ANNIVEBSAET ADDRESS. 7 



a Journey in Brazil, by Louis Agassiz and his travelling com- 

 panions, Mr. Nicolay's reports are often quoted, and therefore his 

 accounts come before us with every claim to our reliance on their 

 accuracy and value. 



In resuming a discussion on the subject of the diamond, I am 

 desirous only of throwing as much light upon it as recent dis- 

 coveries and investigations afford, especially as, since 1870, the 

 further development of the diamond fields in Africa has created 

 fresh excitement, and made it desirable to afford explorers in 

 Australia the fullest information. 



Mr. Nicolay has ascertained certain facts which leave little 

 doubt that, however the diamond may have been formed, whether 

 according or not to any of the theories mentioned by me in 1870, 

 its matrix in Bahia is certainly a sandstone of Tertiary age.* 

 This too is Mr. Hartt's inference from Mr. Nicolay's researches. 



The sandstone it appears must once have overspread the whole 

 of the regions in question. It now forms the summits of flat- 

 topped ranges, which are designated by the word Chapada. In 

 1755 diamonds were discovered at Jacobina, in another portion of 

 the same sandstone on the strike of the diamond beds north-east 

 of St. Isabel do Paraguassu, as will be seen on the tracing which 

 I have had prepared from a sketch kindly lent to me by Mr. 

 Nicolay, on which has been shown the line of railway from 

 Cachoeira to Urubu. This tracing, together with Halfeld's and 

 Wagner's map of Miaas G-eraes (containing the geography of 

 that province up to 1862, the date of Tchudi's Memoir), will 

 show you the course of the Bio Francisco, the great river 

 bordering the mineral districts of the two provinces named. 



You will observe that the river Paraguassu rises in the central 

 part of a series of Serras, stretching from the Bio de Contas to 

 the neighbourhood of Pilao Arcado, on the Francisco, and runs 

 into the Bahia of Todos os Santos, on the Beconcavo or border of 

 which, at the sea junction, San Salvador, or the City of Bahia, is 



See Appendix (A.) 



