very slightly, and which is preserved and guarded in Washington as sacredly as are the millions of Treasury gold— so has Congress enacted units or standards for the measurement of electricity; the standard units being: the volt, for pressure; the ampere, for current, or volume; the ohm, for resistance; and others for capacity, induction, etc.

The Weston Specialty.

The business of the Weston concern, then, is the manufacture of instruments for measuring electricity-instruments capable of indicating within extremely close limits the electrical quantities with which we have to deal in the laboratories and in all the various forms in which electricity is used to produce power, light or heat. In other words, we must be able to accurately measure any electrical force.

Important Branch of Electrical Art.

When the multiplicity of uses to which electricity is put to-day as a factor in the various arts is considered, the importance of this branch of electrical science will be realized. As an example, take the incandescent lamp industry and bear in mind that the energy required to bring any lamp to a standard candle-power must be known exactly and kept exceedingly uniform. If this is not done, and the necessary regular voltage is not given, the results are irregular light and a tremendous waste of the life of the lamp, for an increment of one volt will diminish the life far out of proportion to the ratio between one volt and the one hundred and ten volts, say, for which the lamp is designed. Not only, therefore, is a saving in lamps effected, but a large saving in coal bills, due to the fact that we have accurate means of telling how our dynamos are run, or knowing the volume of current or power being generated. As the dynamos are run by steam engines, the direct relation between fuel expense and electric power produced will be comprehended.

Pioneer in the Field.

The Weston Company has revolutionized this department of the electrical art. Its inception was due to the fact that sixteen years ago no meters were obtainable which could be depended on. The most extravagant tests were required for the most elementary measurements. Being engaged in the manufacture of dynamos, Mr. Weston had no reliable facilities for measuring the forces with which he dealt, so the old adage held true and "necessity became the mother of invention." Now his instruments are world standards. They are adaptable for the most delicate galvanometer measurements where the deflections of the instrument are obtained with a current of the strength of one five-billionth of an ampere, and are applicable, as well, for any range up to the highest capacity generated by Niagara or the power plant that drives a metropolitan system of railways. To appreciate the infinite delicacy of the firstnamed measurement, it may be said that a current of the strength of half an ampere illuminates the standard sixteen candle-power incandescent lamp; yet the galvanometer will distinctly indicate a change of power so incredibly small as to be beyond any possible human comprehension.

Tour of the Factory.

Shall we now take a walk through the works? A view of what may be seen in the various buildings will prove interesting.

Fire Proof.

Before we proceed, it may be remarked that the whole establishment is practically fireproof. Extinguishers are placed at convenient distances, and a fire plant with hydrants distributed throughout the factory is capable of throwing 1,000 gallons per minute. So convinced is the company of the efficacy of these precautions that no insurance is carried.

Dust and Dirt Proof.

Another important feature is that the buildings are designed to be as nearly dustproof and dirtproof as possible,

for the reason that with such delicate operations (probably the highest-class mechanical work done in the world) even dust may become an important factor in retarding the manufacture of the instruments and in interfering with their performance after completion.

Exacting Character of Operations.

By the following illustrations one will comprehend something of the extraordinarily difficult character of the work the Weston Company is obliged to do in its everyday routine: The minuteness of some of the parts used in certain instruments may be realized when it is known that 9,500 of a certain type of springs weigh only one ounce. Wire is “drawn” and constantly employed which has a diameter of from one-half to one-third that of the average human hair. Jewels are sized and ground. Nuts are made of dimensions so small that their shape, perfect hexagons, can scarcely be distinguished except by the strongest eye; these are drilled and threaded the same as any large nut, and for them are made screws to correspond. Certain parts of the instruments require a degree of accuracy to the limit of one fifty-thousandth of an inch, and work is frequently done which must be correct within one one-hundred-thousandth of an inch. Aluminum tubing, the smallest that can be made by any outside concern, is here so reduced in diameter that the human eye can barely perceive that it is hollow. This tubing, when utilized for galvanometer pointers, hands, or indicators, has a wall three-quarters of onethousandth of an inch thick.

Special Alloys.

For many electrical and mechanical purposes here required, no known metals were suitable; and it became necessary to discover special alloys containing several component metals of proportions exquisitely exact. In the Weston research laboratory a number of alloys have been discovered having electrical and mechanical properties hitherto entirely