224 Intelligence and Miscellaneous Articles. 



have very different temperatures do not work well, I desired to 

 put the matter to the test by direct experiment. One of the in- 

 struments was left during several hours exposed to a temperature 

 of —18°, while the other passed the same time in an enclosure 

 heated to 40° C. The two instruments, put in communication, 

 transmitted speech perfectly. 



As soon as the telephone was employed on the telegraph-lines, 

 the action was remarked which is exerted upon the instrument bv 

 the currents used to work the Morse apparatus, and passing in 

 wires near that which connects the two telephones. This action 

 is attributable to an induction-phenomenon, to a deflection, or 

 perhaps to both causes combined. I have tried directlv at what 

 distance an intermittent current can produce an induced current 

 appreciable with the telephone. 



Two copper wires, perfectly insulated, were stretched parallel 

 over a length of 15*2 metres, and at distances varying between 15, 

 35, and 45 centimetres. One of the wires joined the pile and the 

 manipulator with the receiver of a Morse apparatus ; the earth-line 

 was formed by the gas-pipes. The two extremities of the other 

 wire communicated directly with the telephone. The current 

 employed produced a deflection of 60° on a telegraph-compass. 

 Tinder these conditions all the motions of the manipulator were 

 distinctlv perceived ; and I am persuaded that a telegraphist would 

 have understood the signs produced by the manipulator, even when 

 the distance between the two wires was 45 centimetres. 



It may hence be concluded, therefore, that on telegraph-lines 

 the noise heard in the telephone when a message traverses a neigh- 

 bouring wire may be attributed, at least in part, to induced currents. 

 This experiment may have a certain interest in the lecture-room, 

 to show at what distance an induced current can be produced. In 

 this respect the telephone is much more sensitive than the galva- 

 nometer.— Bib Uotheque Universe-Tie, Archives des Sciences Physiques 

 et Naturelles, No. 1, 1879, pp. 91-95. 



HARMONIC ORBITS. 

 To the Editors of the Philosophical Magazine and Journal. 



GENTLEMEN, 



M. Th. von Oppolzer's " Vulcan "-orbit (Oomptes Rendus, Jan. 6, 

 1879) represents another of my predicted harmonic orbits : — 



Distance, Time. 



Von Oppolzer -123 58-8 days. 



Chase, prediction .... -120 58-1 „ 



This leaves only one " missing link " in my triple series of prin- 

 cipal harmonics, extending from a Oentauri to the Sun. There are 

 many secondary harmonics, indicating possible asteroidal positions. 

 One of these has been confirmed by Mouehez's second Watson orbit. 



Faithfully yours, 

 Haverford College. Pennsylvania ' Pliny E. Chase. 



February 10, 1879." 



