ABSTRACT OF PROCEEDINGS. XXV11. 



mantles were ruled surfaces, the paper shewed how the volumes of 

 series of longitudinally contiguous solids, with plane ends, and 

 skew or warped — ruled quadric — surfaces on the other sides, could 

 most conveniently be calculated. The determination of the 

 volumes of solids whose longitudinal axes were plane-curves, or 

 curves of double curvature, was also considered, and it was shewn 

 that the prismoidal formula was also rigorously applicable to 

 circularly warped solids, the centre of gravity in such changing its 

 position linearly with the distance along the curved longitudinal 

 axis. When the change of the centre of gravity of a right section 

 is a non-linear function of the distance along the curved axis, or 

 when the radius of curvature is not constant, the prismoidal 

 formula is not rigorously applicable. The paper closed with 

 suggestions as to the application of the formula?. 



EXHIBITS. 



(a) Twenty-four mounted photographs, including a series of 

 photographs of aboriginals representing two types, male and 

 female, a few illustrative of camp life and corroborrees, and a 

 special series illustrating some of the details of an Aboriginal 

 Bora Ceremony. The photographs were taken and exhibited 

 by Mr. Charles H. Kerry, and afterwards kindly presented to the 

 Society. Following is a note by Mr. Kerry: — 



"The photographs of an Aboriginal Bora Ceremony which I have 

 forwarded to the Royal Society form part of a series secured by 

 me in the Winter of 1898, locality Lower Macquarie River, N.S.W. 

 I was indebted to Mr. F. W. Hill, the owner of the adjoining 

 station " Quambone," for the privilege of being present on the 

 occasion. Many of the natives were in his employ, and all were 

 under heavy obligations to him for protection and kindness extend- 

 ing over many years. He was probably the only white man who 

 could have both gained entrance to the Bora ground and introduced 

 a friend. Enormous difficulties, however, had to be overcome to 

 break down the prejudice against allowing a white man to see this 

 secret ceremony, and even when successful in gaining admittance 



