230 AVAILABLE SUXSHIXE. 



the slope of this line gives the angular elevation of the 

 "mean " sun — in this case 22°. The heig-ht of the siui at 

 any other hour — say midday — is obtained in the same way. 

 In schools all these results can he compared with the value.^ 

 observed by simple methods. 



5. For the true sun the following corrections may be 

 applied: — First, the values of the equation of lime can be 

 entered on a corner of the diagram or graphically, and the 

 position of the true sun can hence be shown by dots placed 

 on the first curve. The horizontal line for any day drawn 

 from the corresponding " true '' point will then give the sine 

 of the elevation of the true sun, its true local times of rising 

 and setting, the true amount of available sunshine, and so on. 

 Secondly, to get the corresponding times on a local clock, 

 we add or siibtract the equation of time and the difference 

 between local and standard South African time. 



6. It need hardly be added that all the diagrams can 

 be constructed completely with the help of a divided ruler, 

 pair of compasses and divided circle, without the use of tables. 



NOTE ON OLDER PALAEOLITHIC IMPLEMENTS 

 FROM THE TJMGITZA AND BEMBESI Y ALLEYS. 



By A. W. Macgeegor, B.A., F.G.S. 



With Plate XXX. 



Read Jvly 15, 1020. 



This note is intended mainly as a record of the localities 

 where older palaeolithic implements have been found to be 

 abundant, and a description of the types represented and the 

 conditions under which they were found. The types are 

 generally comparable with those of the European succession, 

 but as yet no verj- definite evidence has been adduced to prove 

 that they have the same chronological significance. 



The occuiTence of implements from the neighbourhood of 

 the Bembesi Valley has been known since W. H. Kenny, 

 a diamond prospector, brought a number of specimens into 

 the Rhodesian Museum some years ago. He would not state 

 exactly where he had found them, but the impression was 

 gathered that they came from the banks of the Bembesi River 

 itself. This is probably a mistake. In a stretch of 

 twelve miles of the river that I have mapped I have observed 

 no single specimen. Mr. Maufe, moreover, has elicited the 

 fact that many specimens Avere given to Mr. Kennj- by 



