xx President's Address 



stood by a number of persons at once, indeed, to be intelli- 

 gible all over a large chamber. Edison's speaking telephone 

 appears, from what has been written of it, to accomplish this 

 most satisfactorily. A combination of the microphone and 

 telephone forms a most delicate instrument for the deter- 

 mination of the tremors and vibrations of the earth which 

 occur in the neighbourhood of active volcanoes, and by its 

 aid Professor Palmieri has been able to detect tremors and 

 sounds otherwise insensible, which were found to precede 

 and accompany different phases of the recent eruption of 

 Vesuvius, and which afford certain warning of various stages 

 of volcanic action. A current from a galvanic battery 

 traverses a circuit in which is included the telephone and 

 the delicately balanced carbon contact pieces of Hughes's 

 microphone. The microphone is placed at the observatory, 

 nearest the active portion of the crater, and the slightest 

 tremor vibrates the two pieces of carbon in balanced contact, 

 and produces peculiar sounds in the telephone (at a safe 

 distance from the crater), which Professor Palmieri is able to 

 interpret. Another interesting application of these com- 

 bined instruments is Professor Hughes's indication balance, 

 which Mr. Joseph has already brought under notice of 

 this Society; and as he will exhibit it to-night, he will, I am 

 sure, explain its principles of -action to any one interested in 

 the matter. 



In my last address I called your attention to the labours 

 of our fellow-member and renowned botanist, Baron von 

 Mueller, and referred to the various botanical and allied 

 works which he had already published or which were in 

 progress. During the past year he has obtained additional 

 knowledge of the Australian flora by personal examination 

 of the Lachlan River district, as well as from an extensive 

 series of plants obtained by Mr. John Forrest during his 

 triangulation of the Nichol Bay district, and numerous con- 

 tributions from amateur collectors. The results are given in 

 the eleventh volume of the Fragmenta. A report on the 

 Forest Resources of Western Australia, from the pen of the 



