scholarly journals Experimental researches in electro-magnetism

1837 ◽  
Vol 3 ◽  
pp. 181-184
Keyword(s):  
Acid Solution ◽  
Theoretical Investigation ◽  
The Other ◽  
Square Root ◽  
The Real ◽  
Conducting Wire ◽  
Series Of Experiments ◽  
The Common ◽  
The Wire ◽  
Experimental Researches

This communication consists of three parts. In the first part the author shows that the common deflecting galvanometer, in which the deflecting forces are assumed to be as the tangents of deflection, is founded on false principles, and consequently leads to erroneous re­sults. The wire forming the coil is of considerable thickness, and therefore there is no fixed zero from which the deflections can be reckoned. The length of the coil, also, being generally short, occasions another serious error, us the theoretical investigation is founded on the supposition of an indefinite length. In proof of the inaccuracy of the indications of the common deflecting galvanometer, the author took two elementary batteries, the plates of one being one inch square, and those of the other two inches. The tangents of the deflections of the needle (proper precautions having been taken for the equally free passage of all the electricity evolved in either case,) were very nearly as 1 to 2, though it is obvious that the real quantities of voltaic electricity were as 1 to 4. The author’s torsion galvanometer gave the degrees of torsion nearly as 1 to 4. Other experiments led to similar conclusions. The author then examines the laws which were supposed to connect the conducting power of a wire for electricity, with its length and diameter, and which, according to Professors Cumming and Barlow, varies directly as the diameter, and inversely as the square root of the length; but, according to MM. Becquerel and Pouillet, directly as the square of the diameter, and inversely as the length. He points out the false conclusions of M. Becquerel, and that he has, in fact, deduced the value of two unknown quantities from one equation j and that M. Pouillet having arrived at his through the fallacious indica­tions of the common deflecting galvanometer, they are equally erroneous. The author then hows that the law pointed out by Cumming and Barlow is, in ordinary cases, nearest the truth; though, under certain circumstances, the limits f even that law may be passed. Hence, and from a series of experiments with the torsion galvanome­ter, he arrives at the unexpected conclusion, hat there is no deter­minate law of conduction, either for the length or diameter of the wire, but that it must vary, in every case, with the size of he plates, and the energy of the acid solution used in exciting them. his con­clusion the author shows to be in accordance with the views of conduction which he had previously published; namely, that there is no actual transfer of electricity, but that all the phenomena result from the definite arrangement of the electric fluid essentially belonging to the conducting wire.

scholarly journals XV. Experimental researches in electro-magnetism and magneto-electricity

1833 ◽  
Vol 123 ◽  
pp. 313-321 ◽  
Keyword(s):  
Copper Wire ◽  
Careful Examination ◽  
Parallel Plates ◽  
Single Experiment ◽  
Constant Quantity ◽  
Conducting Wire ◽  
Series Of Experiments ◽  
The Wire ◽  
Four Square ◽  
Experimental Researches

According to the experiments of Professors Cumming and Barlow, the conducting power of a wire for voltaic electricity varies directly as its diameter, and inversely as the square root of its length. My own previous experiments on this subject, with all the conductors I then tried, led to the same result. According to the experiments of M. Becquerel, the conducting power varies directly as the square of the diameter or area of the section, and inversely as the length. M. Pouillet, from an extensive series of experiments, arrived at the conclusion that the conducting power was exactly proportional to the section of the wire, and inversely proportional to the length, increased by a constant quantity. Such discordant results, in establishing a fundamental law in electromagnetism, obviously require a more careful examination than has yet been bestowed on them. Before we admit the accuracy of the conclusions, we must first examine the accuracy of the galvanometer employed, and the different modes of using it. The mode employed by Professors Cumming, Barlow, and Pouillet, was to observe the deflections of a compass needle placed over the conducting wire, and calculate the forces by assuming that the tangents of deflection were proportional to the deflecting forces. Now, when the conductor is indefinitely long, the wire very fine, the needle placed very near it, and the arcs of deflection small, the results obtained will not be very far from the truth. These conditions approach to the assumptions from which the mathematical law is deduced. But when the wire placed below the needle is short, when the diameter is considerable, and when the arcs of deflection rise to sixty, seventy, or eighty degrees, the results calculated in this way will be found to deviate very far from the truth. When the wire is formed into a short rectangular coil, as in the common galvanometer, no numerical results can be obtained from its indications; for all the conditions assumed in the mathematical investigation are here completely violated. A single experiment will prove the truth of this assertion. Having placed four copper wires, about four inches long, parallel to one another, on a divided circle, I soldered the ends to those of four other wires about ten feet long, these wires being connected with an elementary battery, composed of two parallel plates of zinc and copper, each containing four square inches. The plates were immersed in diluted acid and the degree of deflection observed. An elementary battery, composed of two parallel plates, each one inch square, and having a single copper wire of the same diameter and length soldered to each, was connected with the ends of the four short wires, the battery immersed in the same acid, and the deflections observed. The tangents of these deflections, reckoning from the middle of the wires, were very nearly in the ratio of one to two, whereas the quantities of electricity were very nearly as one to four. When my torsion galvanometer (which is founded on no assumption,) was employed, the degrees of torsion were found to be nearly as one to four.

