498 Mr. William CrooJces [June 11, 



minerals, iron oxide, shale, petroleum and diamonds are churned 

 together in a veritable witch's cauldron? As the heat abated the 

 water vapour would gradually give place to hot water, which, forced 

 through the magma, would change some of the mineral fragments 

 into the now existing forms. 



Each outbreak would form a dome-shaped hill, but the eroding 

 agency of water and ice would plane these eminences until all traces 

 ot the original pipes were lost. 



Actions such as I have described need not have taken place 

 simultaneously. As there must have been many molten masses of 

 iron with variable contents of carbon, different kinds of colouring 

 matter, solidifying with varying degrees of rapidity, and coming in 

 contact with water at intervals throughout long periods of geologi- 

 cal time — so must there have been many outbursts and upheavals, 

 giving rise to pipes containinn diamonds. And these diamonds, by 

 sparseness of distribution, crystalline character, difference of tint, 

 purity of colour, varying hardness, brittleness and state of tension, 

 would have impressed upon them, engraved by natural forces, the 

 story of their origin — a story which future generations of scientific 

 men may be able to interpret with greater precision than we can 

 to-day. 



Who knows but that at unknown depths in the earth's metallic 

 core beneath the present pipes there are still masses of iron not yet 

 disintegrated and oxidised by aqueous vapour — masses containing 

 diamonds, unbroken and in greater profusion than they exist in the 

 present blue ground, inasmuch as they are enclosed in the matrix 

 itself, undiluted by the numerous rock constituents which compose 

 the bulk of the blue ground ? 



If this be the case a careful magnetic survey of the country round 

 about Kimberley might prove of immense interest, scientific and 

 practical. Observations, at carefully selected stations, of the three 

 magnetic elements — the horizontal component of direction, the vertical 

 component of direction and the magnetic intensity — would soon show 

 whether any large masses of iron exist within a certain distance of the 

 surface. It has been calculated that a mass of iron 500 feet in 

 diameter could be detected were it ten miles below the surface. A 

 magnetic survey might also reveal other valuable diamantiferous 

 pipes, which owing to the absence of surface indications would 

 otherwise remain hidden. 



There is another diamond theory which appeals to the fancy. It 

 is said that the diamond is a direct gift from Heaven, conveyed to 

 earth in meteoric showers. The suggestion, I believe, was first 

 broached by A. Meydenbauer,* who says : — " The diamond can only 

 be of cosmic origin, having fallen as a meteorite at later periods of 

 the earth's formation. The available localities of the diamond 

 contain the residues of not very compact meteoric masses which may, 



* ' Chemical News,' vol. Ixi. p. 20f). 1 890. 



