306 



NATURE 



{Feb. 14, 1878 



A recent remarkable advance in the arrangements 

 necessary for utilising the transmitting power of the elec- 

 tric fluid over the metallic nerves of speech we propose 

 to bring briefly under notice. 



In every electrical circuit, so far, the limit of usefulness 

 has been restricted to the number of speaking stations or 

 instruments that could effectively be placed in circuit 

 upon the wire, and by the interference and confusion that 

 arises when more than one instrument is used at the same 

 time on such a circuit. To place upon an electrical circuit 

 more than eight or ten instruments has been practically 

 found impossible, the resistance of the instruments them- 

 selves being no small element of trouble, while the inter- 

 ference and interruption from multiple speaking has 

 hitherto been found an insuperable difficulty, and one 

 that has greatly tended to clip the wings and usefulness 

 of our modern Mercury. A system that will obviate this 

 trouble and enable any number of instruments to be 

 placed in connection upon the same circuit without the 

 possibility of interference or confusion, opens up a new 

 era in the usefulness of the telegraph as applied to social 

 purposes. It is such a system that will now be described, 

 a system that promises to revolutionise the systems that 

 at present spread over our chief manufacturing cities, and 

 guard the security of property. 



A simple illustration will explain the principles of this 

 auto-kinetic system. Let us suppose a tramway to be laid 

 down through the streets and suburbs of any of our large 

 manufacturing centres ; the two rails will thread the 

 thoroughfares in every direction, and at each junction, or 

 point of deviation down a bye street or other divergence, 

 a set of points are laid. There is practically no limit to 

 the number of these points that may be placed along the 

 line ; they may be one or one thousand. They remain 

 quiescent and of no value as far as the effective running 

 of the car upon the tramway is concerned until the car 

 passes over the special set of points that happen to be 

 required in the transit of the car from its starting-point to 

 its destination. The other nine hundred and ninety-nine 

 sets of points remain ready for use whenever the car has 

 occasion to pass over them, and their presence does not 

 in any way impair the usefulness of the tramway. The one 

 set of points brought into use has been effective in so far 

 that they have enabled the car to reach its destination, 

 and, having been used for a moment, they have again 

 reverted to their original position ; while the fact of their 

 being used has in no way affected the utility or efficiency 

 of the remaining points should any be required to pass a 

 car. 



Again, suppose two or three cars to be running over 

 various sections of the tramway at the same time, each 

 car could pass over its points on its journey without 

 detriment to the others, although all the cars might be 

 passing points upon the tramway at the same instant of 

 time ; the using of these two or three sets of points would 

 not inteifere with the remaining 990 odd sets of points 

 which at any moment might also individually be called 

 into requisition. Now the system of electric circuits to 

 be described may be likened to that of the tramway-line, 

 with its accessory junctions and points. A system of two 

 parallel wires is carried through a town. These wires in 

 pairs may be supposed for the purpose of the present 

 explanation to ramify continuously in every direction from 

 a central station up this street and down that, and to 

 embrace within their area the entire commercial and 

 social community. Like the points in the tramway 

 system, so upon the metallic circuit laid down, speaking 

 instruments may be placed at various points and stations 

 along the route, one or 1,000, because in the auto-kinetic 

 system under notice, no instrument is in circuit unless it 

 is, like the points on the tramway-line, being used. A 

 car going over the points makes those points for the time 

 being a portion of the tramway-line. So the circum- 

 stance of using the instrument upon the auto-kinetic system 



makes that instrument for the time being a portion of the 

 electric circuit, and the wires are alone occupied by this 

 transmission. 



Should any second or third instrument in other portions 

 of the circuit be brought into requisition at the same 

 interval of time, no interference can take place. As no 

 two cars could run over the same points on the tramway 

 at thie same moment, so no two instrumen's in the system 

 under notice can speak at the same time, but the second 

 or third instrument will automatically succeed the first in 

 the order in which they stand along the line from the 

 central station ; just as two or three cars would pass 

 the tram points in the order in which they had been 

 placed upon the line. 



The value of this new system of arranging metallic 

 circuits and the instrumental connections, whereby the 

 instrument is only a part of the electrical circuit so long 

 as it is speaking, being thrown off immediately upon the 

 cessation of the speaking current, cannot be estimated or 

 appreciated except by a special reference to its practical 

 development as regards the public and social telegraphy 

 of a large city. This will be fully demonstrated in a 

 subsequent paper by reference to the system of police, 

 fire, and social telegraphs proposed to be shortly carried 

 out for the Corporation of Glasgow, a system at once the 

 most comprehensive and complete that has as yet been 

 devised for affording multiple speaking stations upon the 

 same conducting wires without possibility of interference 

 or confusion. 



( To be continued.) 



OUR ASTRONOMICAL COLUMN 

 The Star Lalande 19,034. — It is somewhat singular 

 that this star, which was observed by Lalande, on March 21, 

 1797, and then rated 45m. should have been so little 

 observed since that year. It is not in Piazzi or Taylor, 

 but it was observed three times by Argelander in the 

 Bonn southern zones, viz., Z. 283, March 6, 1850, when it 

 is called 6m. ; in Z. 358, February 16, 1 851, where we find 

 it estimated 4m., and again in Z. 400, March 8, 1852, 

 where it is 5m. These circumstances taken together 

 appear to point to considerable variability. The star is 

 in an isolated position on the borders of the constellations 

 Hydra and Antlia. The mean of the Bonn observations 

 gives for its position i85o'o, R.A. gh. 34m. 26"4os., N.P.D. 

 112° 54' 4i"*o. Lalande's R.A. is one minute less than 

 Argelander's — yet it looks right in the histoire Celeste. 

 Perhaps one of our meridional observers may find oppor- 

 tunity to revise its position and the star may be further 

 recommended to attention on the score of probable fluc- 

 tuation of hght ; though it should be remarked that there 

 are other cases of discordant magnitudes in the Bonn 

 southern zones for stars not yet entered on the list of 

 variables, as in r] Canis Majoris for instance, for which in 

 three observations the magnitudes are 5, 3, and 2. 



Variable Nebula. — Prof. Winnecke in directing 

 attention to the nebula H. II. 278 as probably affording 

 the first indications of periodical va' lability of a nebula, 

 refers to the one discovered in Taurus on October 11, 

 1852, by Mr. Hind, as affording the single case where 

 astronomers generally have been agreed as to variation. 

 That nebula was detected on the morning of October 11, 

 in one of the most magnificent skies experienced in the 

 Regent's Park, being caught at once in slow sweeping, 

 with the low power-comet eye-piece of the 7-inch refractor. 

 Towards the end of the year 1876, in a fine sky with the 

 same telescope and eye-piece, not a vestige of it was 

 perceptible, and the same result attended several attempts 

 to discern the nebula in 1874 and 1875. Prof. Winnecke 

 mentions that it is not at present visible in our most 

 powerful telescopes. 



Minor Planets. — Observers who are still engaged in 

 the exploration of the region of the ecliptic have given 



