the nozzle directed to throw the stream up the pipe. The discharge from the planted monitor nozzle causes a suction, and this draws the entire flow of water from the race, together with all boulders, tailings and débris, up the pipe, hurling the whole mass into a sluice built on the upper level, and supported by trestle. This upper sluice is provided with riffles, and catches the greater part of the fine gold. The lower sluice, or bedrock race, the flow of which is drawn up through the pipe, is also provided with riffles, and catches nearly all the nuggets and coarse gold.

The height of the elevator depends upon the force of the giant. If the monitor has a gravity head of only 200 or 250 feet, it will elevate but twenty-five feet; but if it has a head of 400 or 500 feet, it will elevate thirty or forty feet. Some elevators of this type are arranged with a second giant set midway of the inclined pipe, reinforcing the force of the one at the base, and the two easily elevate all tailings and by-water to a height of fortyfive or fifty feet. This elevation sets the upper sluice high above the bedrock, and affords dumping grounds of sufficient

capacity to meet all requirements for eight or ten years.

The force and power of an elevator of this type are remarkable. Boulders weighing 500 and 600 pounds are caught up by the monitor and hurled up the elevator as easily as a boy would toss up a marble. Anything that will go through the pipe is elevated, and as nothing larger than will pass through the pipe is allowed to roll or flow down the race, choking seldom occurs.

What diameter of pipe to employ depends of course upon the size of the monitor and the amount or strength of its gravity head, as well as upon the general water supply. A fifteen-inch pipe will elevate higher than a twenty-inch pipe, for the same reason that a threeinch nozzle will throw a stream a greater distance than a four-inch nozzle when subjected to the same pressure. For all general purposes the twenty-inch pipe is best, and is the size most generally used, as it is large enough to take care of the entire flow of the bedrock race, and will not choke as easily as pipes of smaller diameter, which experience shows are too prone to clog up, thus delaying the work.

OR some time past the United States Geological Survey has been making observations as to what is being done with a new group of steel hardening minerals. While these minerals have been known to the foremost metallurgists for some years, and while the minerals themselves are not new by any means, yet their application to steel manufacture is of very recent date and heretofore they have occupied more the position of curiosities than of commercial importance.

An English firm has been using steel hardening alloys for a good many years,

and recently the Bethlehem, Pennsylvania, manufacturers have been making many experiments along the same lines. The principal minerals used by the English company and by the Bethlehem people in their experiments are manganese, tungsten, vanadium and uranium, and others of the rare minerals. The effect of these minerals in steel manufacture is that one or two per cent of them will entirely change the nature of the metal, and it is to see how these qualities can be utilized most effectively that experiments are being made and observed by officials of the Geological Survey.

The attention of the Geological Survey

has been especially directed to operations in Texas, Utah and California, and it has been observed that where a few years ago the practical prospector seldom knew what a tungsten mineral was, now the exception is to find one who does not know. Improved methods of mining are being utilized and new and rich deposits are being uncovered.

Up to one year ago the world's output of vanadium was only about two hundred pounds per month and the process by which that was extracted from other minerals was very expensive, which resulted in giving to it a value many times the value of gold. Even considering the fabulous cost, its effects on steel produced profitable results; but, as seen, the total output was sufficient for working only a few tons of steel. Vanadium is now being used extensively in the manufacture. of the higher grades of automobiles, being utilized in conjunction with chromium for such work as axles, crank-shafts, driving-shafts, gears, connecting rods and springs. In spring-steels a large percentage of manganese is also used. It is contended that steel made with these alloys furnishes greater resistance to shocks, whether from sudden or minute vibrations, than any other metal, and imparts to steel dynamic properties not obtainable by any other method of metallurgy.

By reason of recent developments in America, and the opening up of large fields near Lima, Peru, vanadium has been put on a commercial basis, the price has sought its proper level, and it is now worth about half the price of silver.

Regarding the practical application of the steel hardening minerals to the iron and steel industry, it has been demonstrated that a small per cent, say of tungsten, will make a tool-steel that, al

though it is very hard to work up, will hold an edge after it gets a dull red heat. This enables lathes where tools of such steel are used to be speeded up so that their output is increased about three-fold. The practical machinist will appreciate what it means to work with a tool you cannot "burn" in the machine. A disadvantage of these excessively hard steels is that it is hard for the blacksmith to forge them. They are very refractory even at the highest forge heat, and there is hardly any way of sharpening them. but by grinding. No doubt this objection will be overcome at an early date.

