440 CATTLE AS AN ECONOMIC FACTOR IN SOUTH AFRICA. 



racial animosities as between black and white in its one aspect, 

 and British and Dutch in its other aspect — animosities which still 

 profoundly affect the situation in our own day and generation, 

 even though the healing hand of time has done so much to 

 eliminate them — all these are strangely focussed in a single factor 

 from which there is no escape. 



And even with these important consequences before us our 

 study is not yet by any means completed, for the extraordinary 

 part played by cattle in the history of South Africa from the 

 time of the second British occupation onwards is yet to be told, 

 and in consequence this study is to be regarded as pre- 

 hminary to an examination of subsequent events. Moreover, a 

 right understanding of the whole position, and a true estimate 

 of the j)art played by this factor, requires investigation as to 

 the place of cattle in the native economy, and in the develop- 

 ment of trade as between black and white, in both of which 

 directions it is proposed to pursue the subject in the near future. 



Calcium Clouds in Stellar Space — The spec- 

 trographic observation of Nova Aquilae made by Dr. J. Lunt 

 and others have led to at least one remarkable deduction. It 

 is well known that the displacement to right or left of absorption 

 lines in stellar spectra indicate motion on the part of the star 

 under observation. In the case of Nova Aquilae, for instance, 

 several observers have been able to calculate its velocity in the 

 line of sight from the displacement of hydrogen lines in its 

 spectrum, and have estimated that velocity as being of the order 

 of 2.000 kilometres per second. Certain very narrow and sharp 

 lines of calcium in that spectrum, on the other hand, were 

 found to be virtually undisplaced, inaicating that the calcium 

 vapour causing those lines was virtually stationary. Mr. 

 Evershed has now drawn attention to similar observations made 

 in respect of Nova Persei in 1901, and Nova Geminorum (2) in 

 1912. He adds : 



If these novse, situated in widel\ different parts of the Milkj^ Way, 

 show calcium vapour stationary in the line of sight with respect to the 

 sidereal system, the probability seems great that the calcium has no con- 

 nection with the novs, but forms clouds of absorbing material distributed 

 over the Milky Way region, and that these are really at rest with refer- 

 ence to the system of stars, not merely at rest in the line of sight.* 



Mr. Evershed also gives a table for the velocities of six 

 binary stars which, he declares, adds cumulative evidence in sup- 

 port of the hypothesis of stationary calcium clouds. 



* Joury\. Brit. Astr. Assoc. 29, 87 (1919). 



