Part 7 (2/2)
Electric railroads--There was an instance of almost simultaneous invention in the case of the first practical electric railroads S D
Field, Dr Siemens, and Thomas A Edison all applied for patents in 1880 Of these, Field was first in filing, and arded patents The combined dynamo and motor were, of course, the parents of the practical idea Field's patents covered a motor in or under the car, operated by a current from a stationary source of electricity--of course a dynamo
These first electric roads had the current carried on the rail They were partially successful, but there was so was induction by the earth Later came, as a re a s wire overhead The question of how best to convey a current to the car- the attention of highly-trained intelligence everywhere The h power, and as such intractable; and it is in the character of this current, rather than in methods of insulation, that the remedy for the much-objected-to overhead wire is to be found It will be remembered that all the phenomena of induction are _unhindered by insulation_
Aside fro problem, the electric road is explainable in all its features upon the theory and practice of the dynamo and motor It is merely an application of the two eared to the truck-axle
A more modern mechanical improvement is to make the axle the shaft of the motor armature When the motor has used the current it passes by round By others there is a ”metallic circuit”--tires Many men whose interest and occupation leads them to a study of such matters know that the use of electricity, instead of steam locomotion, is merely a question of tie of electricity had not yet fully come It seems to us now that we have attained the end; that there is little ht in their day In the field of electricity there are yet to cos in the experiments of e seem tame and slow
Electrolysis--In all history, fire has been the universal practical solvent It has been supplanted by the electrical current in some of the most beautiful and useful phenomena of our time Electrolysis is the name of the process by which fluid chemicals are decomposed by the current
A familiar early experiment in electrolysis is the decoen, though always thought of and used as a sialvanic battery are ihtly mixed with sulphuric acid to favor electrical action, these poles will becoas which presently rise to the surface and pass off These bubbles are co froative pole Particles of the substance decomposed are transferred, some to one pole and some to the other; and, therefore, electrolysis is always practiced in a fluid in order that this transference may more readily occur
The quantity of _electrolyte_--the substance decoiven tith of the current When this electrolyte is composed of many substances a current will act a little on all of them, and the quantity in which the elementary bodies appear at the poles of the current depends upon the quantities of the compounds in the liquid, and on the relative ease hich they yield to the electrical action
The electrolytic processes are not the mere experiments a brief description of the the important processes for the mechanical products ofthat became a permanent fad in this country on the discovery of a special process so of modern tableware and table cutlery, as beautiful and much less expensive than silver, and the fine finish of the beautiful bronze hardware now used in house-furnishi+ng, are the results of the same process Some use for it enters into al or preserving of innumerable small articles that are made and used in unlieneral, but there arewhich interest only those engaged One of thean electrotype Thisof an exact i of a coating of the same on any metallic surface For were very co quality Even fresh, natural fruits that have been evenly coated with pluo may be covered with a thin shell ofstick, precisely confor on the outside to the form of the ithin
The deposit ofprocess always takes place at the negative pole--the pole by which the current passes out of the fluid into its conductor This is the ”_cathode_” The other is the ”_anode_” The ”bath,” as the fluid in which the process is accoold or platinum contains one hundred parts of water, ten of potassium cyanide, and one of the cyanide of whichever of those metals is to be deposited The articles to be plated are suspended in this bath and the battery-power, varying in intensity according to circumstances, is applied After re detail is practiced for different metals, and the current now co modern modifications of the dynamic current, is its use, raph and the telephone circuits of cities and the larger towns Every electric current may now be safely attributed to that source, and froenerator all in of electrolysis is said to be with Daniell, who noticed the deposit of copper while experi with the battery that bears his na, first published a description of the process in 1839 The Elkingtons were the first to actually put the process into co noere it apropos, to describe the seeilded, plated, were deceived and deceived others, previous to about 1845 For those things were done, and the genuineness of life has by no means been destroyed by the modern ease hich a precious metal may be deposited upon one utterly base A conteht lead at once to the conclusion that we could now spare one of the least in actual i and wonderful essence that alike ilds the plebeian pin that fastens a baby's napkin But fro electricity does
