158 Intelligence and Miscellaneous Articles. 



pebbles may be easily removed. The great conglomerates at the 

 base of the Cambrians, everywhere in Wales, indicate that there 

 were beach- and shallow-water conditions over those areas at the time, 

 and that the sea was then encroaching on an uneven land, becoming 

 gradually depressed to receive the subsequent Cambrian sediment. 



XXIII. Intelligence and Miscellaneous Articles. 



THREE EXPERIMENTS WITH TELEPHONES. 

 BY PROFESSOR E. SACHER. 

 TJN" order to ascertain what were the feeblest induced currents in 

 -*- the telephone that would be sufficient to produce in the ear di- 

 stinct sensations of sound, on December 27, 1877, I made the fol- 

 lowing experiments. 



1. I led the closed current-circuit of the telephone, at 20 metres 

 distance, parallel with the wire, well insulated with linen and wax, 

 of an ordinary telegraph-apparatus. The signals were given at first 

 by six, and afterwards by three Smee's elements (-^H 2 $0 4 ); and 

 they were, through the induced currents in the telephone, so dis- 

 tinctly audible that the message (by the two signals, long and 

 short) could be understood. 



2. I effected a division of the current by uncovering two places 

 in the insulated wire distant from each other 20 metres, and fixing 

 there the ends of a telephone-wire of equal strength and 120 metres 

 long. Reckoning, in addition, the thin wires in the interior of the 

 telephone, certainly only a small portion of the current went 

 through it ; and yet the rap was perceived with sufficient distinct- 

 ness for the message this time also to be understood. (Hence it is 

 easy to tap the messages of any open telegraph-line if one can learn 

 to read the Morse alphabet by hearing.) 



Experiment 1 succeeds also when the telegraph-wire is connected 

 with the thick, and the telephone-wire with the thin wire of a 

 Euhmkorff . If we wish to perceive the signals more distinctly, it 

 is advantageous to appropriate two telephones to the hearing ; it is 

 then, moreover, better to close the other ear against external noises. 



8. I connected the telephone-wire, about 40 metres long, with 

 the inner, thick wire of an ordinary induction-coil, and the wire, 

 120 metres in length, of a second telephone-system, with the outer 

 thin wire. To my great surprise, we could correspond both from 

 the first to the second telephone, and also (indeed apparently still 

 better) in the reverse direction, nearly as well as with the connexion 

 direct. The words were heard still more distinctly when I inserted 

 in the same manner two induction-coils. On the contrary, the ex- 

 periment was a failure when a Euhmkorff was employed in this 

 way ; the sound was too faint. — Kaiserliche AJcademie der Wissen- 

 schaften in Wien, matJi.-naturw. Classe, January 3, 1878. 



ON THE LIQUEFACTION OF HYDROGEN. BY RAOUL PICTET. 

 (IN A LETTER TO M. DUMAS.) 



Geneva, Jan. 11, 1878. 

 I have the satisfaction of communicating to you the result of an 

 experiment made on Thursday, January 10th, consisting in the 