Who Got There First

2000 ◽  
Author(s):  
John H. Lienhard
Keyword(s):  
Acid Solution ◽  
Electrical Current ◽  
Smithsonian Institution ◽  
Liquid Pool ◽  
The Other ◽  
Electric Contact ◽  
Variable Resistance ◽  
Scientists And Engineers ◽  
The Subject ◽  
The Common

Years ago, a curator at the Smithsonian Institution said to me, “Scientists and engineers are nutty on the subject of priority.” That was before I realized just how far-reaching that nuttiness was or how misguided the very concept of priority is. As an example, try searching out the inventor of the telephone. Instead of Alexander Graham Bell, you may get the name of a German, Johann Philipp Reis. The common wisdom is that Reis invented a primitive telephone that was only marginally functional, while Bell’s phone really worked. Reis was a twenty-six-year-old science teacher when he began work on the telephone in 1860. His essential idea came from a paper by a French investigator named Bourseul. In 1854 Bourseul had explained how to transmit speech electrically. He wrote: . . . Speak against one diaphragm and let each vibration “make or break” the electric contact. The electric pulsations thereby produced will set the other diaphragm working, and [it then reproduces] the transmitted sound. . . . Only one part of Bourseul’s idea was shaky. To send sound, the first diaphragm should not make and break contact; instead it should vary the flow of electricity to the second diaphragm continuously. While Reis had used Bourseul’s term “make or break,” his diaphragm actually drove a thin rod to varying depth in an electric coil. Instead of making and breaking the current, he really did vary it continuously. Bell faced the same problem when he began work on his telephone a decade later. First, he used a diaphragm-driven needle that entered a water-acid solution to create a continuously variable resistance and a smoothly varying electrical current. Bell got the idea from another American, inventor Elisha Gray. Of course, a liquid pool comes with two problems. One is evaporation; the other is immobility. Bell soon gave it up in favor of a system closer to Reis’ electromagnet. Still, it is clear that Gray’s variable-resistance pool had pointed the way for Bell. Next we must ask whether Bell was influenced by Reis’ invention. Reis died two years before Bell received his patent. (He was only forty, and he never got around to seeking a patent of his own.)

The Bakerian lecture.— On the forms of equipotential curves and surfaces and on lines of flow

1876 ◽  
Vol 24 (164-170) ◽  
pp. 1-32
Keyword(s):  
Cross Section ◽  
Outer Boundary ◽  
The Other ◽  
Curves And Surfaces ◽  
Conducting Wire ◽  
The Wire ◽  
The Cross ◽  
Current Flows ◽  
The One

When any portion of a conducting-wire which joins the two poles of a voltaic battei'y is increased in size, the resistance of the circuit is diminished and a greater current flows through the wire ; and as any increase in the cross section of any portion of the wire causes a corre­sponding increase in the current, it is clear that there is no part of the conducting-wire through which some portion of the current does not flow from the one pole to the other; and the outer boundary of such a wire will be a line of flow. A line of flow is a line drawn in a conductor which indicates at every point of it the direction of the current at that point. A portion of the conductor completely enclosed by lines of flow may be termed a tube of flow.

