May 8, 1891.J 



SCIENCE. 



259 



may be read with the utmost accuracy. The tubes and scales are 

 protected from the weather by wooden hinged casings, which can 

 be opened at will. 



To obtain a given height or pressure at a given moment, the 

 cock of the corresponding glass tube must be opened, and the hy- 

 draulic pump set to work. When the mercury reaches the cock, 

 it rises at the same time in both the steel and the glass tube. By 

 working the hydraulic pump slowly, it can be brought exactly up 

 to the required level, but if the mark be overshot, a cerlain quan 

 tity of water under pressure is allowed to escape near the pump 

 at the bottom. This arrangement is carried out in tbe laboratory 

 at the foot of the tower. The necessary communication between 

 the two operators, one at the bottom and the other at any required 

 height, is effected by means of a telephone which the ascending 

 or descending operator carries with him, and through which he 

 can speak with those in the laboratory below. If the mercury 

 rises by mistake above the top of any one of the glass tubes it re- 

 turns to the foot of the tower through an o-verflow pipe. 



As the graduated scales behind each glass tube are not always 

 vertically superposed, their readings are harmonized by means of 

 two connected reservoirs of water joined by an India-rubber tube. 

 The horizontal plane for the base of each scale corresponding to 

 the upper level of the preceding scale can be ascertained from this 

 artificial level. 



A laboratory has been erected in the west pillar of the tower, 

 containing the hydraulic force pump, the mercury reservoir, the 

 telephonic station, and other accessories. Among these is a metal 

 gauge of large dimensions connected with the mercury under 

 pressure. It is marked to scale to show first the pressure in at- 

 mospheres, and second the numbers corresponding to the different 

 cocks up the tower. The operator is thus able to tell at once and 

 beforehand into which glass tube the mercury ought to rise under 

 a given pressui'e, and the right cock to get opened to show the 

 level it has reached. To calculate the pressure according to the 

 height to which the column of mercury is raised, the mean tem- 

 perature of the column in each experiment must be found. This 

 is done by measuring the variation in the electric resistance com- 

 municated by the column to the telephonic wire. 



The apparatus here described will be found of the greatest use 

 for making experiments on pressures hitherto impossible, and its 

 value from a scientific point of view can scarcely be overrated. 

 The thanks of all scientific men are due to M. Eiffel, who gener- 

 ously undertook tbe whole expense of constructing and setting up 

 the pressure-gauge, and also to M. Cailletet, to whose skilful de- 

 signs the success obtained is chiefly due. 



PRECIOUS AND ORNAMENTAL STONES AND DIAMOND 

 CUTTING.' 



Up to the present time there has been very little mining for 

 precious or semi- precious stones in the United States, and then 

 only at irregular periods. It has been carried on during the past 

 few years at Paris, Me. ; near Los CerrUlos, N. Mex. ; in Alexander 

 County, N.C., from 1881 until 1888, and on the Missouri River 

 near Helena, Mont., since the beginning of 1890. True beryls and 

 garnets have been frequently found as a by-product in the mining 

 of mica, especially in Virginia and North Carolina. Some gems, 

 such as the chlorastrolite, thomsonite, and agates of Lake Supe- 

 rior, are gathered on beaches, where they have fallen from rock 

 which has gradually distintegrated by weathering and wave 

 action. 



A very limited number of diamonds have been found in the 

 United States. They are met with in well-defined districts of 

 California, North Carolina, Georgia, and recently in Wisconsin, 

 but up to the present time the discoveries have been rare and 

 purely accidental. 



Of the corundum gems (sapphire, ruby, and other colored 

 varieties) no sapphires of fine blue color and no rubies of fine red 

 color have been found. The only locality which has been at all 

 prolific is the placer ground between Ruby and Eldorado bars, on 

 the Missouri River, sixteen miles east of Helena, Mont. Here 

 ' From Census Bulletin No. 49, by George F. Eunz. 



sapphires are found in glacial auriferous gravels while sluicing for 

 gold, and until now have been considered only a by-product. Up 

 to the present time they have never been systematically mined. 

