of Palisade station on the Central pacific Railroad; the enclosing rock is quartzite of Lower Silurian age, the veins varying in width, but averaging from 2 to 2 _ feet, the ore being carbonate of lead near the surface with chloride of silver, passing into sulphurets, as usual, in going down. At the end of 1873 this mine was 1100 feet deep, and a large body of ore had been struck yielding $300 in value of silver per ton. The culminating years of the prosperity of these mines were 1872 and 1873, and the yield of the Ely district for those years respectively was $5,321,007 and $3,735,596. The Eureka district in the central part of Nevada is of importance on account of the magnitude of its yield, and because mining and smelting operations have been carried on uninterrupted since 1869, thus affording great facilities for scientific investigations. Its ores are chiefly galena, accompanied by the various oxidized combination resulting from its decomposition. Similar ores of zinc are also present, but in much smaller quantity. These ores are rich in gold and silver (average- 15 per cent. lead, 0.079 silver, and 0.00248 gold). The rocks in which they occur are chiefly limestones, and of Lower Silurian age; the deposits are very irregular in form. In many of their features they closely resemble the so-called pipe-veins of the North of England lead mines. Much of the ore has become decomposed, and has been subjected, since decomposition, to a rearrangement by water, analogous to stratification. The total yield of the Eureka district from 1869 to 1883 is stated at about $60,000,000 in value of gold and silver, and about 225,000 tons of lead. According to present indications, this district is approaching exhaustion.
Utah has important mines resembling to a considerable extent those at Eureka. The Hornsilver mine at Frisco, in southern Utah, is a large contact deposits, 30 to 50 feet wide, between dolomitic limestone and an eruptive rock called rhyolite or trachyte. The ores are sulphate of lead with some carbonate, associated with heavy spar, which occurs chiefly near the wall of eruptive rock. This mine has paid $84,000,000 in dividends, but none since 1884. The Little Cottonwood district, at a height of over 10,000 feet in the Wahsatch range, shows a record of about 3500 "locations" made within an area 2 _ miles square. It includes the famous Emma mine, where a large body of ore occurred occupying an eggshaped cavity in the Carboniferous limestone, which yielded largely (over $2,500,000); but it was soon worked out. The Flagstaff mine in the same canon, a "pipe-vein" or deposit occupying several irregular cave-like openings in the limestone, seems also to have been nearly or quite worked out. One of the largest and most productive miners in the country, and the most important one in Utah, is the Ontario, in the Uintah district, Summit county. The vein seems to be, in the lower levels at least, a contact mass between walls of quartzite and highly decomposed eruptive rock (called porphyry), and it varies in width from a few inches to 15 feet. It was discovered in 1872, has been worked by a company with $15,000,000 capital since4 1877, and up to February 1887 had paid $8,075,000 in dividends. The Silver Reef district in Washington county is a region of remarkable interest, where sandstones of Triassic age have been broken through and invaded by eruptive masses (andesites and trachytes), and where the ore, according to Prof. Reyer, occurs in flat masses and impregnation between the strata, adjacent to the eruptive rock, and is especially largely developed in contact with the remains of plants with which the rock is filled. The ores are carbonate of copper with chloride of silver, passing into the sulphuret at depths. According to the same authority, these mines produced a few years ago over a million of dollars a year; but they have much fallen off of late. The census report of 1880 gives the total product of the district up to 1st June 1880 at a little over $3,250,000.