The practical usefulness of manganese steel has already been demonstrated in dredger construction, where bearings and working parts made of it will stand three times as long under the cutting action of sand and gravel as ordinary. steel.

The mining regions of Texas are laden with rare earths, as shown from the Geological Survey's observations. In Llano county the Westinghouse company is mining yytrium and thorium for use in the construction of the Nerst lamps. They employ more than one thousand men in getting out those earths. Yytrium and thorium are good electrical conductors when hot, but non-conductors when cold. These earths, formed in pencil shape, take the place of the filament in the old style of lamp.

In the same region of Texas there were observed immense dikes with masses of pure feldspar thirty feet in diameter and running theoretically about seventeen per cent in potash. While this deposit has never been worked commercially, it is more than probable that an early date it will be utilized in the manufacture of potash fertilizer. Thus the world's supply of useful metals is ever increasing.

Y the application of the electric arc to the microscope, two European scientists have now opened the way for an intimate knowledge of the life and structure of bacteria, and improved methods of dealing with them will result.

After the invention of the microscope,

it was thought that no limits would be encountered in extending the scope of this valuable instrument, and that the realm, not only of the most minute organisms, but even of molecular and atomic structures, would be open to investigation, provided the magnification were increased sufficiently.

Now recent researches by Helmholtz and Abbe have shown that an insight into the structure of minute objects can be obtained by means of the microscope, only if the diameter of the former is upwards of one-four millionth of a millimeter. This limit is due to the phenomenon of deflection occurring with objects of smaller size, which prevents the production of any optical image; that is, objects of smaller size do not reflect a sufficient number of light rays to the eye to create an impression, especially after these have been made less intense by passing through the lenses of a microscope. Now the dimensions of certain bacteria are unfortunately as small as or smaller than this minimum diameter. H. Siedentopf and R. Zsigmondy, therefore, made a most valuable contribution to the advance of optics, when they designed a novel apparatus called the ultra microscope, which enables the limits of ordinary microscopes

FIG. 1.

The apparatus (Fig. 2) is mounted on a base plate (a) on which an optical bench (b) one meter in length is located. As a source of light there is used either a self-regulating projection arc lamp (c), which is so placed that the axis of the issuing beam. of light runs parallel to the optical bench, or the sun's rays themselves reflected by a heliostat in a horizontal direction.

to be far exceeded, making visible to the eye those particles which are out of reach of even the most powerful microscopes. The principle underlying the construction. of this instrument is as follows:

If a particle of smaller than microscopic size be struck by a beam of light, the ether vibrations will cause light rays to emanate from the particle in all directions independently of the shape of the latter. The particle thus behaves like a luminous body similar to the celestial bodies. This is confirmed by a most common every-day observation: if a brilliant beam of light be allowed to enter through a narrow slot into a darkened room, the beam will be seen to contain a multitude of dust particles whirling about, which under ordinary circum

A small projection objective (f) eighty

millimeters in focal length which corresponds with the forward lense of any projection lantern, such as the stereopticon, is fitted on the optical bench at about forty centimeters from its forward end. This objective is surrounded by a sheet metal screen intended to keep any side light away. Another part of the apparatus is the precision diaphragm (g), or screen, the size of whose opening can be accurately adjusted to one one-hundredth of a millimeter, and which must be moved back and forth on the optical bench until the projection objective produces a real image of the source of light on the slot of the diaphragm.

FIG. 4

This diaphragm, as represented in Figure 5, is intended for producing an adjustable illuminated volume in the liquid to be examined, and for adapting the depth of this volume to the power of the microscope objective used in each

case.

Another projection objective, fifty-five millimeters in focal length, is located at (h) Figure 2, at a distance of about fourteen centimeters from the diaphragm. This projects a real image of the diaphragm, and enables the observer to reduce the image of the opening of the slot without touching the latter.

At the extreme end of the optical bench

is mounted on a microscope support (i) by means of the plate (k), a cross slide (1). This cross slide can be moved by very small distances backward and forward either along the optical bench or across it, and allows the microscope to be accurately centered.

To the tube, a (Figure 1), of the microscope support there is fixed the objectivė, D, .4 millimeters in focal length and 75 millimeters in diameter. This objective, when fitted in a tube one hundred and sixty millimeters in length with a No. 4 Huygens eyepiece, magnifies the image of an object to three hundred and ninety times its size. To this objective there is fitted a curvette, which receives the liquid under examination. This, as represented in Figures 4 and 6, consists of a glass tube widened in the middle. Two windows of molten quartz are fitted in this widening, one of which is turned towards the eye and the other towards the source of light. The ends of the curvette are connected