 In 1889 one company took the option on four thousand acres of 

 the river banks, and several smaller companies have since been 

 formed with a view of mining for these gems alone or in connec- 

 tion with gold. The colors of the gems obtained, although beauti- 

 ful and interesting, are not the standard blue or red shades 

 generally demanded by the public. 



At Corundum hill, Macon County, N.C., about one hundred 

 gems have been found during the last twenty years, some of good 

 blue color and some of good red color, but none exceeding $100 in 

 value, and none within the past ten years. 



Of the beryl gems (emerald, aquamarine, and yellow beryl) the 

 emerald has been mined to some extent at Stony Point, in Alex- 

 ander County, N.C., and has also been obtained at two other 

 places in the county. Nearly every thing found has come from 

 the Emerald and Hiddenite mines, where during the past decade 

 emeralds have been mined and cut into gems to the value of 

 11,000, and also sold as mineralogical specimens to the value of 

 $3,000; lithia emerald, or hiddenite, to be cut into gems, ^S.^'iOO, 

 and for mineralogical specimens $1,500; rutile, cut and sold as 

 gems, $150, and as specimens, $50; and beryl, cut and sold as 

 iiems, $50. At an altitute of 14,000 feet, on Mount Antero, 

 Colorado, during the last three years, material has been found 

 which has aflforded $1,000 worth of cut beryls. At Stoneham, 

 Me., about $1,500 worth of fine aquamarine has been found, which 

 was cut into gems. At New Milford, Conn., a property was ex- 

 tensively worked from Oct., 1885, to May, 1886, for mica and beryl. 

 The beryls were yellow, green, blue, and white in color, the 

 former being sold under the name of "golden beryl." No work 

 has been done at the mine'since then. In 1886 and 1887 there 

 were about four thousand stones cut and sold for some $15,000, the 

 cutting of which cost about $3,000. 



Turquoise, which was worked by the Aztecs before the advent 

 of the Spaniards and since then by the Pueblo Indians, and largely 

 used by them for ornament and as an article of exchange, is now 

 systematically mined near Los Cerrillos, N. Mex. Its color i;i 

 blue, and its hardness is fully equal to that of the Persian, or 

 slightly greater, owing to impurities, but it lacks the softness of 

 color belonging to the Persian turquoise. From time immemorial 

 this material has been rudely mined by the Indians. Their 

 method is to pour cold water on the rocks after previously heating 

 them by fires built against them. This process generally deterio- 

 rates the color of the stone to some extent, tending to change it 

 to a green. The Indians barter turquoise with the Navajo, 

 Apache, Zuni, San Felipe, and other New Mexican tribes for their 

 baskets, blankets, silver ornaments, and ponies. 



The finest garnets and nearly all the peridots found in the 

 United States are obtained in the Navajo Nation, in the north- 

 western part of New Mexico and the north eastern part of Arizona, 

 where they are collected from ant-hills and scorpion nests by 

 Indians and by the soldiers stationed at adjacent forts. Generally 

 these gems are traded for stores to the Indians at Gallup, Fort 

 Defiance, Fort Wingate, etc., who in turn send them to large cities 

 in the east in parcels weighing from half an ounce to thirty or 

 forty pounds each. These garnets, which are locally known as- 

 Arizona and New Mexico rubies, are tbe finest in the world, 

 rivaling those from the Cape of Good Hope. Fine gems weighing 

 from two to three carats each and upward when cut are not un- 

 common. Tbe peridots found associated with garnets are generally 

 four or five times as large, and from their pitted and irregular ap- 

 pearance have been called "Job's tears." They can be cut into 

 gems weighing three or four carats each, but do not approach 

 those from the Levant either in size or color. 



Since the discovery of gold in California compact gold quartz 

 has been extensively used in the manufacture of jewelry, at one 

 time to the amount of $100,000 per annrmi. At present, however, 

 the demand has so much decreased that only from five to ten 

 thousand dollars' worth is annually used for this purpose. In ad- 

 dition to the minerals used for cabinet specimens, etc., there is a 

 great demand for making clocks, inkstands, and other objects. 



During the year 1887 about half a ton of rock crystal, in pieces 