General facts--The naators of electrical phenomena are perpetuated in the fa its see subtlety, there is no force in use, or that has ever been used byso definitely calculated, measured, determined beforehand, as electricity is As time passes newproposed as lately as 1893 An instance of the value of some of these old determinations of a time when allof electrical science was unknown, iven in what is known as Ohen, in Bavaria, and was Professor of Physics at Munich, where he died in 1874 He forlish in 1847 He was recognized at the tiiven the Copley medal of the Royal Society of London The Law--for by that distinctive nah the name ”Ohm,” also expresses a unit of measurement--is that _the quantity of current that will pass through a conductor is proportional to the pressure and inversely proportional to the distance_ That is:
Current = Pressure / Resistance
Transposing the teret an expression for either of those elements, current, pressure, or resistance, in the terms of the other two This relation holds true and is accurate in every possible case and condition of practical work This remarkable precision and definiteness of action has made possible the creation of an extensive school of electrical testing, by which we are not only enabled to make accurate measurement of electrical apparatus and appliances, but also to ency of electricity When an ocean cable is injured or broken the precise location of the trouble isthe electrical resistance of the parts on each side of the injury_
The nitudes ofconvenient electrical units:
The VOLT (named from Volta) equals a unit of _pressure_ that is equal to one cell of a gravity battery
The OHM, as a unit of measurement, equals a unit of _resistance_ that is equivalent to the resistance of a hundred feet of copper wire the size of a pin
The AMPeRE (named from Ampere, 1775-1836, author of a ”Collection of Observations on Electro-Dynaator) equals a unit of _current_ equivalent to the current which one Volt of pressure will produce through one Ohm of wire (or resistance)
The Coulo electricity called the ”Torsion balance,” and general early investigator) equals a unit of _quantity_ of one A for one second
The Farad (from Faraday, the discoverer of the laws of Induction, see _ante_), equals that unit of _capacity_ which is the capacity for holding one Coulomb Death current--What is now spoken of as the ”Death Current” is one that will instantly overcome the ”resistance” of the human, or animal, body It is a current of from one to two thousand Volts--about the sahts
This question of the killing capacity of the current becae by the legislature of the State of New York of a statute requiring the death penalty to be inflicted by means of electricity The object was to deter evildoers by surrounding the penalty with scientific horror, [Footnote: Hence also the new lingual atrocity, the word ”electrocute,” derived from ”execute”
by decapitation and the addition of ”electro”] and the idea had its origin in the accidents which formerly occurred much more frequently than now The ”death current” is now alh the care of the rown to be much like that of men who continually handle firearms or explosives, and accidents seldoeneral public to appreciate the fact that the silent and har wires must be avoided There was suddenly a new and terrific power in common use, and it was as slender, silent and unobtrusive as it was fatal
Insulation of the hands by the use of rubber gloves, and extreme care, are the means by which those who are called ”linemen”--a new industry--protect themselves in their occupation But there is a new commandment added to the list of those to be memorized by the body-politic ”Do not tread upon, drive over, or touch _any_ wire”
It may be, and probably is, harmless But you cannot positively know [Footnote: It is a coeneral human nature to refuse to learn save by the hardest of experiences, and so far as the crediting of state that is not true, and reject ed witchcraft and diabolism, and of ”luck,” ”hoodoo,” ”fate,” etc, find ready disciples a of natural law When the railroads were first built across the plains the Indians repeatedly atte the ends of a rope stretched across the track in front of the engine, and with results which greatly surprised them When the lines were first constructed in northern Mexico the Mexican peasant could not be induced to refrain fro personal experiments with the neer, and scores of hi on the track was dangerous In the United States the era of accidents through indifference to co wires has ale because people are always governed by appearances connected with _previous_ notions, until _new_ experiences teach them better]
INSTRUMENTS OF MEASUREMENT--Some of the most costly and beautiful of modern scientific instruments are those used in the measurements and determinations of electrical science There are many forms and varieties for every specific purpose Electrical measurement has become a department of physical science by itself, and a technical, extensive and varied one Already the electrical specialist, no e physician is, has become professional He makes plans, submits facts, estimates cost, and states results with almost certainty
ELECTRICITY AS AN INDUSTRY--Immense factories are now devoted to the e establishments in cities are filled with the house is done in the sa is Soon thereof houses through a wire, and the kitchen being equipped with cooking utensils whose heat is for each vessel evolved in its own bottom, is inevitable