The normal polarization at the zenith, as dependent upon the position of the sun, was the foundation of Sir C. Wheatstone's polar clock.
Subsequently, in conjunction with Wheatstone, he introduced another form, in which five vertical index needles, each worked by a separate multiplier, were made to point out the letters on a dial.
Similar instruments to the single and double needle apparatus of Cooke and Wheatstone were about the same time invented by the Rev. H.
Another series of instruments, introduced by Cooke and Wheatstone in 1840, and generally known as " Wheatstone's step-by-step letter-showing " or " ABC instruments," were worked out with great ingenuity of detail by Wheatstone in Great Britain and by Breguet and others in France.
Wheatstone also described and to some extent worked out an interesting modification of his step-by-step instrument, the object of which was to produce a letter-printing telegraph.
At small country towns or villages, where the message traffic is light, the Wheatstone " A B C " instrument is used.
On long circuits wcrked by the Wheatstone fast-speed apparatus, and especially on those in which a submarine cable is included, it.
In the Wheatstone automatic apparatus three levers are placed side by side, each acting on a set of small punches and on mechanism for feeding the paper forward a step after each operation of the levers.
- Wheatstone Punching Apparatus.
In Squier and Crehore's " Synchronograph " system " sine waves of current, instead of sharp " makes and breaks," or sharp reversals, are employed for transmitting signals, the waves being produced by an alternating-current dynamo, and regulated by means of a perforated paper ribbon, as in the Wheatstone automatic system.
The messages in the form of perforated tape are then passed through an automatic transmitter, something like a Wheatstone transmitter, at a speed of about 100 words a minute.
As it uses the Baudot telegraph alphabet it has an advantage in theory over the Wheatstone using the Morse alphabet in regard to the speed that can be obtained on a long telegraph line in the ratio of eight to five, and this theoretical advantage is more or less realized in practice.
The slips are passed through an ordinary Wheatstone transmitter and actuate Wheatstone receiving apparatus which in turn controls a " Creed receiving perforator."
This machine reproduces a copy of the original transmitting slip, which can be passed on to any other Wheatstone circuit or can be run through a " Creed printer," which is a pneumatic machine actuating a typewriter by means of valves.
The heavier cores, with the consequent advance in speed of working attainable, have necessitated the introduction of automatic sending, the instruments adopted being in general a modification of the Wheatstone transmitter adapted to the form of cable signals, while the regularity of transmission thus secured has caused its introduction even on circuits where the speed cannot exceed that of the ordinary operator's hand signalling.
Owing to the difficulty of maintaining perfect balance on duplexed cables, curb sending is not now used, but the signals are transmitted by means of an apparatus similar to the Wheatstone automatic transmitter used on land lines and differing from the latter only in regard to the alphabet employed; the signals from the transmitter actuate a relay having heavy armatures which in turn transmit the signals to the cable; this arrangement gives very firm signals, a point of great importance for good working.
The earliest practical trial of electrical telegraphy was made in 1837 on the London and North Western Railway, and the first public line under the patent of Wheatstone and Cooke was laid from Paddington to Slough on the Great Western Railway in 1843.
This increase may be made evident by making the loop of wire one arm of a Wheatstone's bridge and so arranging the circuits that the oscillations pass through the fine wire.
In 1831 Wheatstone by his " magic lyre" experiment showed that, when the sounding-boards of two musical instruments are connected together by a rod of pine wood, a tune played on one will be faithfully reproduced by the other.
The line of circuit passed through the secondary of the induction coil I to the line, from that to the telephone T at the receiving station, 'See Journal of the Telegraph, New York, April 1877; Philadelphia Times, 9th July 1877; and Scientific American, August 181 This term was used by Wheatstone in 1827 for an acoustic apparatus intended to convert very feeble into audible sounds; see his Scientific Papers, p. 32.
Sir Charles Wheatstone discovered its principle and applied it as early as 1838 to the construction of a cumbrous but effective instrument, in which the binocular pictures were made to combine by means of mirrors.
Several pieces of apparatus have been invented for comparing the magnetic quality of a sample with that of a standard iron rod by a zero method, such as is employed in the comparison of electrical resistances by the Wheatstone bridge.
The primary coil carried the magnetizing current; the secondary, which was wound inside the other, could be connected either with a ballistic galvanometer for determining the induction, or with a Wheatstone's bridge for measuring the resistance, whence the temperature was calculated.
Depending on the fact that the electrical conductivity of a metallic conductor is decreased by heat, it consists of two strips of platinum, arranged to form the two arms of a Wheatstone bridge; one strip being exposed to a source of radiation from which the other is shielded, the heat causes a change in the resistance of one arm, the balance of the bridge is destroyed, and a deflection is marked on the galvanometer.
The two condensers to be compared are connected in the branches of a Wheatstone's Bridge and the other two arms R deter- completed with variable resistance boxes.
For the purpose of measuring resistances up to a few thousand ohms, the most convenient appliance is a Wheatstone's Bridge (q.v), but when the resistance of the conductor to be measured is several hundred thousand ohms, or if it is the resistance of a so-called insulator, such as the insulating covering of the copper wires employed for distributing electric current in houses and buildings for electric lighting, then the ohmmeter is more convenient.
The kaleidophone devised by Charles Wheatstone in 1827 gives these figures in a simple way.
SIR CHARLES WHEATSTONE (1802-1875), English physicist and the practical founder of modern telegraphy, was born at Gloucester in February 1802, his father being a music-seller in that city.