The Fundamental Imaginary Dimension of the Real in Merleau-Ponty’s Philosophy

2015 ◽  
Vol 45 (1) ◽  
pp. 33-52 ◽  
Author(s):  
Annabelle Dufourcq
Keyword(s):  
The Other ◽  
The Real ◽  
Other Hand ◽  
Mental Entity ◽  
The Common ◽  
Ontological Model ◽  
Imaginary Field ◽  
Mode Of Being

The common opposition between the imaginary and the real prevents us from genuinely understanding either one. Indeed, the imaginary embodies a certain intuitive presence of the thing and not an empty signitive intention. Moreover it is able to compete with perception and even to offer an increased presence, a sur-real display, of the things, as shown by Merleau-Ponty’s analyses of art in Eye and Mind. As a result, we have to overcome the conception according to which the imaginary field is a mere figment of my imagination, a mental entity that I could still possess in the very absence of its object. On the other hand, the presence of reality is never complete or solid: “The transcendence of the far-off encroaches upon my present and brings a hint of unreality even into the experiences with which I believe myself to coincide.” Therefore, first, the imaginary (initially regarded as a peculiar field constituted by specific phenomena such as artworks, fantasies, pictures, dreams, and so forth) has to be redefined as a special hovering modality of the presence of the beings themselves. Second and furthermore: is not the imaginary always intertwined with perception? Merleau-Ponty advocates the puzzling thesis that there is an “imaginary texture of the real.” What is the meaning of this assertion? To what extent will it be able to blur the classical categories without arousing confusion? Can we avoid reducing reality to illusion? Lastly, consistently followed, this reflection leads as far as to discover, in the imaginary mode of being, an ontological model (the ontological model?), the canon enabling Merleau-Ponty to think Being, an “Oneiric Being.” Thus we will venture the apparently paradoxical contention that the imaginary is the fundamental dimension of the real. The notion of “fundament” becomes indeed problematic and receives an ironical connotation, however this is precisely what is at stake in a non-positivist ontology. Existence “lies” in a ghost-like, sketchy and unsubstantial (absence of) ground, in a restlessly creative being that is open to creative interpretations. And there it finds the principle of the ever-recurring crisis that both tears it apart and makes it rich in future promise.

The Other Hawthorne

2008 ◽  
Vol 81 (4) ◽  
pp. 559-595
Author(s):  
Robert Milder
Keyword(s):  
The Other ◽  
The Real ◽  
Common Notion ◽  
The Common

With their fluent colloquial prose and curiosity about life's spectacle, Hawthorne's voluminous notebooks belie the common notion that temperament and talent led him to write works of allegorical romance rather than realism. The essay argues that Hawthorne cultivated romance not because he believed in its idealizing vision but rather because, extrapolating from his experience of “the real,” he didn't.

scholarly journals On the compounds of tin and iodine

1851 ◽  
Vol 5 ◽  
pp. 565-566
Keyword(s):  
The Other ◽  
Detailed Account ◽  
The Real ◽  
Orange Colour ◽  
Series Of Experiments ◽  
Humphry Davy

Different properties have been assigned by different authors (as Sir Humphry Davy, Gay-Lussac, Boullay and Rammelsberg) to a combination of tin with iodine. With a view to explain these discordances, the author instituted the series of experiments detailed in this paper, and which have led him to the conclusion that the substance obtained by heating tin with twice its weight of iodine is a mixture of two salts, differing from each other in their composition. One of these is soluble in water to a slight extent without suffering decomposition, while the other is immediately decomposed on coming into contact with water; the former being the real proto-iodide described by Boullay, and the latter being a biniodide, a salt of which no particular description had hitherto been given, but which was probably the compound noticed by Sir Humphry Davy as being of a brilliant orange colour. The author found that this biniodide sublimes at a temperature of 356° F., while the proto-iodide, if protected from the contact of air, may be heated to redness without subliming. The author did not succeed in obtaining a combination of tin and iodine corresponding to the sesquioxide, although Boullay supposes that such was the composition of some yellow crystals which were formed by the mixture of solutions of proto-chloride of tin and of iodide of potassium. A more detailed account of the properties of the iodides of tin is reserved for a future communication.