The metalliferous deposits of Colorado are important from their magnitude and variety. Of the actual precious metal production, by far the largest portion is derived from pyrites and galena and their decomposition products. The telluride ores of Boulder county and the auriferous pyrites of Gilpin county, with a few individual deposits in the southern portion of the State, constitute the source from which it is derived. With these exceptions its mineral deposits may be considered as essentially silver-bearing. The principal source of silver is argentiferous galena and its decomposition products, while argentiferous grey copper or freibergite is, next to this, the most important silver-bearing mineral. The sulphides of silver also occur, and in some cases bismuth is found in sufficient quantity to constitute an ore. As yet, so far as known, no copper is extracted except as an adjunct in the reduction of silver-bearing copper ores. Placer deposits are generally confined to the valley bottoms among high mountain ridges; their present yield is relatively inconsiderable. Before the silver ores of Leadville were discovered, mining in Colorado was principally confined to approximately vertical veins in the Archean rocks of the Front range or in the eruptive rocks of the San Juan region; but since the limestone deposits of the Mosquito range have proved so exceptionally rich attention has been more and more turned to the ores in sedimentary rocks, and many new districts have been discovered, but none to rival that of Leadville. The Leadville ores are flat sheets, of the kind often designated in the Cordilleran mining regions as "blanket deposits" and appear to be contact deposits between the Carboniferous limestone and the overlying felsite, with additional or incidental ore accumulations in the limestone in irregular cavities. According to reports locally published the product of the Leadville "smelters" or smelting works in 1886 was-lead, 51,925,546 lb; silver, 4,569,013 oz., gold 22,504 oz.; total value, $7,515,148. From the mode of occurrence of the Leadville deposits it seems probable that they will within a few years become practically exhausted. The area over which the blue limestone of Emmons (dolomite of Rolker) has been found in places productive is, however, very large, having been estimated at 225,000,000 square feet. The Montana deposits, which up to 1880 are reported to have yielded fully $50,000,000, seem now to have been pretty much worked out. The workings from which the ores are now chiefly obtained appear to be of the class of segregated veins. The ores consist largely of auriferous pyrites in a gangue of quartz, oxidized in their upper portions and there easily manipulated, but in depth passing into the more refractory sulphurets. Unlike the ores described as occurring in Colorado and Utah, they are accompanied by copper rather than by lead, and they are also rather manganiferous than ferriferous. Much yet remains to be done before their nature and value can be fully understood; and the same may be said of the adjacent Territory of Idaho, the auriferous gravels of which resemble those of Montana, and have been next to those of California and Montana in importance (total yield to date estimated at $30,000,000). The deep gravels of Boise basin seem to be exceptional, and to resemble the deep or high gravels of California. A very large portion of the mines (other than placer) of Idaho appear to be of the fissure class, and to be enclosed in a country rock of granite, resembling in many respects the veins of the vicinity of Austin in Nevada. In Arizona, which ranks along with Idaho in the production of the precious metals, and is next to Michigan and Montana as a producer of copper, the mode of occurrence of the metalliferous deposits is complicated and varied, and is still very imperfectly known. They appear to be largely of the nature of contact deposits, dependent on the presence of some ancient or modern eruptive mass. The famous Tombstone district, in Pima county, has been a productive one, but seems at present to be declining.
The production of gold in the United States for each of the seven years 1880-86 inclusive is estimated (in millions of dollars) as 36, 34.7, 32.5 30, 30.8, 31.8, 35. Similarly the coining value of the silver produced during the same years is returned as 39.2, 43, 46.8 46.2, 48.8, 51.6, 51. The commercial value of silver has, however, of late been considerably less than the coining value 42, 42.5, and 39.4 in 1884-85-86.
Mercury. All the quicksilver produced in the United States comes from California, although small quantities of the ores of this metal have been obtained at various points in Colorado, and also in New Mexico. A little mercury has also been produced in Oregon. The California mines are all in the Coast ranges, in rocks of Cretaceous age. Small veins of quartz containing a little cinnabar have been found in the Sierra Nevada; but this ore is not known to exist anywhere in that range in workable quantity. The mercurial ores of the Coast ranges occur in very irregular deposits, in the form of strings and bunches, disseminated through a highly metamorphosed silicious rock. The first locality where this metal was successfully mined was New Almaden, about 100 miles south of San Francisco. Another locality New Idria- about 100 miles still farther south, has also been productive, but in a less degree. Mercury ores have also been mined at several points north of San Francisco, in the neighborhood of Clear Lake, where they occur, not only in metamorphic Cretaceous strata resembling those of New Almaden, but also in recent volcanic rocks, where gold has sometimes been found in intimate association with the cinnabar. The New Almaden mine has been productive since 1850, but the yield has varied greatly from year to year, partly on account of the irregularity of the mode of occurrence, and partly on account of interference on the part of the United States on a question of title to the property. The most productive year was 1876, when the number of flasks (of 76 _ lb) obtained was 47,194. The number produced in 1880 was 23,465, and in 1886 18,000. The total produce of the California mines was 59,926 flasks in 1880, 60,851 in 1881, 52,732 in 1882, 46,725 in 1883, 31,913 in 1884, 32,073 in 1885, and 29,981 in 1886. No new discoveries of localities of importance have been made during the past few years, and the mines now worked in California are all in a depressed condition.