Wheatstone's education was carried on in several private schools, at which he appears to have displayed no remarkable attainments, being mainly characterized by a morbid shyness and sensitiveness that prevented him from making friends.
On the death of his uncle in 1823 Wheatstone and his brother succeeded to the business; but he never seems to have taken a very active part in it, and he virtually retired after six years, devoting himself to experimental research, at first chiefly with regard to sound.
Wheatstone's early training in making musical instruments now bore rich fruit in the continuous designing of new instruments and pieces of mechanism.
While in Paris perfecting a receiving instrument for submarine cables, Sir Charles Wheatstone caught cold, and died on the 19th of October 1875.
Wheatstone's physical investigations are described in more than thirty-six papers in various scientific journals, the more important being in the Philosophical Transactions, the Proceedings of the Royal Society, the Comptes rendus and the British Association Reports.
Cryptography had a great fascination for Wheatstone; he studied it deeply at one time, and deciphered many of the MSS.
But it is by his electrical work that Wheatstone is best remembered.
Wheatstone's Scientific Papers were collected and published by the Physical Society of London in 1879.
Wheatstone's Bridge >>
By the use of a revolving mirror similar to that used by Sir Charles Wheatstone for measuring the rapidity of electric currents, he was enabled in 1850 to demonstrate the greater velocity of light in air than in water, and to establish that the velocity of light in different media is inversely as the refractive indices of the media.
With Wheatstone's revolving mirror he in 1862 determined the absolute velocity of light to be 298,000 kilometres (about 185,000 m.) a second, or 10,000 kilom.
The principles of telegraphy (land, submarine and wireless) and of telephony are discussed in the articles Telegraph and Telephone, and various electrical instruments are treated in separate articles such as Amperemeter; Electrometer; Galvanometer; Voltmeter; Wheatstone'S Bridge; Potentiometer; Meter, Electric; Electrophorus; Leyden Jar; &C.
Cavendish also enunciated in 1776 all the laws of division of electric current between circuits in parallel, although they are generally supposed to have been first given by Sir C. Wheatstone.
in 1843, Sir Charles Wheatstone gave a great impulse to this study.
Christie (1784-1865) in 1833, and subsequently called the Wheatstone Bridge.
Cooke (1806-1879) and Sir C. Wheatstone in England, Joseph Henry and S.
1833), Siemens, Wheatstone, W.
In 1838 he communicated to the Academy the details of his apparatus, which utilized the revolving mirrors employed by Sir C. Wheatstone in 1835 for measuring the velocity of the electric discharge; but owing to the great care required in the carrying out of the project, and to the interruption to his labours caused by the revolution of 1848, it was the spring of 1850 before he was ready to put his idea to the test; and then his eyesight suddenly gave way.
WHEATSTONE'S BRIDGE, an electrical instrument which consists of six conductors, joining four points, of such a character that when an electromotive force is applied in one branch the absence of a current in another branch (called the conjugate branch) establishes a relation between the resistance of the four others by which we can determine the value of the resistance in one of these, that of the others being assumed to be known.
This arrangement was not invented by Sir Charles Wheatstone - although it bears his name and is commonly attributed to him, and was employed by him in some of his electrical researches - but by S.
This last resistance is connected to the other three with the addition 1 See Wheatstone's Scientific Papers, p. 129.
In one form of Wheatstone's Bridge, known as the series pattern plug-resistance bridge, or Post Office pattern, the two ratio arms, P and Q, each consist of a series of coils of wire, viz.
- Standard Wheatstone's Bridge.
Another form of Wheatstone's Bridge, shown in fig.
- Diagram showing Connexions of a Dial and Plug pattern, Wheatstone's Bridge.
The difficulty is " On a Modified Form of Wheatstone's Bridge, and Methods of Measuring Small Resistances," by Professor G.
For the measurement of low resistances a modification of the Wheatstone's bridge devised by Lord Kelvin is employed.
Modifications of the ordinary Wheatstone's bridge for very accurate measurements have been devised by H.
These and numerous modifications of the Wheatstone's bridge will be found described in J.
A lowresistance galvanometer is connected by a very fine wire (2 to 3 mils) to the centre C of the experimental wire AB, and also to the middle point D of the parallel wire so as to form a Wheatstone bridge.
48), essentially a Wheatstone pseudoscope, added just above the objective.
depressions appeared as elevations, and vice versa, or, as we must say after Charles Wheatstone, it presented a pseudoscopic impression; this quality, however, was not recognized by the microscopists of the time.
The instrument subsequently fell into complete neglect for nearly two centuries, to be revived in 1852 by Charles Wheatstone, who has stated that he had previously studied the problem; the publication of his views in his second great paper "On Binocular Vision," 1 in the Phil.
Riddell (1807-1867) devised his binocular microscope, which contained the essentials of Wheatstone's pseudoscope.
The Wheatstone instrument in the form devised by Stroh is still largely used in the British Postal Telegraph Department.
The most successful apparatus of this kind is that devised by Wheatstone; others were devised by Siemens and Halske, Gartner, Humaston, Siemens, and Little.
- Wheatstone Automatic Transmitter.
His ampere-balances, voltmeters and electrometers, and double bridge, are elsewhere described in detail (see Amperemeter; Electrometer, and Wheatstone'S Bridge).
Varley (1828-1883), Siemens and Wheatstone (see Dynamo).
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