524 Proceedmgs. 



swallow, he doubted very mucli whether, if brought here, it could be induced to remain 

 with us, the migratory instinct being very powerful. 



9. Dr. Hector exliibiled a telephone and two forms of the microphone, made by Mr. 

 John Kebbell, and explained the principles of their construction. The microphones were 

 placed on the lecture table, and connected by wire laid to different parts of the Museum 

 with several telephones in circuit ; the marvellous transmission of faint sounds was readily 

 illustrated. The experiments j^erformed were to some extent marred by the extreme sensi- 

 tiveness of the instruments, as the irregular noises produced by the rustling movements 

 of the audience frequently overpowered the sounds that were intended to be transmitted. 

 The sounds of the voice, of tuning forks, and slight friction of the sounding boards of the 

 microphones were, however, rendered distinctly audible throughout the complete circuit. 



A cordial vote of thanks was passed to Mr. Kebbell for his kindness in exhibiting to 

 the Society these interesting inventions. 



FouKTH Meeting. Slst August, 1878. 

 T. Kirk, F.L.S., President, in the chair. 

 New Members. — G. Morton, J. E. W. Cook, WiUiam Berry. 

 Additions to the library were laid on the table, and Dr. Hector drew attention to the 

 folloAving fishes lately added to the Museum collection, viz., Holocanthus arcuatus, Mono- 

 cantlms hi2:)pocrepis, and Serranus trutta (the latter being a new species) from Fiji, 

 collected and presented by Lord Hervey Phipps ; also, Ceratodus forsteri, from Queens- 

 land, presented by Sir C. Wyville Thompson. 



1. "On some of the Causes which operate in Shingle-bearing Eivers in 

 the Determination of their Courses and in the Formation of Plains," by 

 J. P. Maxwell,A.I.C.E. 



ABSTEACT. 



The author contended that the Canterbury Plains were formed by the 

 action of the rivers in conveying shingle from the ranges and depositing it 

 in their lower courses and at their mouths ; that continual changes in the 

 courses of the streams were effected by these deposits, thus giving rise to 

 the distribution of material over extended areas ; that this process was still 

 going on, and that the elevation and extension of the plains would pro- 

 ceed while the supply of detritus from the ranges continued ; that the features 

 were largely modified by the action of the sea in distributing the shingle 

 along the coast-line ; that examination of the river beds showed that they 

 are sometimes elevated along the middle lines of their length, and that 

 streams flowed on either side, cutting notch-like channels in the older plain 

 formation ; that the evidence of these channels on both sides of the river 

 beds is a suf&cient refutation of the theory of the supposed effect of the 

 influence of the earth's rotation in causing erosion on one side onl3^ 



Dr. Hector said he agreed with the views of the author as far as they went, but he 

 thought that the formation of the great fan-lilre deposits of shingle that go to make up 