Tin. Tin has been discovered innumerous localities, and various attempts have been made to open mines-in Maine, New Hamphire, Virginia, Alabama-but hitherto the amount of the metal produced has been quite insignificant. The region from which most has been expected is the Black Hills of Dakota, about 20 miles south-west of rapid City. The occurrence of the tin ore and the associated minerals at the mine to which the name of Etta has been given is very similar to that of the ores in the Erzgebirge. The cassiterite is disseminated through a granitic or granitoid rock in irregular bunches, strings, and even masses, associated with the usual minerals. There has not hitherto been any production of commercial importance from this source.
Copper. The present sources of copper are almost exclusively the Lake Superior region, and the Territories of Montana and Arizona. The mines of Lake Superior are the only important mines in the world in which the metal is exclusively obtained in the native state. The mode of occurrence of the copper varies, however, considerably indifferent portions of the mining district, which extends from Point Keweenaw along the southern shore of the lake to a little beyond the Ontonagon river. The most productive mines at present are those in the vicinity of Portgae Lake, about half-way between the eastern and western extremities of the cupriferous range. The rock in which the metal occurs is an old basalt, much metamorphosed from its original condition, and in the form now generally called melaphyre. This belt, commonly known in the region as the "trap range," is a volcanic material, interbedded in numerous alternating layers with sandstone and conglomerate, equivalent geologically to the Potsdam sandstones of the New York Survey or the Primordial of Barrande. The metal occurs along nearly the whole extent of Keweenaw Point in veins crossing the formation, and having all the characters of true fissure veins, the gangue being a mixture of quartz and calcite with various zeolitic minerals. Copper in large masses has been found in various mines on Lake Superior, but in none of such great dimensions as at the Minnesota mine, near the Ontonagon river. The largest mass discovered here weighed about 500 tons. Its length was 46 feet, its breadth 18 _, and its maximum thickness 8 _. While a considerable amount of copper has been obtained on Lake Superior in large masses, and lumps too small to be shipped separately, and therefore put in barrels and called "barrel-work," much the larger portion occurs in small grains, scales, and strings, disseminated through the rock. For crushing rock of this character a new form of stamp known as the Ball stamp was invented, one head of which is capable of crushing from 220 to 250 tons of rock in twenty-four hours. The most interesting mine on Lake Superior, and indeed the largest and most important not being an open work in the world, is that of the Calumet and Hecla Company. The mode of occurrence of the copper, which is all in the metallic form, and like that of the other Lake Superior mines almost chemically pure, is peculiar. The cupriferous mass is a bed of eruptive material, interstratified with other masses of similar origin, but itself a conglomerate made up chiefly of more or less rounded pebbles of eruptive rock rhyolite, trachyte, and basalt cemented together by native copper. The Calumet and Hecla mines, which form one connected work, have been opened over a length of about 1 _ miles, and to a depth, on the inclination of the metalliferous bed, which is about 390, of about 330 feet. The number of men employed is about 2800, and the production for 1886 was 22,552 tons (the total amount since 1866 being 201,529 tons).