Sampling the Web as Training Data for Text Classification

2012 ◽  
pp. 293-310
Author(s):  
Wei-Yen Day ◽  
Chun-Yi Chi ◽  
Ruey-Cheng Chen ◽  
Pu-Jen Cheng
Keyword(s):  
Data Acquisition ◽  
Text Classification ◽  
Document Classification ◽  
The Other ◽  
Training Data ◽  
Class A ◽  
Classifier Performance ◽  
Series Of Experiments ◽  
The Common ◽  
The Web

Data acquisition is a major concern in text classification. The excessive human efforts required by conventional methods to build up quality training collection might not always be available to research workers. In this paper, the authors look into possibilities to automatically collect training data by sampling the Web with a set of given class names. The basic idea is to populate appropriate keywords and submit them as queries to search engines for acquiring training data. The first of two methods presented in this paper is based on sampling the common concepts among classes and the other is based on sampling the discriminative concepts for each class. A series of experiments were carried out independently on two different datasets and results show that the proposed methods significantly improve classifier performance even without using manually labeled training data. The authors’ strategy for retrieving Web samples substantially helps in the conventional document classification in terms of accuracy and efficiency.

scholarly journals Experimental researches in electricity.—Fifth series

1837 ◽  
Vol 3 ◽  
pp. 211-211
Keyword(s):  
Electrical Current ◽  
The Other ◽  
Simultaneous Action ◽  
Electrical Machine ◽  
Chemical Decomposition ◽  
Effect Decomposition ◽  
Influence Of Water ◽  
The Common ◽  
Experimental Researches ◽  
Satisfactory Manner

The object of the author in this paper is to investigate the nature of electro-chemical decomposition. From the consideration of the circumstances of difference that mark the electricities obtained from the common electrical machine, and from the voltaic battery, and of which he had already established the theory in preceding papers, he was led to expect that the employment of the former in effecting chemical decomposition would exhibit some new conditions of that action, evolve new series of the internal arrangements and changes of the substance under decomposition, and perhaps give efficient powers over matter as yet undecomposed. For the purpose of greater distinctness, he divides the inquiry into three heads. In the first, he treats of some new conditions of electro-chemical decomposition, and shows that that effect does not depend upon the simultaneous action of two metallic plates, since a single pole might be used to effect decomposition; in which case one or other of the elements liberated passes to that pole, and the other element to the other extremity of the apparatus, the air itself acting as a pole. In the second, he considers the influence of water in electro-chemical decomposition; and he combats the opinion that the presence of that fluid is essential to the process is erroneous, and shows that water is merely one of a very numerous class of bodies, by means of which the electric influence is conducted and decomposition effected. In the third, he enters at large into the investigation of the theory of electro-chemical decomposition, and after discussing at some length the various theories of different writers on this curious subject, he is led to consider the effect in question as produced by an internal corpuscular action, exerted according to the direction of the electrical current, and as being the result of a force either superadded or giving direction to the ordinary chemical affinity of the bodies present; that is, modifying the affinities in the particles through which the current is passing, so that they act with greater force in one direction than in another, and consequently cause them to travel, by a series of successive decompositions and recompositions, in opposite directions, so as to be finally disengaged at the boundaries of the decomposing body. Various experiments are detailed in corroboration of these views, which appear to explain, in a satisfactory manner, all the prominent features of electro-chemical decomposition. decomposition.

scholarly journals Experimental researches in electricity. Ninth series

1837 ◽  
Vol 3 ◽  
pp. 318-319
Keyword(s):  
Electric Current ◽  
Single Pair ◽  
Fine Wire ◽  
Considerable Length ◽  
Good Conductor ◽  
Series Of Experiments ◽  
The Wire ◽  
The Moment ◽  
Experimental Researches ◽  
A Current

