PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. 7 



3. " On the Beds between the Upper and Lower Chalk of Dover, 

 and their comparison with the Middle Chalk of Cambridgeshire." 

 By W. Hill, Esq., F.G.S. 



The following specimens were exhibited : — 



Rock-specimens and microscopic rock-sections, exhibited by 

 Wm. Hill, Esq., in illustration of his and Mr. Jukes-Browne's papers. 



Six specimens from the Streatham boring, from depths between 

 463 and 840 feet, exhibited by "W. Whitaker, Esq., B.A., E.G.S. 



Photographs of jSTew-Zealand Geysers, hot-springs, and sinter-ter- 

 races, taken by Josiah Martin, Esq., E.G.S., exhibited by Prof. J. W. 

 Judd, F.E.S., E.G.S. 



With regard to these photographs Prof. Judd spoke as follows : — 



Mr. Josiah Martin, E.G.S., has sent for exhibition a series of 

 photographs illustrating the geyser-eruptions and the sinter-ter- 

 races of New Zealand. These photographs have been obtained by 

 Mr. Martin during an expedition especially undertaken by him for 

 the purpose of studying the interesting phenomena of the volcanic 

 band in the North Island. 



By the application of the method of instantaneous photography, 

 Mr. Martin has been able to show that during the eruption of some 

 of the geysers a curious explosive action takes place, which has not 

 hitherto been observed. The body of heated water, after its rise 

 from the geyser-tube, is seen to be violently dispersed, probably by 

 a sudden liberation of high-pressure steam. Several of the photo- 

 graphs now exhibited illustrate this remarkable phenomenon in a 

 very striking manner. 