The copper mines of Montana are chiefly in the vicinity of Butte City. The really important operations seem to be pretty closely limited to an area only 2 _ miles long by 1 mile wide, within which are three important silver mines, as well as the copper mines which make the district so famous. There are two great classes of mineral occurrences, - cupriferous veins, carrying more or less silver, and silver veins, with a manganese gangue, which carry little or no copper. These two groups have certain features in common. They all occur in granite, and are all accompanied by zones of decomposed country rock, which run parallel to and usually form the walls of all the large copper veins that have been opened to any great depths, and which are called porphyry dikes by the miners, but are really granite altered by the chemical changes which have accompanied the formation of the lode. They all pitch vertically or nearly so, and lack entirely the well-defined walls and the selvages which are characteristic of fissure veins. The cupriferous veins appear on the surface as wide bands of quartzose rock, much decomposed and stained with gossan. The surface ore always carries silver, is almost entirely in a free-milling condition, and generally in paying quantity. Nearly all the lodes at present worked for copper were at first worked for silver, and this condition continued until the water-line was reached, when the base ores-mainly the ordinary sulphuretted combinations of copper and of copper and iron, especially copper glance or vitreous copper and erubescite or variegated, peacock, and horseflesh ore-set in. the veins of great size, being often thirty feet wide for several hundred feet inlength. The average width of pay ore in the copper veins is stated to be not less than 7 feet; the Anaconda- the widest of any yet opened-average over 12 feet of profitable ore, and in many places widens to 30 or 40 for a great distance, showing no diminution in richness at the depth of 800 feet. In a part of these veins as, for instance, the Anaconda and Liquidation-the ore is copper glance in a gangue of quartz and decomposed feldspathic rock; while another type of veins, represented most perfectly by the Parrot vein, has nearly its entire metallic contents in the form of erubescite. This last-mentioned vein is also of great importance for its silver. The veins of the manganese-silver group lie all within a small area, but are of much interest and value. The gangue is quartz, heavily charged with its various oxidized combinations of manganese, all more or less argentiferous, the amount of silver ranging from the or four to several hundred ounces of that metal per ton. In these manganese veins the transition from decomposed oxidized combinations to the hard silicate and carbonate of that metal at the water-line is as sudden and striking as that from oxidized to sulphuretted ores in the previously mentioned class of veins. An exceptional occurrence in this district is that of the Gagnon mine, of which the gangue is chiefly quartz, and the ore argentiferous zinc blende.
There has of late years been a falling off in the production of copper in Arizona, but this appears to be due to unfavorable situation with reference to a market rather than to exhaustion. The Santa Rita mines, in New Mexico, near the Arizona line, were the first worked in that region, but are at present idle. The original workings were for metallic copper, occurring near the contact of a bed of limestone with an eruptive rock resembling felsite, the whole deposit being one of irregular character. Near the junction of the felsite and the limestone there is a series of parallel veins, in which the copper occurs in the form of carbonates and oxides. The Clifton district has been the scene of continuous mining operation since 1872, and is at present the largest producer of copper in the south-west. Its cupriferous deposits have been divided into three classes,-those occurring in limestone, those associated with porphyry, and those in the granite. The ores of the first class are the red oxide in a gangue of compact haematite and the carbonates in a gangue of brown manganese ore. The ores of the second and third class are oxides and oxysulphides, changing into copper glance at a trifling depth, and into yellow sulphurets in the deepest workings. The deposits are irregular, in some respects resembling contact deposits, and in others the metalliferous occurrences in the North of England lead mines. They are called by many mining geologists "pockets"; but other authorities consider them true veins. The most productive mine of the district the Longfellow - is described as being an almost vertical fissure in stratified limestone, at or near its junction with a dike of felsite.
Zinc. Zinc has become within the past few years an important article of production. The ores are found in very numerous localities, usually in connection with those of lead, both in the Appalachian range and throughout the comparatively undisturbed palaeozoic regions of the Mississippi valley. The Illinois zinc furnaces are at Peru, La sale, and Collinsville; those of Missouri mostly at Carondelet near St Louis, but there is one at Rich Hill and one at Joplin. Those of Kansas are at Pittsburgh, with the exception of oen at Weir City. There is also a small establishment at White River in Arkansas. There are also zinc works at Bergen Point, N.J., and at Bethlehem, Pa., and one small establishment in Tennessee.