In the series of experiments which are detailed in this paper, the author inquires into the causes of some remarkable phænomena relating to the action of an electric current upon itself, under certain circumstances, whereby its intensity is highly exalted, and occasionally increased to ten, twenty, or even fifty times that which it originally possessed. For the production of this effect, the principal condition is that the current traverse a considerable length of a good conductor, such as a long wire; more especially if this wire be coiled in the form of a helix; and the effect is still farther augmented when this helix is coiled round a cylinder of soft iron, constituting an electro-magnet. The evidence on which these conclusions are founded is the following. If an electromotor, consisting of a single pair of zinc and copper plates, have these metals connected by a short wire dipping into cups of mercury, the electric spark consequent upon either forming or breaking the circuit is so slight as to be scarcely perceptible; but if a long wire be employed as the medium of connexion, a bright spark is obtained on breaking the contact. If the wire be coiled in a helix, the spark is still brighter; and if a core of soft iron be placed within the helix, the spark, at the moment of disjunction, is more brilliant than in any of the former cases: and the higher intensity of the current is also manifested by the occurrence of a shock, at the same moment, to a person who grasps with wetted hands the two ends of the wire; whereas no such effect, nor even any sensible impression on the tongue, is produced by the electromotor, when a short wire is employed. All these effects of exaltation are produced at a time when the actual current of electricity from the electromotor is greatly diminished; as the author shows by many experiments on the ignition of a fine wire, and the deflection of a galvanometer. He also proves that the effects of the spark and the shock, at the moment of disjunction of a long wire, are due to a current far more powerful than that which passes through the short wire at the same instant; or indeed than that which passes through either the long or the short wire at any other instant of time than when the disjunction takes place.

scholarly journals XXV. On a new series of periodical colours produced by the grooved surfaces of metallic and transparent bodies

1829 ◽  
Vol 119 ◽  
pp. 301-316 ◽  
Keyword(s):  
Royal Society ◽  
The Other ◽  
Metallic Surface ◽  
Intermediate Space ◽  
Original Surface ◽  
Series Of Experiments ◽  
The Subject ◽  
The Common ◽  
Academy Of Sciences ◽  
Distinguished Member

In the year 1822, when I received from Mr. Barton some very fine specimens of his Iris ornaments, I availed myself of the opportunity of performing a series of experiments on the action of grooved surfaces upon light. As the subject was to a certain extent new, many of the results which I obtained seemed to possess considerable interest, and I accordingly communicated to the Royal Society of Edinburgh a general account of them, which was read on the 3rd of February 1823. The interruptions, however, of professional pursuits prevented me, but at distant intervals, from pursuing the inquiry; and having found that M. Fraunhofer was actively engaged in the very same research, with all the advantages of the finest apparatus and materials, I abandoned the subject, though with some reluctance, to his superior powers and means of investigation. During a visit paid to Edinburgh by the Chevalier Yelin, a friend of Fraunhofer’s and a distinguished member of the Academy of Sciences of Munich, I showed him the general results which I had obtained; and as he assured me that the phenomena which had principally occupied my attention had entirely escaped the notice of his friend, I was thus induced to resume my labours, the results of which, in relation to one branch of the subject, I shall now submit to the consideration of the Society. When a flat and polished metallic surface is covered with equal and equidistant grooves, we may characterize it by the relation of two quantities, one of which m represents the breadth of each groove, or of the surface that is removed, while the other n represents the breadth of the intermediate space, or of the original surface that is left. If the image of a candle is seen by reflexion from such a surface, the trace of the plane of reflexion being parallel to the grooves, we observe the colourless image of a candle in the middle of a row of prismatic images arranged in a line perpendicular to the grooves. The colourless image of the candle is formed by the original portions n of the metallic surface, while the prismatic images are formed by the sides of the grooves m . This may be demonstrated ocularly by increasing m , and consequently diminishing n till the latter nearly disappears. In this case the intensity of the prismatic images rises to a maximum, while the ordinary colourless image becomes extremely faint, and vice versâ. The general phenomena of the prismatic images, such as their distance from the common image, and the dispersion of their colours, depend entirely on the magnitude of m + n , or the number of grooves and intervals that occupy any given space; and the laws of these phenomena have been accurately determined by M. Fraunhofer.

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