== TABLE ==
Lead. The lead production was for many years, as already mentioned, limited to two districts near the Mississippi, - one, the so-called "Upper Mines," covering an area of 3000 to 4000 square miles included within the States of Wisconsin, Iowa, and Illinois; the other, the "Lower Mines," in south-eastern Missouri. The yield of the Upper Mines reached its culminating point about 1845; and in 1852 it had fallen off to about 15,000 tons. That of the Missouri mines also fell off, so far as the south-eastern district was concerned, but the loss was more than compensated by discoveries of ore in south-western Missouri, and latter in the adjacent State of Kansas. The production of all these districts (the lead of which contains but a trace of silver) for the years 1880-1884 is given by Mr E.A. Caswell as follows: - 24,700 tons in 1880, 27,470 in 1881, 25,900in 1882, 19,300 in 1883, and 17,567 in 1884. a considerable portion of the recently renewed activity the Missouri mines is due to the increased utilization of the zinc ores associated with the galena. The numerous lead mines opened and worked in various States in the Appalachian region, from Maine to North Carolina, have nearly all proved unsuccessful. Yet, on the whole, the country has largely increased its product a result due, chiefly, to the discovery and successful working of various lead ores containing silver in sufficient quantity to pay for separation, in several of the Cordilelran States and Territories. The total yield was 87,340 tons in 1880, 104,540 in 1881, 650 in 1882, 128,515 in 1883, 124,908 in 1884, 115,546 in 1885, distributed in 1883-84 as follows (Table XV.): -
== TABLE ==
To the non-metallic mineral substance mined or quarried in the United States, apart from coal and petroleum, which have been already considered, only very brief reference can here be made. The value of the lime and building-stone used in the country in 1885 was, for each of these articles, at least as great as that of the petroleum. Coal alone constitutes nearly seven-tenths of the value of the non-metallic minerals mined, and coal, petroleum, building-stone, and lime together make up almost nineteenth-twentieths of the same total. Other important articles are salt (value $4,825,345 in 1885), cement ($3,492,500), phosphate-rock ($2,846,064), and limestone for flux in iron manufacture ($1,694,656).
Salt. The utilization of the brine springs of New York and Virginia was begun towards the end of the last century, and has become extensively developed. To this development has been added that of similar saline resources in Ohio and Michigan. Previous to this, however, some salt had been made by the evaporation of sea-water at points along the coast, and especially in the neighborhood of Massachisetts Bay; and the census of 1880 showed still six establishments of this kind in existence, producing nearly 10,000 bushels of salt per annum. In California the evaporation of sea-water has attained some importance (884,443 bushels in 1880), the climatic conditions being much more favorable than along the northern Atlantic. A very small amount of salt was also made on the Florida coast. There are various lakes and partially or wholly dried-up beds of former lakes in the Cordilleran region, which are capable of furnishing a large quantity of salt, and some of these have been worked to a limited extent for use in metallurgy. By far the larger portion of the salt manufactured in the United States comes from the evaporation of brine, obtained by boring. The produce of the four brine-producing States (in bushels of 56 lb) is given as follows in the census report for 1880: - Michigan, 12,325,885; New York, 8,748,203; West Virginia, 3,105,333; Ohio, 2,650,301; total, 26,929,722; total production of all States, 29,800,298. The New York salt region is in the center of the State, near Syracuse. The brine is obtained in a detrital deposit, varying in size from the coarsest gravel to the finest sand, which fills depressions in the Onondaga or Salina shales, to the depth in places of 300 or 400 feet. These shales are of Upper Silurian age. No rock-salt has been struck by boring; but farther west, at various points in New York, Canada, and Michigan, the presence of large bodies of salt has been proved by the aid of the diamond drill. As yet, however, this source of supply has only been utilized to a limited extent. The salt of Michigan comes from several distinct geological horizons. The uppermost one is in the Coal-measures, the next lower in the Lower Carboniferous, and the lowest in the Onondaga or Salina salt group, the salt bearing formation of New York. It is only in the last-named formation that rock-salt has been found in Michigan , namely, at Bay City, on Saginaw Bay, where, at a depth of 2085 feet, a bed of salt 115 feet in thickness was bored through. In the Saginaw valley salt can be produced more cheaply than anywhere else in the country; the business of salt-making is associated with that o sawing lumber, and the refuse of the saw-mills feeds the fires under the salt-pans.
The following table (XVI.) shows the value of the metallic products of the United States for the years 1882, 1883, 1884, and 1885, as reported by the chief of the Division of Mining Statistics of the United States Geological Survey:-
== TABLE ==
The value of the iron is the spot value; that of the gold and silver the coining value; that of the copper, lead, and zinc the value at New York, and that of the mercury the value at San Francisco.
The total values of the mineral products of the United States for the same years are returned on the same authority as amounting respectively to $235,461,580, $249,049,889, $226,800,674, and $246,931,991. (J. D. W.)
1 The substance of the following paragraph is mainly derived from a paper read by Mr C. A. Ashburner, of the Pennsylvania Geological Survey, at a meeting of the American Institute of Mining Engineers in September 1885.
2 Paper read before the American Institute of Mining Engineers, Oct. 1886.
1 See Census Report for 1880 (1885).
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